1. bookVolume 58 (2021): Issue 2 (June 2021)
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Physiological, immunological and genetic factors in the resistance and susceptibility to gastrointestinal nematodes of sheep in the peripartum period: A review

Published Online: 08 Jun 2021
Page range: 134 - 151
Received: 09 Sep 2020
Accepted: 10 Feb 2021
Journal Details
License
Format
Journal
First Published
22 Apr 2006
Publication timeframe
4 times per year
Languages
English
Summary

Parasitic diseases of sheep involving gastrointestinal nematodes (GIN) are one of the main problems that affect fl ock productivity, especially during the peripartum period. Around lambing, the ewes are immunosuppressed and the nematode faecal egg count (FEC) increases at four weeks before lambing, reaching a peak between the fourth and sixth week postpartum and subsequently decreasing towards weaning. Prolactin has been credited with a suppressive effect on immune system, along with other hormones that intervene in metabolism, such as leptin, which has an important role in the activation of other hormones. Cortisol has also been included; this is stimulated by any stressful event and inhibits the proliferation of T-cells and alters the function of immunoglobulins. Another related hormone is pepsinogen, which is considered a marker of the integrity of the abomasum mucosa, as well as the albumin concentration that increases in the presence of a GIN infection. The humoral and cellular immune response, as well as inflammatory reactions, are the main mechanisms of action against GIN. Lymphocytes direct the effector mechanisms in a Th2 cell response, including interleukins (IL-4, IL-5, IL-9, IL-10) and transforming growth factor beta (TGF-β) together with immunoglobulins (IgA, IgG, IgM and IgE), which prevent the invasion of pathogens. Eosinophils with a cytotoxic effect are indicators of a parasitic infection, with importance in the immune protection of infected individuals. The genetic selection of resistant individuals measured by FEC is dependent on the heritability (h2), which is moderately inheritable and highly repeatable. Effects that influence the resistance or susceptibility of sheep to GIN infections in the peripartum period are determined by the interaction of various factors, such as genotype or breed, nutrition, age, type of birth, season and production system, etc., which are studied in this review.

Keywords

Introduction

Gastrointestinal nematode (GIN) infections are one of the main parasitic diseases that affect small ruminants around the world (Torres-Acosta & Hoste, 2008), causing physiological and productive alterations. Much work has been done in the search for control alternatives that minimise the consequences of parasitism that have an impact on the productive efficiency of fl ocks, particularly under grazing conditions (Mugambi et al., 2005; Vázquez-Hernández et al., 2006; Karrow et al., 2014) with emphasis on young lambs and ewes during the peripartum period (Kahn et al., 1999), when the problems of parasitism are accentuated by the increased faecal egg count (FEC) of ewes that are responsible for contributing to the contamination of the grazing area with GIN eggs (Beasley et al., 2010), in turn constituting a source of infection for suckling lambs (Ng´ang´a et al., 2004). In this period, immunosuppression occurs in sheep and goats, with interaction between physiological, immunological, nutritional and genetic factors, among others, which makes them susceptible to other infections.

From the immunological point of view, sheep with resistance to GIN are those that have the capacity to produce a greater number of cytokines derived from the Th2 response, related mainly to the reduced expulsion of eggs and the elimination of worms (Hayward, 2013). This being associated with high levels of IgE and eosinophils (Muñoz-Guzmán et al., 2006; Sayers et al., 2007; Lalramhluna et al., 2020), and high concentrations of IgA, IgG and IgM, with strong local immunity, effective in limiting the establishment and/or eliminating the worm population (Beasley et al., 2010; Albuquerque et al., 2019). This answer is very important and there are reviews of immunoglobulins associated with resistance in sheep to GIN (Aboshady et al., 2020). However, in goats appear to lack a functional IgA and eosinophil response against natural nematode infection (Basripuzi et al., 2018). Susceptible animals present a reduction in the counts of lymphocytes, leukocytes, mast cells and eosinophils in the abomasum mucosa, as well as a reduction in the concentration of IgG, IgE, IgM and IgA, facilitating the invasion of pathogens (O’Sullivan & Donald, 1973; Beasley et al., 2010; Albuquerque et al., 2019). On the other hand, the identification of genes for resistance to infectious diseases is based mainly on the search in DNA or in chromosomal regions for related loci; when these are identified, it would be possible to select resistant sheep within a population (Stear & Murray, 1994; Houdijk, 2008; Zvinorova et al., 2016). By developing resistant genotypes, associated with adequate feed consumption and balanced feeding, particularly in the peripartum period, an improvement in the immune response capacity of sheep will occur (Valderrábano et al., 2006; Kidane et al., 2010; Jones et al., 2012; Beasley et al., 2012; Werne et al., 2013), coupled with better development of the mammary gland and milk production during lactation. The purpose of this document is to review some physiological, immunological and genetic foundations, as well as certain factors that intervene in the expression and variability of resistance of sheep to GIN in the peripartum period.

Material and Methods

This review was carried out with the aid of the Elsevier platform (Scopus and ScienceDirect) and the Google Scholar, Redalyc, and Scielo Services. A total of 161 documents, like papers, theses, books, and meta-analyses, were consulted. The manuscripts were related to topics that revealed evidence about physiological, immunological and genetic factors related with the resistance and susceptibility to gastrointestinal nematodes of sheep in the peripartum period.

Ethical Approval and/or Informed Consent

This article does not contain any studies with human participants or animals by any of the authors.

Results and Discussion
Periparturient relaxation of immunity (PPRI)

The peripartum relaxation of immunity happens when the circulating eosinophils and plasma antibodies decrease and remain low at end of pregnancy and during lactation in ewes. At local level, lower titers of antibodies (IgG1, IgM, IgA and IgE) as well as few cell counts (globule leucocytes, mast and goblet cells) in intestinal tissue (Beasley et al., 2010).

There is a transitory increase in the excretion of eggs in the faeces, especially during the last third of pregnancy and the first weeks of lactation (Hamer et al., 2019). This phenomenon has been widely studied in small ruminants, particularly in sheep, and is known as postpartum rise, lactation rise or peripartum rise (PPR) (Houdijk, 2008; Torres-Acosta & Hoste, 2008; Kidane et al., 2010; Goldberg et al., 2012a; Fthenakis et al., 2015). In ewes, the number of eggs per gram (EPG) excreted in faeces increases from four weeks before lambing, reaching a peak between the fourth and sixth week postpartum (Courtney et al., 1985; Goldberg et al., 2012a), subsequently decreasing towards the time of weaning (Vázquez-Hernández et al., 2006). The rise in the egg excretion rate in faeces is associated with the increase in the fertility of the parasitic females as a result of a group of immunological factors being depressed in the peripartum period. This event may be accompanied by clinical signs due to the effect of gastrointestinal parasitism (Ng´ang´a et al., 2004; Werne et al., 2013). Increased susceptibility to other infections may also occur during this period (Ng´ang´a et al., 2004; Karrow et al., 2014), especially in ewes with high susceptibility to GIN due to high variability within breed (Gonçalves et al., 2018).

Physiological foundation of resistance in peripartum

In PPR, temporary alterations are characterised by physiological and metabolic changes associated to pregnancy and lactation (Ahmed et al., 2020). These changes also occur in cells and proteins of the immune system, that result in a low response of sheep against any infection, particularly those caused by GIN ( Gibbs & Barger, 1986; Barger, 1993; Kahn et al., 1999; Goldberg et al., 2012b; Jonsson et al., 2013; Pereira et al., 2020). The modulation of immune system is associated with disturbances in the endocrine system (Tembely et al., 1998; Beasley et al., 2010; Jonsson et al., 2013). Physiologically, it has been indicated that oestrogens stimulate the cellular and humoral immune responses by inducing direct effects on multiple cell types including immune and vascular cells (Trenti et al., 2018). In addition, in the peripartum period lactogenic hormones abound in the circulation and are antagonistic to oestrogens (Barger, 1993). Nutritional aspects (Jones et al., 2012), genetic influences (Kidane et al., 2010) and stress triggers also play important roles (Tembely et al., 1998). During the immediate prepartum period serum estrogens and estrone increase markedly. At partum withdrawal of progesterone the estrogens removes the block to lactation, and milk secretion results. Estrogen steroid decreased rapidly to low levels immediately postpartum and the release of growth hormone at parturition is required for normal lactation in ruminants (Convey, 1974) together with high levels of prolactin (Phillipps et al., 2020), as observed in Figure 1.

Fig. 1

Interaction of estrogenic and lactogenic hormones and nematode faecal egg count in the pregnancy and lactation of hair ewes. Elaborated with the information of several authors (Kann and Denamur, 1973; Convey, 1974; Ranilla et al., 1994; González-Garduño et al., 2014; Miura et al., 2019).

Prolactin

Prolactin is responsible for initiating and maintaining lactation, with a stimulating effect by the suckling lambs (Fthenakis et al., 2015). It has a suppressive effect on the host’s immune system, by reducing the IgA levels necessary to prevent parasitic establishment at the intestinal level (Torres-Acosta & Rodríguez-Vivas, 1995; Kahn et al., 1999; Houdijk, 2008), favouring growth of the nematodes and the fertility of the female worms. The increased levels of prolactin at lambing coincides with low number of circulating eosinophils and by decreased total antibody and IgG1 titers (Fthenakis et al., 2015). Progesterone, the principal steroidal regulator of pregnancy, also has several immunosuppressive activities. However, in ovariectomized sheep, prolactin alone had a greater effect on the reduction of FEC (Fleming & Conrad, 1989). Although prolactin together with progesterone reduces the number of cells such as eosinophils, but in pregnancy the FEC are not high, suggesting that other mechanism and hormones are involved (Torres-Acosta & Rodríguez-Vivas, 1995; Kahn et al., 1999; Houdijk, 2008; Beasley et al., 2010; Fthenakis et al., 2015). The results show that Haemonchus contortus larvae have possible receptors to progesterone and respond to progesterone by inhibiting their moulting and, in consequence, their development. These results suggest that progesterone participates in larval arrest (Gutiérrez-Amézquita et al., 2017). In pregnant Angora goats, a high EPG value is associated with a high concentration of prolactin, compared to non-pregnant goats, which maintain low levels of prolactin and EPG, with a correlation of 0.83 between these characteristics (Rahman & Collins, 1992). In dairy goats, the level of resistance/resilience is negatively correlated with the amount of milk produced (Hoste & Chartier, 1993; Chartier et al., 1998).

Leptin

During pregnancy, the placenta is the main provider of leptin. The levels increase at this stage and decrease gradually as the lambing date and lactation approaches (Ingvartsen & Boisclair, 2001; Mcfadin et al., 2002; Beasley et al., 2010). Ewes with high milk production and properly supplemented have a large amount of peri-renal fat, which in turn is related to a higher concentration of leptin in the blood and allows them to ensure fat tissue reserves and maintain good body condition (Rocha et al., 2011). On the other hand, leptin is an important regulator of the metabolic mechanisms of animals, and it has an important function in the immune system and in the activation of other hormones (Valderrábano et al., 2006). The function of leptin is linked to haematopoiesis and the induction of inflammation with activation of T lymphocytes, the production of Th1 cytokines and suppressing the production of Th2 cytokines (Ingvartsen & Boisclair, 2001). Beasley et al. (2010) found in infected Merino sheep approaching lambing that their leptin levels decreased and EPG increased. Ewes not supplemented or with reduced intake during pregnancy tend to lose body condition and energy reserves and presenting reduced leptin levels, which are related to loss of immune capacity against infections (Rocha et al., 2011).

Cortisol

Cortisol is a glucocorticoid that is released with any stressful event (Caroprese et al., 2010), as occurs just before lambing. Circulating cortisol stimulates the production of anti-inflammatory cytokines and inhibits the production of pro-inflammatory cytokines such as interferon gamma (IFN-γ), tumour necrosis factor (TNF-α) and interleukin-12 (IL-12); in addition, it inhibits the proliferation of T cells, modifies the action of Complement cells and alters the function of immunoglobulins (Aleri et al., 2016). All this leads to immunosuppression, increasing susceptibility to disease. At peripartum in ewes, the neutrophilia is commonly due to high cortisol levels at this time, which contributes to downregulation of surface adhesion molecules expression, in addition to an enhanced release of cells from the bone marrow (Ahmed et al., 2020). High cortisol levels in dairy cattle have been correlated with calcium and phosphorus deficiencies, causing hypocalcaemia problems in cows during the peripartum and provoking sensitivity to other infections (Kim et al., 2012).

Pepsinogen

Pepsinogen is a precursor to pepsin secreted by epithelial cells in the abomasum, the concentration of which generally increases at the time of expression of the immune response (Kidane et al., 2010), which coincides with the PPR from 4 weeks before lambing (Houdijk et al., 2000). An increase in pepsinogen concentrations is related to parasitism by Ostertagia spp. in abomasum (Simpson, 2000). As the parasite burden increases in the peripartum, the concentrations of pepsinogen and gastrin increase, the abomasum pH is altered, the abomasum permeability is increased and acid secretion is reduced (Houdijk et al., 2000; Davies et al., 2005; Angulo-Cubillán et al., 2007; Kidane et al., 2009), this being able to present diarrhoea (Miller & Horohov, 2006). In this sense, pepsinogen is considered as a marker of the integrity of the abomasum mucosa and a pathological indicator (Dominik, 2005; Kidane et al., 2009; Cei et al., 2016).

Albumin

Protein levels in the diet are responsible for the concentrations of blood components during an infectious process (Louvandini et al., 2006). From two weeks before lambing and during lactation, ewes supplemented with high-protein diets maintain high concentrations of albumin and urea (Houdijk et al., 2000; Kidane et al., 2010), which coincides with a reduced excretion of eggs in the faeces; conversely, decreases in the level of albumin and urea favour an increase in EPG (Zárate Frutos et al., 2014). A low albumin concentration is also considered a pathological indicator of the presence of an infection (Dominik, 2005).

Globulins

Globulins are altered during de PPR in sheep infected with GIN. Regardless of the protein content in the diet, globulin levels increase from four weeks before lambing (Houdijk et al., 2000; Zárate Frutos et al., 2014). The increase at final pregnancy stage is related to the presence of infectious or parasitic diseases (Zárate Frutos et al., 2014). Immunoglobulins constitute a natural defence mechanism in sheep, associated with inflammatory processes and the formation of antibodies. At the same time, increases in serum globulin levels are related to the quality of colostrum (Obidike et al., 2009).

Immunological mechanisms against parasitic infections

Once the host is infected by the nematode larvae, the epithelial cells are stimulated to generate an immune response, together with complement fixation and mucus secretions constitute the innate response to resist the primary infection (Hendawy, 2018), characterised by the action of some cytokines (Klion & Nutman, 2004). In addition, the small proteins and various cell types are stationary, such as interferons (IFNs) and virus-infected cells, or mobile, such as circulating leukocytes, monocytes, dendritic cells and lymphocytes. Leukocyte-derived cytokines are known as interleukins (ILs), and those originating from monocyte-macrophages are called monokines, both of which are produced as a protection mechanism for the host animal (Finkelman et al., 1997; Lippi et al., 2013; Karrow et al., 2014). Despite the fact that the immunological mechanisms are not very clear, the innate and acquired response capacity are those that have the greatest influence in the grade of infection (Muñoz-Guzmán et al., 2006). The acquired response dependent on previous exposure of the host to a foreign agent (González-Garduño et al., 2019) and characterised by specificity and antigen memory is the more important (Karrow et al., 2014). The immune response focuses on humoral and cellular responses (Gauly et al., 2002; Sayers & Sweeney, 2005), as well as in inflammatory reactions (Angulo-Cubillán et al., 2007). These immunological bases are considered important because parasites, mainly those hosted in the intestinal lumen, are capable of producing immuno-modulatory substances that escape the host’s immune response (Moreau & Chauvin, 2010).

Complement system recognition

The innate response is the first line of defence, capable of recognising molecular patterns associated with the pathogen in a shorter time, and occurs mainly through the Complement system (Fujita et al., 2004). A group of plasma proteins interact with bound antibodies and surface receptors that promote the elimination of pathogens (Castellano et al., 2004). By activating the classical and alternate pathways, high amounts of the enzyme C3 convertase are generated, depositing a large number of C3b molecules in the pathogen, attaching some molecules (opsonins) to its surface (Castellano et al., 2004; Fujita et al., 2004; Muñoz-Guzmán et al., 2006); through this opsonisation processes the elimination of pathogens occurs. In addition to this, the generated C3a and C5a peptides facilitate the mobilisation of eosinophils and neutrophils, favouring the inflammatory reaction; Complement activation regulates the cytotoxicity of eosinophils against larvae in the early stages of infection (Muñoz-Guzmán et al., 2006).

Cellular response

In the peripartum period, the immunological differences between lactating and dry ewes are notable, so that the immunological relaxation in the peripartum include the low cellular and humoral response affected by hormonal and nutritional aspects modified by season changes (Beasley et al., 2012). The elements involved in the immune resistance or susceptibility of sheep consider the following concepts. T lymphocytes are responsible for directing the effector mechanisms once they are stimulated by antigens. When activated, CD4+ T cells differentiate into two groups: helper T cells or lymphocytes, Th1 and Th2 (Muñoz-Guzmán et al., 2006; Sykes, 2010). Th1 cells are responsible for increasing the expression of interleukins IL-2, IL-3, IL-13, IL-25, IFN-γ and TNF-α (Finkelman et al., 1997; Miller & Horohov, 2006; Hayward, 2013), as well as an increase in mRNA expression for IL-6 as an indicator of gene expression, while Th2 cells include IL-4, IL-5, IL-9, IL-10 and TGF-β, with effector mechanisms in the cellular immune response (Finkelman et al., 1997; Maza-Lopez et al., 2020). The expression of these components induces a local inflammatory reaction in which different types of cells, such as basophils, eosinophils, neutrophils and lymphocytes are involved, together with specific antibodies, the gastrointestinal mucosa and inflammatory mediators (Meeusen et al., 2005; Ingham et al., 2008; Karrow et al., 2014); in addition, dendritic cells (DCs) and natural killer cells (NK) appear (Angulo-Cubillán et al., 2007). These immunological mechanisms facilitate a reduction in the number, size and fertility of worms (Rowe et al., 2008). Intracellular parasites generally involve the Th1-type response, whereas GIN such as H. contortus involve the Th2-type response (Miller & Horohov, 2006; Muñoz-Guzmán et al., 2006; Moreau & Chauvin, 2010), although there are situations in which Th1 and Th2 responses are involved for certain parasites (Murphy et al., 2013). Results found by Bricarello et al. (2008) in Nelore cattle indicated that the immune response to Cooperia punctata was probably mediated by Th2 cytokines (IL-4 and IL-13) in resistant animals, and by Th1 cytokines (IL-2, IL-12p35, IFN-γ and MCP-1) in the susceptible group.

Eosinophilia

As cellular components of immunity, eosinophils with a cytotoxic effect are one indicator of a parasitic infection. These cells have importance in the immune protection of infected animals (Hohenhaus et al., 1998; Davies et al., 2005). In the presence of GIN infections, effector immune responses characterised by the production of IgE and peripheral and tissue eosinophils associated with the production and activation of interleukins IL-4 and IL-5 are induced (Finkelman et al., 1997; Klion & Nutman, 2004). Once in circulation, eosinophils release the content of their toxic granules or metabolites onto the nematode cuticle, increasing cellular cytotoxicity, with release of proteins and mediators of inflammation (Klion & Nutman, 2004), favouring a lesion of the cuticle and the adherence of more eosinophils. In this way, regulation of the growth of GIN occurs together with the expulsion of eggs in the faeces of the host. Ewes in peripartum show a reduction in eosinophil count (Beasley et al., 2010; Pereira et al., 2020).

Humoral immune response

With GIN infection, the pro-inflammatory cytokines IL-4, IL-5, IL-9, IL-10 and IL-13 are involved in different mechanisms of the humoral response. One of these is through the IgA, IgG, IgM and IgE antibodies, which, being antigen receptors, prevent the invasion of pathogens through endocytosis of the antigen (O’Sullivan & Donald, 1973; Beasley et al., 2010); another is due to delayed maturation, reduced fertility and induction of parasite death. They are also involved in intestinal contractility, allowing the expulsion of worms (Miller & Horohov, 2006; Sayers et al., 2007; Houdijk, 2008; Hayward, 2013; Murphy et al., 2013; Wilkie et al., 2015). The surrounding IgA levels in the mucosa have been associated with reductions in the fertility and length of H. contortus, as well as a reduction in the parasite burden at the intestinal level (Amarante et al., 2005; Davies et al., 2005; Karrow et al., 2014; Hernández et al., 2016). Some studies have associated plasma IgA with FEC as an important immune response (Bowdridge et al., 2015; González-Garduño et al., 2018). High IgE levels are also involved in the expulsion of worms and in the regulation and activation of mast cells, eosinophils and basophils (Alba-Hurtado & Muñoz-Guzmán, 2013; Murphy et al., 2013; Karrow et al., 2014). The expulsion of worms due to the effect of IgE occurs through the release of vasomotor amines: compounds that stimulate the contraction of smooth muscle and increase vascular permeability, allowing fluid to escape into the intestinal lumen, resulting in displacement and expulsion of most of the nematodes implanted in the intestinal mucosa of the animal. IgG concentrations are associated with a reduction in excreted eggs in faeces (Murphy et al., 2013).

Genetic foundations of resistance

Resistance against GIN is polygenic in nature (Sayers & Sweeney, 2005; Zvinorova et al., 2016) and is quantitative; that is, it is influenced by a large set of genes or loci with small effects (Hayward, 2013; Karrow et al., 2014). The identification of genes related to resistance to GIN involves procedures based on molecular genetics, through the use of molecular markers, and the application of different strategies such as mapping of quantitative traits locus (QTL) regions by linkage disequilibrium, identification of candidate genes, the use of maps of high-density single nucleotide polymorphism (SNP) and complete genome (genome-wide) association studies (Keane et al., 2006; Bishop & Morris, 2007; Wilkie et al., 2015; Zvinorova et al., 2016), as well as microarray analysis, are very useful in determining post-infection gene expression. All these procedures offer advantages and opportunities to investigate resistance genetics and parasite–host interactions (Hayward, 2013).

Genetic selection criteria

The ability to express resistance between and within breeds is genetically regulated (Stear & Murray, 1994), which is why selection can be made either directly through identifying the genes or alleles involved by means of molecular genetic techniques or indirectly through phenotypic indicators such as worm counts, FEC (Beh & Maddox, 1996; Davies et al., 2005; Good et al., 2006), packed cell volume (PCV), antibody levels, specifically IgA and IgE (Karrow et al., 2014), eosinophil count, pepsinogen concentration (Beh & Maddox, 1996) or other variables related to the immune response. One of the main variables by which the parasite burden is determined has been the EPG count, and this is one of the main phenotypic selection criteria. It must be evaluated by measurements over time, establishing the dynamics of the curve in the peripartum period and the correlation with other productive characteristics (Goldberg et al., 2012b).

Genetic selection is dependent on the heritability (h2), which in the case of FEC is considered moderately inheritable and highly repeatable (Bishop & Morris, 2007; Saddiqi et al., 2010), similar to other productive characteristics. Values from 0.15 have been observed (Vanimisetti et al., 2004), but other authors indicate values of 0.25 to 0.30 (Sréter et al., 1994; Kahn et al., 1999) and even up to 0.63 (Miller & Horohov, 2006; Alba-Hurtado & Muñoz-Guzmán, 2013). Selective breeding of the maternal line for nematode resistance has potential epidemiological benefits by reducing pasture infectivity (Vineer et al., 2019).

Identification of genes related to resistance

The genetic basis of resistance is closely related to the immunological component, most of the loci involved with immunological processes are located in the Main Histocompatibility Complex (MHC), a highly polymorphic region that consists of a group of closely linked genes involved in the presentation of antigens in the host’s immune system. Association of the FEC with the MHC I and MHC II regions adjacent to chromosome 20 of sheep has been found (Stear & Murray, 1994; Karrow et al., 2014) with the amount of FEC (Keane et al., 2006; Karrow et al., 2014; Zvinorova et al., 2016). The DRB1 locus of MHC II has been associated with resistance to GIN, particularly with increases in IgA and IgE levels (Dominik, 2005; Hassan et al., 2011; Hayward, 2013; Karrow et al., 2014). Also, with IFN-γ gene located on chromosome 3, a strong association between one allele of this gene has been detected with the reduction in FEC and an increase in the levels of specific antibodies (IgA) against Ostertagia circumcincta in lambs (Karrow et al., 2014). However, some authors have cited that expression of the IFN-γ gene does not directly influence resistance to GIN (Dervishi et al., 2011; Alba-Hurtado & Muñoz-Guzmán, 2013; Karrow et al., 2014). Likewise, with the IgE gene (Díaz et al., 2005; Pettit et al., 2005; Keane et al., 2006; Sayers et al., 2007; Karrow et al., 2014) a strong Th2 cell response has been detected during infections, with overexpression of IL-13, IL-5 and TNF-α (Alba-Hurtado & Muñoz-Guzmán, 2013). The OMHC1-188 and OLADRB2-282 alleles of the MHC influence the differentiation between genotypes in the antigen-presenting mechanisms (Alba-Hurtado & Muñoz-Guzmán, 2013). Of the TLR variants, the TLR4 gene is reported to be involved with the immune response to parasitic infections, as are other nearby genes, TNFSF8 and TNFSF15, which encode cytokines belonging to TNF-α (Lin et al., 2016).

After evaluating the ALOX15, CD109, CD163, CPA3, EMR3, IL-13, KIT and MAP3K5 genes, it was found that ALOX15 and IL-13 play important roles in resistance to GIN (Wilkie et al., 2015) and were significantly increased in resistant animals and expression was negatively correlated with FEC. The expression of different genes at the intestinal level has been evaluated in two divergent lines by means of microarray analysis, with the highest expression in susceptible animals of HLA-A, MSH6, GPX2, IF135, UBD, SERPING1 and TFF3, the expression being generally associated with the stress caused by parasitic infection, such as in the case of GPX25; in contrast, resistant animals showed higher expression of the RAC2, ITGB2, DAP3 and TRADD genes associated with neutrophilia and post-infection cellular processes and of importance in innate immunity (Keane et al., 2006). As indicators of the genetic influence on resistance, the presence of QTL regions for EPG on chromosomes 1, 2, 3, 6, 14, 19 and 20 has been revealed for different nematodes, including H. contortus, and on chromosome 1 for haematocrit (Bishop & Morris, 2007). Other authors have reported different QTL regions in sheep for H. contortus, such is the case of chromosomes 1, 3, 6, 8, 14, 20 and 22 (Miller & Horohov, 2006; Zvinorova et al., 2016).

Factors influencing resistance and susceptibility

The physiological, immunological and genetic effects that influence the resistance or susceptibility of ewes to GIN infections in the peripartum period are determined by the interaction of various factors:

Genotype or breed

The resistance of some genotypes depends largely on conditions of environmental origin (Alba-Hurtado & Muñoz-Guzmán, 2013) and flock management. Generally, native genotypes such as Red Maasai (Wanyangu et al., 1997), Santa Inés (Rocha et al., 2004; Albuquerque et al., 2019), Crioula Lanada (Bricarello et al., 2004), Barbados Blackbelly (Yazwinski et al., 1981; Zaragoza-Vera et al., 2019), Florida Native (Courtney et al., 1984, 1986; Díaz-Rivera et al., 2000), Castellana (Gómez-Muñoz et al., 1999), Pelibuey (Morteo-Gómez et al., 2004; Palomo-Couoh et al., 2017), and Mexican creole (Alba-Hurtado et al., 2010) are more resistant to H. contortus. Native genotypes, which for many years have thrived in unfavourable environments with poor zootechnical management and without exposure to anthelmintic treatments have proven to be more resistant (Alba-Hurtado & Muñoz-Guzmán, 2013). The use of genetically resistant animals can optimise the use of anthelmintics and delay the resistance capacity of nematodes against anthelmintics (Bricarello et al., 2004). In the same way, the selection of sheep resistant to GIN in the peripartum period would favour a decrease in the contamination of the pasture.

References related to peripartum rise in ewes by breed, type of infection and main topic attended, as well as the variable response studied.

Breed N Infection Preg - Lact Topic FEC PV HV Cells Igs Horm Sp Author
Cross 18 Nat Preg-Lact Season X Procter (1968)
Merino 61 Nat -150 to 60 Season X W O'Sullivan and Donald (1970)
Udah 14 Nat FEC X Van Geldorp and Van Veen (1976)
Mules 20 Nat -42 to 42 FEC X W,I Hg,P W Thomas and Ali (1983)
Florida Native, SC, Barbados, Ram, FD 64 Nat -21 to 56 R-S X Courtney et al. (1984)
Florida Native 76 Nat -21 to 70 R-S X H Courtney et al. (1986)
Merino 70 Nat - Season X L3 Gibbs and Barger (1986)
West African Dwarf 40 Nat Preg-Lact Season X W Agyei et al. (1991)
Greyface ewes (BL x SBF) 28 Einf -84 to 21 R-S X A,G,M Pe Jeffcoate et al. (1992)
Merino 395 Nat 0-42 R-S X L3 Woolaston (1992)
Crosses 44 Nat -14 to 21 R-S X Romjali et al. (1997)
Mens, Horro 2786 Nat -60 to 84 Season X Tembely et al. (1998)
Greyface 30 Nat -42 to 42 Nutrition X I P T Al,Pe W Houdijk et al. (2000)
Barki 18 - Preg-Lact Hemat W,P,Hg Al,Ur,Cr El-Sherif and Assad (2001)
Coopworth 96 Nat-Exp -30 a 84 R-S X W,I McAnulty et al. (2001)
SBF 200 Nat Lact Genetic X W,I Min Bishop and Stear (2001)
Hamp, Rom, WF 27 - 0 to 47 Hormonal Lep Mcfadin et al. (2002)
Merino 120 Nat -52 to 97 Nutrition X W,I Kahn et al. (2003)
Dorper 40 Nat NE Season X Ng'ang'a et al. (2004)
BL x NZR 120 Nat -56 to 48 Nutrition X W T,A Xie et al. (2004)
Santa Ines, IDF 22 Nat -150 to 60 R-S X W H,P E L3 Rocha et al. (2004)
Rom x Aragonesa 32 Exp -42 to 21 Nutrition I H,Hg E Lep W Valderrabano et al. (2006)
Martinik 120 Nat -50 to 50 Curve X H Mahieu and Aumont (2007)
Boutsiko, Chio, cross 33 - -18 to 15 Cells Ma,Ne Theodorou et al. (2007)
Mules 72 Exp -56 to 24 Nutrition X W p AI,Ur,Pe Kidane et al. (2009)
Merino 128 Exp -50 to 42 R-S X E,W,T T,G, W Beasley et al. (2010)
M,A,E
SBF x BFL Exp -24 to 32 Nutrition X W,l AI,Ur,Pe Kidane et al. (2010)
Merino 144 Nat -35 to 21 R-S X L3 Williams et al. (2010b)
Santa Inês, IDF 120 Nat -35 to 49 Nutrition X w H,P E A,G Rocha et al. (2004)
Santa Inês, IDF 120 Exp -35 to 49 Nutrition X w H,P E A,G Rocha et al. (2011)
Merino 2500 Nat 56 to 68 Curve X L3 Goldberg et al. (2012a)
Merino 748 Nat 58 to 68 Genetic Goldberg et al. (2012b)
Merino 83 Exp -50 to 40 Nutrition X E,W,T T Lep W Beasley et al. (2012)
Mules 24 Exp -56 to 31 Nutrition X W,l Pe,Ur,AI Sakkas et al. (2012)
Red Engadine 78 Nat-Exp -13 to 29 Nutrition X L3 Werne et al. (2013)
SC, Dorset x Finnsheep 20 Exp -21 to 21 R-S X H A Bowdridge et al. (2013)
x Ram
Texel 10 No infection -42 to 14 Hormonal H,P,Hg Al, Ur,Ch Zárate Frutos et al. (2014)
Katahdin x Pelibuey 46 Nat -150 to 90 Sel-Treat X w H Gonzàlez-Garduño et al. (2014)
Col creole, Romney, Hamp, Corriedale 43 Nat -150 to 60 Drug X w Vargas-Duarte et al. (2015)
Santa Inès 45 Nat Nutrition X H,P,Hg W David et al. (2015)
Texel 72 Nat -75 to 50 Immun X w A,G Nisbet et al. (2016)
Criollo, Suffolk 53 Exp -28 to 42 R-S X w H E Romero-Escobedo et al. (2016)
Pelibuey 54 Nat 0-75 Sel-Treat X H Arece-García et al. (2017)
Katahdin 931 Nat -20 to 80 Curve X Notter et al. (2017)
Not specified 240 Nat 0 to 90 Sel-Treat X L3 Westers et al. (2017)
Blackbelly 25 Nat -150 to 90 R-S X H,P E A L3 Gonzalez-Garduno et al. (2017)
Bergamasca 70 Nat Nut-Imm H, T Basseto et al. (2018)
Blackbelly 51 Nat -150 to 90 R-S E,W A L3 Gonzalez-Garduno et al. (2018)
Exlana 112 Nat Peak R-S X Vineer et al. (2019)
Texel, IDF 36 Nat -28 to 56 R-S X W H,P Gasparina et al. (2019)
Mule, Cheviot, SBF, Texel 1750 Nat Preg-Lact Season X L3 Hamer et al. (2019)
Crioula Lanada 18 Nat -30 to 120 R-S X W H,P E G L3 Pereira et al. (2020)
German Blackhead 23 Nat -30 to 30 Citometry X E,W Cor,min Ahmed et al. (2020)
Pelibuey 91 Nat 0 to 75 Sel-Treat X W Aguirre-Serrano et al. (2020)

Breed: SC: St. Croix, Ram: Rambouillet, FD: Finnsheep x Dorset, BL: Border Leicester, SBF: Scottish Blackface, Ham: Hampshire, Rom: Romanov, WF: White Face, NZR: New Zealand Romney, IDF: Ile de France, BFL: Bluefaced Leicester, Col creole: Colombian creole, Mules: BFL x SBF, N: Number of ewes. Infection: Nat: By grazing, Exp: Experimental infection. Prg to Lact: Days from pregnancy to lactation. Topic: R-S (Resistant-Susceptibility), Sel-Treat: selective treatment. FEC: Faecal egg count. PV: Productive variables: W: Live weight, I: Feed intake, HV: Hematological variables: H: Hematocrit or packed cell volume, P: Total plasma protein, Hg: hemoglobin. Cells T: Tissue cells, E: Eosinophils, W: White blood cells, Ma: Macrophages, Ne: Neutrophils. Igs: Immunoglobulins: A:IgA, G:IgG, T:Total antibodies. Horm: Hormones: Cor: Cortisol, Al: Albumins, Pe: Pepsinogen, Ur: Urea, Ch: Cholesterol, Min: minerals, Cr: creatinine. Sp: nematode species, L3: infective larvae, W: Count of worms.

Nutrition

In the peripartum period, ewes present an imbalance of nutrients that they require to maintain the final third of gestation and prepare the mammary gland for the next lactation (Barger, 1993; Jones et al., 2012). Since nutritional status is an important factor influencing the parasite–host relationship and the pathogenesis of infections (Valderrábano et al., 2006) and affecting the productive behaviour in ewes (Macarthur et al., 2014), adequate nutrition is a control measure, specifically in the critical stages of the final third of pregnancy and during lactation (Macarthur et al., 2014), that can improve the immune response of sheep (Houdijk et al., 2006; Kyriazakis & Houdijk, 2006). Protein supplementation favours a greater presence of inflammatory cells in the abomasum mucosa, increasing the immune response and the animal’s resistance and resilience to infection (Kyriazakis & Houdijk, 2006; Rocha et al., 2011). Physiologically, it has been found that when supplementing with protein sources, hyperplasia occurs in the abomasum with a greater quantity of leukocytes and mast cells; after antigenic stimulation the mucosal mast cells release their content, making their function effective 21 days after the start of protein supplementation (Houdijk et al., 2006). Another important aspect of protein supplementation is that eosinophils are benefited, as they are a type of granulocyte related to the response to cells that contain protein-rich cytoplasmic granules (Hayward, 2013). However, supplementation can increase food costs (Davies et al., 2005). Results of a sheep-based meta-analysis suggested an important interaction between parasitism and dietary energy and protein consumption (Méndez-Ortíz et al., 2019). Infected animals require more energy to maintain a live weight gain similar to that of non-infected animals. An energy supply in addition to protein is required for the development of immune mechanisms (Toscan et al., 2017).

Feed consumption

Infections in ruminants with GIN are characterised by a reduction in weight gain from 6 to 30% caused, in part, by a decrease in feed consumption (Kahn et al., 1999; Beasley et al., 2012). In parallel, nutritional requirements are increased up to six-fold compared to sheep outside this stage (Houdijk, 2008), which causes a decrease in gastrointestinal motility and a reduction in gastric acid secretion (Louvandini et al., 2006). This low consumption can cause significant protein losses, mainly in infections by blood-sucking nematodes such as H. contortus. According to estimates, in sheep infected with Trichostrongylus colubriformis the losses are around 20 to 125 g of protein depending on infection level (Kahn et al., 1999; Angulo-Cubillán et al., 2007). All this favours the establishment and reproduction of the GIN with repercussions on the growth, productive efficiency and survival of the lambs.

Age

Adult animals are able to respond better than younger ones (Goldberg et al., 2012a). Young animals’ susceptibility is a consequence of their inability to develop a satisfactory immune response (Kahn et al., 1999; Emery et al., 2000; Getachew et al., 2007). They do not acquire effective immunity before 6 or 12 months of age (Williams et al., 2010a), but this improves as age progresses (Miller & Horohov, 2006; Goldberg et al., 2012a). After puberty, females show differential resistance compared to males. Adult sheep tend to have a higher resistance capacity due to the simple fact that they have lived with parasites for a longer time (Courtney et al., 1984; Torres-Acosta & Hoste, 2008) and with constant exposure to parasites and repeated infections, which is demonstrated by the high number of leukocytes (Miller & Horohov, 2006), except when they are in the peripartum period when their immunity is reduced and when they cause greater contamination of the grazing area (Bishop & Stear, 2001).

Type of birth

There is some controversy regarding the effect of the type of birth because with the same feeding plan, lambs from single births have lower EPG values compared to those from a double birth; this is evident from the different related nutritional requirements with the number of products in gestation (Houdijk, 2008). Gruner et al. (1992) and Goldberg et al. (2012a) found that the type of birth had a significant effect, with mothers with multiple births showing higher EPG values than those with single delivery. Woolaston (1992) indicated that those ewes that lost their lambs during lactation had low EPG values. In other study, >90% of the triplet-bearing ewes needed treatment, demonstrating the high treatment risk among ewes with large litter sizes (Aguirre-Serrano et al., 2020).

Season

Under grazing management, the environmental conditions of the season influence the prevalence and relative dominance of some parasite species (Torres-Acosta & Hoste, 2008), as well as the number of infective larvae (L3). The first studies related to the peripartum period reported that the increase in FEC was due to the high humidity in the grasslands being accentuated in the rainy season; in this season is common to find greater amounts of Trichostrongylus sp and Haemonchus sp, and this coincides with the time when ewes are lactating (Van Geldorp & Van Veen, 1976). Later studies indicated that the parasitic eggs remain inhibited during the dry season and are reactivated in the rainy season, causing infection in the sheep when it coincides with the period of low immune response (Ng´ang´a et al., 2004).

Hypobiotic state of the parasite

The hypobiotic state refers to an adaptation phenomenon of the parasite and the host interacting with the environment, particularly with temperature and humidity (Gibbs, 1982). Nematodes in their L4 larval stage enter a period of arrested development or hypobiosis (Miller & Horohov, 2006; Angulo-Cubillán et al., 2007; Getachew et al., 2007), an adaptive mechanism to enable them to survive during extreme environmental conditions and is considered a defence mechanism. There is evidence that, in some regions with extreme temperature conditions, H. contortus worms can survive (Sargison et al., 2007) and increase their longevity, remaining in the host for up to 50 weeks (Getachew et al., 2007). When ewe’s lactation coincides with the hypobiotic state of the parasites, it favours the development of the larval stages, providing a suitable environment for the development of the larval stages of the parasites. When ewe lactation starts, hypobiotic larvae resume development, as a consequence of which worm numbers increase and there is a rise in FEC (Taylor et al., 2016). It is quite probable that the impact of the phenomenon of hypobiosis in tropical and subtropical regions has a lesser effect that in template regions, as it is not well documented in those areas.

Production system

Obviously, when sheep are under a grazing system, the degree of infection is higher than when they remain in stable. However, Silva et al. (2011) compared the peripartum behaviour of goats kept under a conventional system or in stables with goats under grazing conditions, and they didn’t find significant differences between the two production systems. This similar behaviour was attributed to controlled management in both cases, whereas under extensive grazing and with little control the infection could be higher. However, under the same production system, management differences result in different parasitic behaviour (Vineer et al., 2019), which causes each farm to adopt different forms of control, giving priority to sustainable control in order to reduce anthelmintic resistance (Vande et al., 2018).

Conclusions

The genetic selection of resistant individuals is dependent on the heritability (h2), which is moderately inheritable and highly repeatable for FEC. The physiological, immunological and genetic effects that influence the resistance or susceptibility of sheep to GIN infections in the peripartum period are in turn determined by the interaction of various factors, such as genotype or breed, nutrition, age, type of birth, time of year and production system, among others.

Fig. 1

Interaction of estrogenic and lactogenic hormones and nematode faecal egg count in the pregnancy and lactation of hair ewes. Elaborated with the information of several authors (Kann and Denamur, 1973; Convey, 1974; Ranilla et al., 1994; González-Garduño et al., 2014; Miura et al., 2019).
Interaction of estrogenic and lactogenic hormones and nematode faecal egg count in the pregnancy and lactation of hair ewes. Elaborated with the information of several authors (Kann and Denamur, 1973; Convey, 1974; Ranilla et al., 1994; González-Garduño et al., 2014; Miura et al., 2019).

References related to peripartum rise in ewes by breed, type of infection and main topic attended, as well as the variable response studied.

Breed N Infection Preg - Lact Topic FEC PV HV Cells Igs Horm Sp Author
Cross 18 Nat Preg-Lact Season X Procter (1968)
Merino 61 Nat -150 to 60 Season X W O'Sullivan and Donald (1970)
Udah 14 Nat FEC X Van Geldorp and Van Veen (1976)
Mules 20 Nat -42 to 42 FEC X W,I Hg,P W Thomas and Ali (1983)
Florida Native, SC, Barbados, Ram, FD 64 Nat -21 to 56 R-S X Courtney et al. (1984)
Florida Native 76 Nat -21 to 70 R-S X H Courtney et al. (1986)
Merino 70 Nat - Season X L3 Gibbs and Barger (1986)
West African Dwarf 40 Nat Preg-Lact Season X W Agyei et al. (1991)
Greyface ewes (BL x SBF) 28 Einf -84 to 21 R-S X A,G,M Pe Jeffcoate et al. (1992)
Merino 395 Nat 0-42 R-S X L3 Woolaston (1992)
Crosses 44 Nat -14 to 21 R-S X Romjali et al. (1997)
Mens, Horro 2786 Nat -60 to 84 Season X Tembely et al. (1998)
Greyface 30 Nat -42 to 42 Nutrition X I P T Al,Pe W Houdijk et al. (2000)
Barki 18 - Preg-Lact Hemat W,P,Hg Al,Ur,Cr El-Sherif and Assad (2001)
Coopworth 96 Nat-Exp -30 a 84 R-S X W,I McAnulty et al. (2001)
SBF 200 Nat Lact Genetic X W,I Min Bishop and Stear (2001)
Hamp, Rom, WF 27 - 0 to 47 Hormonal Lep Mcfadin et al. (2002)
Merino 120 Nat -52 to 97 Nutrition X W,I Kahn et al. (2003)
Dorper 40 Nat NE Season X Ng'ang'a et al. (2004)
BL x NZR 120 Nat -56 to 48 Nutrition X W T,A Xie et al. (2004)
Santa Ines, IDF 22 Nat -150 to 60 R-S X W H,P E L3 Rocha et al. (2004)
Rom x Aragonesa 32 Exp -42 to 21 Nutrition I H,Hg E Lep W Valderrabano et al. (2006)
Martinik 120 Nat -50 to 50 Curve X H Mahieu and Aumont (2007)
Boutsiko, Chio, cross 33 - -18 to 15 Cells Ma,Ne Theodorou et al. (2007)
Mules 72 Exp -56 to 24 Nutrition X W p AI,Ur,Pe Kidane et al. (2009)
Merino 128 Exp -50 to 42 R-S X E,W,T T,G, W Beasley et al. (2010)
M,A,E
SBF x BFL Exp -24 to 32 Nutrition X W,l AI,Ur,Pe Kidane et al. (2010)
Merino 144 Nat -35 to 21 R-S X L3 Williams et al. (2010b)
Santa Inês, IDF 120 Nat -35 to 49 Nutrition X w H,P E A,G Rocha et al. (2004)
Santa Inês, IDF 120 Exp -35 to 49 Nutrition X w H,P E A,G Rocha et al. (2011)
Merino 2500 Nat 56 to 68 Curve X L3 Goldberg et al. (2012a)
Merino 748 Nat 58 to 68 Genetic Goldberg et al. (2012b)
Merino 83 Exp -50 to 40 Nutrition X E,W,T T Lep W Beasley et al. (2012)
Mules 24 Exp -56 to 31 Nutrition X W,l Pe,Ur,AI Sakkas et al. (2012)
Red Engadine 78 Nat-Exp -13 to 29 Nutrition X L3 Werne et al. (2013)
SC, Dorset x Finnsheep 20 Exp -21 to 21 R-S X H A Bowdridge et al. (2013)
x Ram
Texel 10 No infection -42 to 14 Hormonal H,P,Hg Al, Ur,Ch Zárate Frutos et al. (2014)
Katahdin x Pelibuey 46 Nat -150 to 90 Sel-Treat X w H Gonzàlez-Garduño et al. (2014)
Col creole, Romney, Hamp, Corriedale 43 Nat -150 to 60 Drug X w Vargas-Duarte et al. (2015)
Santa Inès 45 Nat Nutrition X H,P,Hg W David et al. (2015)
Texel 72 Nat -75 to 50 Immun X w A,G Nisbet et al. (2016)
Criollo, Suffolk 53 Exp -28 to 42 R-S X w H E Romero-Escobedo et al. (2016)
Pelibuey 54 Nat 0-75 Sel-Treat X H Arece-García et al. (2017)
Katahdin 931 Nat -20 to 80 Curve X Notter et al. (2017)
Not specified 240 Nat 0 to 90 Sel-Treat X L3 Westers et al. (2017)
Blackbelly 25 Nat -150 to 90 R-S X H,P E A L3 Gonzalez-Garduno et al. (2017)
Bergamasca 70 Nat Nut-Imm H, T Basseto et al. (2018)
Blackbelly 51 Nat -150 to 90 R-S E,W A L3 Gonzalez-Garduno et al. (2018)
Exlana 112 Nat Peak R-S X Vineer et al. (2019)
Texel, IDF 36 Nat -28 to 56 R-S X W H,P Gasparina et al. (2019)
Mule, Cheviot, SBF, Texel 1750 Nat Preg-Lact Season X L3 Hamer et al. (2019)
Crioula Lanada 18 Nat -30 to 120 R-S X W H,P E G L3 Pereira et al. (2020)
German Blackhead 23 Nat -30 to 30 Citometry X E,W Cor,min Ahmed et al. (2020)
Pelibuey 91 Nat 0 to 75 Sel-Treat X W Aguirre-Serrano et al. (2020)

ABOSHADY, H.M., STEAR, M.J., JOHANSSON, A., JONAS, E., BAMBOU, J.C. (2020): Immunoglobulins as biomarkers for gastrointestinal nematodes resistance in small ruminants: A systematic review. Sci Rep, 10(1): 1–14, DOI: 10.1038/s41598-020-64775-xABOSHADY H.M. STEAR M.J. JOHANSSON A. JONAS E. BAMBOU J.C. 2020 Immunoglobulins as biomarkers for gastrointestinal nematodes resistance in small ruminants: A systematic review Sci Rep 10 1 1 14 10.1038/s41598-020-64775-xOpen DOISearch in Google Scholar

AGUIRRE-SERRANO, A.M., OJEDA-ROBERTOS, N., GONZÁLEZ-GARDUÑO, R., PERALTA-TORRES, J.A., LUNA-PALOMERA, C., TORRES-ACOSTA, J.F.J. (2020): Influence of lambing and litter size at birth or weaning on the proportion of Pelibuey ewes treated with an anthelmintic in a targeted selective scheme in the humid tropics, Small Rumin. Res., 184: 106049. DOI: 10.1016/j.smallrumres.2020.106049AGUIRRE-SERRANO A.M. OJEDA-ROBERTOS N. GONZÁLEZ-GARDUÑO R. PERALTA-TORRES J.A. LUNA-PALOMERA C. TORRES-ACOSTA J.F.J. 2020 Influence of lambing and litter size at birth or weaning on the proportion of Pelibuey ewes treated with an anthelmintic in a targeted selective scheme in the humid tropics, Small Rumin Res 184 106049 10.1016/j.smallrumres.2020.106049Open DOISearch in Google Scholar

AGYEI, A.D., SAPONG, D., PROBERT, A.J. (1991): Periparturient rise in faecal nematode egg counts in West African Dwarf sheep in Southern Ghana in the absence of arrested strongyle larvae. Vet. Parasitol., 39(1-2): 79–88. DOI: 10.1016/0304-4017(91)90064-3 AHMED, M.H., WILKENS, M.R., MÖLLER, B., GANTER, M., BREVES, G. (2020): Blood leukocyte composition and function in periparturient ewes kept on different dietary magnesium supply. BMC Vet. Res., 16: 1–14. DOI: 10.1186/s12917-020-02705-9AGYEI A.D. SAPONG D. PROBERT A.J. 1991 Periparturient rise in faecal nematode egg counts in West African Dwarf sheep in Southern Ghana in the absence of arrested strongyle larvae Vet. Parasitol 39 1-2 79 88 10.1016/0304-4017(91)90064-3 AHMED, M.H., WILKENS, M.R., MÖLLER, B., GANTER, M., BREVES, G. (2020): Blood leukocyte composition and function in periparturient ewes kept on different dietary magnesium supply. BMC Vet. Res., 16: 1–14 10.1186/s12917-020-02705-9Open DOISearch in Google Scholar

ALBA-HURTADO, F., MUÑOZ-GUZMÁN, M.A. (2013): Immune responses associated with resistance to haemonchosis in sheep. BioMed Res. Int., 2013: 11. DOI: 10.1155/2013/162158ALBA-HURTADO F. MUÑOZ-GUZMÁN M.A. 2013 Immune responses associated with resistance to haemonchosis in sheep BioMed Res. Int 2013 11 10.1155/2013/162158Open DOISearch in Google Scholar

ALBA-HURTADO, F., ROMERO-ESCOBEDO, E., MUÑOZ-GUZMÁN, M.A., TORRES-HERNÁNDEZ, G., BECERRIL-PÉREZ, C.M. (2010): Comparison of parasitological and productive traits of Criollo lambs native to the central Mexican Plateau and Suffolk lambs experimentally infected with Haemonchus contortus Vet. Parasitol., 172(3-4): 277–282. DOI: 10.1016/j.vetpar.2010.05.001ALBA-HURTADO F. ROMERO-ESCOBEDO E. MUÑOZ-GUZMÁN M.A. TORRES-HERNÁNDEZ G. BECERRIL-PÉREZ C.M. 2010 Comparison of parasitological and productive traits of Criollo lambs native to the central Mexican Plateau and Suffolk lambs experimentally infected with Haemonchus contortus Vet. Parasitol 172 3-4 277 282 10.1016/j.vetpar.2010.05.001Open DOISearch in Google Scholar

ALBUQUERQUE, A.C.A., BASSETTO, C.C., ALMEIDA, F.A., HILDERSLEY, K.A., MCNEILLY, T.N., BRITTON, C., AMARANTE, A.F.T. (2019): Differences in immune responses to Haemonchus contortus infection in the susceptible Ile de France and the resistant Santa Ines sheep under different anthelmintic treatments regimens. Vet. Res., 50(1): 1–12. DOI: 10.1186/s13567-019-0722-3ALBUQUERQUE A.C.A. BASSETTO C.C. ALMEIDA F.A. HILDERSLEY K.A. MCNEILLY T.N. BRITTON C. AMARANTE A.F.T. 2019 Differences in immune responses to Haemonchus contortus infection in the susceptible Ile de France and the resistant Santa Ines sheep under different anthelmintic treatments regimens Vet. Res 50 1 1 12 10.1186/s13567-019-0722-3Open DOISearch in Google Scholar

ALERI, J.W., HINE, B.C., PYMAN, M.F., MANSELL, P.D., WALES, W.J., MALLARD, B., FISHER, A.D. (2016): Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period. Res. Vet. Sci., 108: 8–17. DOI: 10.1016/j.rvsc.2016.07.007ALERI J.W. HINE B.C. PYMAN M.F. MANSELL P.D. WALES W.J. MALLARD B. FISHER A.D. 2016 Periparturient immunosuppression and strategies to improve dairy cow health during the periparturient period Res. Vet. Sci 108 8 17 10.1016/j.rvsc.2016.07.007Open DOISearch in Google Scholar

AMARANTE, A.F.T., BRICARELLO, P.A., HUNTLEY, J.F., MAZZOLIN, L.P., GOMES, J.C. (2005): Relationship of abomasal histology and parasite-specific immunoglobulin A with the resistance to Haemonchus contortus infection in three breeds of sheep. Vet. Parasitol., 128: 99–107. DOI: 10.1016/j.vetpar.2004.11.021AMARANTE A.F.T. BRICARELLO P.A. HUNTLEY J.F. MAZZOLIN L.P. GOMES J.C. 2005 Relationship of abomasal histology and parasite-specific immunoglobulin A with the resistance to Haemonchus contortus infection in three breeds of sheep Vet. Parasitol 128 99 107 10.1016/j.vetpar.2004.11.021Open DOISearch in Google Scholar

ANGULO-CUBILLÁN, F.J., GARCÍA-COIRADAS, L., CUQUERELLA, M., DE LA FUENTE, C., ALUNDA, J.M. (2007): Haemonchus contortus - sheep relationship: A review. Rev. Científ. FCV-LUZ., XVII(6): 577–587. Available in: http://www.redalyc.org/articulo.oa?id=95911668005ANGULO-CUBILLÁN F.J. GARCÍA-COIRADAS L. CUQUERELLA M. DE LA FUENTE C. ALUNDA J.M. 2007 Haemonchus contortus - sheep relationship: A review Rev. Científ. FCV-LUZ XVII 6 577587 Available in http://www.redalyc.org/articulo.oa?id=95911668005Search in Google Scholar

ARECE-GARCÍA, J., LÓPEZ-LEYVA, Y., GONZÁLEZ-GARDUÑO, R., TORRES-HERNÁNDEZ, G., ROJO-RUBIO, R., MARIE-MAGDELEINE, C. (2017): Effect of selective anthelmintic treatments on health and production parameters in Pelibuey ewes during lactation. Trop. Anim. Health Prod., 48(2): 283–287ARECE-GARCÍA J. LÓPEZ-LEYVA Y. GONZÁLEZ-GARDUÑO R. TORRES-HERNÁNDEZ G. ROJO-RUBIO R. MARIE-MAGDELEINE C. 2017 Effect of selective anthelmintic treatments on health and production parameters in Pelibuey ewes during lactation Trop. Anim. Health Prod 48 2 283 287Search in Google Scholar

BARGER, I.A. (1993): Influence of sex and reproductive status on susceptibility of ruminants to nematode parasitism. Int. J. Parasitol., 23(4): 463–469. DOI: 10.1016/0020-7519(93)90034-VBARGER I.A. 1993 Influence of sex and reproductive status on susceptibility of ruminants to nematode parasitism Int. J. Parasitol 23 4 463 469 10.1016/0020-7519(93)90034-VOpen DOISearch in Google Scholar

BASRIPUZI, N.H., SALISI, M.S., ISA, N.M.M., BUSIN, V., CAIRNS, C., JENVEY, C., STEAR, M.J. (2018): Boer goats appear to lack a functional IgA and eosinophil response against natural nematode infection. Vet. Parasitol., 264: 18–25. DOI: 10.1016/j.vetpar.2018.10.014BASRIPUZI N.H. SALISI M.S. ISA N.M.M. BUSIN V. CAIRNS C. JENVEY C. STEAR M.J. 2018 Boer goats appear to lack a functional IgA and eosinophil response against natural nematode infection Vet. Parasitol 264 18 25 10.1016/j.vetpar.2018.10.014Open DOISearch in Google Scholar

BASSETTO, C.C., ALMEIDA, F.A., NEWLANDS, G.F.J., SMITH, W.D., CASTILHOS, A.M., FERNANDES, S., SIQUEIRA, E.R., AMARANTE, A.F.T. (2018): Trials with the Haemonchus vaccine, Barbervax®, in ewes and lambs in a tropical environment: Nutrient supplementation improves protection in periparturient ewes. Vet. Parasitol., 264: 52–57. DOI: 10.1016/j.vetpar.2018.11.006BASSETTO C.C. ALMEIDA F.A. NEWLANDS G.F.J. SMITH W.D. CASTILHOS A.M. FERNANDES S. SIQUEIRA E.R. AMARANTE A.F.T. 2018 Trials with the Haemonchus vaccine, Barbervax®, in ewes and lambs in a tropical environment: Nutrient supplementation improves protection in periparturient ewes Vet. Parasitol 264 52 57 10.1016/j.vetpar.2018.11.006Open DOISearch in Google Scholar

BEASLEY, A., KAHN, L., WINDON, R. (2010): The periparturient relaxation of immunity in Merino ewes infected with Trichostrongylus colubriformis: Parasitological and immunological responses. Vet. Parasitol., 168: 60–70. DOI: 10.1016/j.vetpar.2009.08.028BEASLEY A. KAHN L. WINDON R. 2010 The periparturient relaxation of immunity in Merino ewes infected with Trichostrongylus colubriformis: Parasitological and immunological responses Vet. Parasitol 168 60 70 10.1016/j.vetpar.2009.08.028Open DOISearch in Google Scholar

BEASLEY, A.M., KAHN, L.P., WINDON, R.G. (2012): The influence of reproductive physiology and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode Trichostrongylus colubriformis in Merino ewes. Vet. Parasitol., 188(3-4): 306–324. DOI: 10.1016/j.vetpar.2012.03.022BEASLEY A.M. KAHN L.P. WINDON R.G. 2012 The influence of reproductive physiology and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode Trichostrongylus colubriformis in Merino ewes Vet. Parasitol 188 3-4 306 324 10.1016/j.vetpar.2012.03.022Open DOISearch in Google Scholar

BEH, K.J., MADDOX, J.F. (1996): Prospects for development of genetic markers for resistance to gastrointestinal parasite infection in sheep. Int. J. Parasitol., 26(8-9): 879–897. DOI: 10.1016/S0020-7519(96)80060-9BEH K.J. MADDOX J.F. 1996 Prospects for development of genetic markers for resistance to gastrointestinal parasite infection in sheep Int. J. Parasitol 26 8-9 879 897 10.1016/S0020-7519(96)80060-9Open DOISearch in Google Scholar

BISHOP, S.C., STEAR, M.J. (2001): Inheritance of faecal egg counts during early lactation in Scottish Blackface ewes facing mixed, natural nematode infections. Anim. Sci., 76(6): 389–395. DOI: 10.1017/S1357729800058355BISHOP S.C. STEAR M.J. 2001 Inheritance of faecal egg counts during early lactation in Scottish Blackface ewes facing mixed, natural nematode infections Anim. Sci 76 6 389 395 10.1017/S1357729800058355Open DOISearch in Google Scholar

BISHOP, S.C., MORRIS, C.A. (2007): Genetics of disease resistance in sheep and goats. Small Rumin. Res., 70(1): 48–59. DOI: 10.1016/j.smallrumres.2007.01.006BISHOP S.C. MORRIS C.A. 2007 Genetics of disease resistance in sheep and goats Small Rumin. Res 70 1 48 59 10.1016/j.smallrumres.2007.01.006Open DOISearch in Google Scholar

BOWDRIDGE, S., MACKINNON, K., MCCANN, J.C., ZAJAC, A.M., NOTTER, D.R. (2013): Hair-type sheep generate an accelerated and longer-lived humoral immune response to Haemonchus contortus infection. Vet. Parasitol., 196: 172–178. DOI: 10.1016/j.vetpar.2013.01.008BOWDRIDGE S. MACKINNON K. MCCANN J.C. ZAJAC A.M. NOTTER D.R. 2013 Hair-type sheep generate an accelerated and longer-lived humoral immune response to Haemonchus contortus infection Vet. Parasitol 196 172 178 10.1016/j.vetpar.2013.01.008Open DOISearch in Google Scholar

BOWDRIDGE, S.A., ZAJAC, A.M., NOTTER, D.R. (2015): St. Croix sheep produce a rapid and greater cellular immune response contributing to reduced establishment of Haemonchus contortus Vet. Parasitol., 208(3-4): 204–210. DOI: 10.1016/j.vetpar.2015.01.019BOWDRIDGE S.A. ZAJAC A.M. NOTTER D.R. 2015 St Croix sheep produce a rapid and greater cellular immune response contributing to reduced establishment of Haemonchus contortus Vet. Parasitol 208 3-4 204 210 10.1016/j.vetpar.2015.01.019Open DOISearch in Google Scholar

BRICARELLO, P.A., GENNARI, S.M., OLIVEIRA-SEQUEIRA, T.C.G., VAZ, C.M.S.L., DE GONÇALVES, I.G., ECHEVARRIA, F.A.M. (2004): Worm burden and immunological responses in Corriedale and Crioula Lanada sheep following natural infection with Haemonchus contortus. Small Rumin. Res., 51(1): 75–83. DOI: 10.1016/S09214488(03)00188-3BRICARELLO P.A. GENNARI S.M. OLIVEIRA-SEQUEIRA T.C.G. VAZ C.M.S.L. DE GONÇALVES I.G. ECHEVARRIA F.A.M. 2004 Worm burden and immunological responses in Corriedale and Crioula Lanada sheep following natural infection with Haemonchus contortus Small Rumin. Res 51 1 75 83 10.1016/S09214488(03)00188-3Open DOISearch in Google Scholar

BRICARELLO, P.A., ZAROS, L.G., COUTINHO, L.L., ROCHA, R.A., SILVA, M.B., KOOYMAN, F.N.J., DE VRIES, E., YATSUDA, A.P., AMARANTE, A.F.T. (2008): Immunological responses and cytokine gene expression analysis to Cooperia punctata infections in resistant and susceptible Nelore cattle. Vet. Parasitol., 155(1-2): 95–103. DOI: 10.1016/j.vetpar.2008.03.016BRICARELLO P.A. ZAROS L.G. COUTINHO L.L. ROCHA R.A. SILVA M.B. KOOYMAN F.N.J. DE VRIES E. YATSUDA A.P. AMARANTE A.F.T. 2008 Immunological responses and cytokine gene expression analysis to Cooperia punctata infections in resistant and susceptible Nelore cattle Vet. Parasitol 155 1-2 95 103 10.1016/j.vetpar.2008.03.016Open DOISearch in Google Scholar

CAROPRESE, M., ALBENZIO, M., MARZANO, A., SCHENA, L., ANNICCHIARICO, G., SEVI, A. (2010): Relationship between cortisol response to stress and behavior, immune profile, and production performance of dairy ewes. J. Dairy Sci., 93(6): 2395–2403. DOI: 10.3168/ jds.2009-2604CAROPRESE M. ALBENZIO M. MARZANO A. SCHENA L. ANNICCHIARICO G. SEVI A. 2010 Relationship between cortisol response to stress and behavior, immune profile, and production performance of dairy ewes J. Dairy Sci 93 6 2395 2403 10.3168/jds.2009-2604Open DOISearch in Google Scholar

CASTELLANO, G., WOLTMAN, A.M., PAOLO, F., ROOS, A., DAHA, M.R., KOOTEN, C. VAN (2004): Dendritic cells and complement: at the cross road of innate and adaptive immunity. Mol. Immunol., 41: 133–140. DOI: 10.1016/j.molimm.2004.03.018CASTELLANO G. WOLTMAN A.M. PAOLO F. ROOS A. DAHA M.R. KOOTEN C. VAN 2004 Dendritic cells and complement: at the cross road of innate and adaptive immunity Mol. Immunol 41 133 140 10.1016/j.molimm.2004.03.018Open DOISearch in Google Scholar

CEI, W., SALAH, N., PAUT, C., DUMOULIN, P.-J., ARQUET, R., FÉLICITÉ, Y., ALEXANDRE, G., ARCHIMÉDE, H., BAMBOU, J. (2016): Impact of the post-weaning nutritional history on the response to an experimental Haemonchus contortus infection in Creole goats and Black Belly sheep. Vet. Parasitol., 218: 87–92. DOI: 10.1016/j.vetpar.2016.01.015CEI W. SALAH N. PAUT C. DUMOULIN P.-J. ARQUET R. FÉLICITÉ Y. ALEXANDRE G. ARCHIMÉDE H. BAMBOU J. 2016 Impact of the post-weaning nutritional history on the response to an experimental Haemonchus contortus infection in Creole goats and Black Belly sheep Vet. Parasitol 218 87 92 10.1016/j.vetpar.2016.01.015Open DOISearch in Google Scholar

CHARTIER, C., HOSTE, H., BOUQUET, W., MALPAUX, B., PORS, I., KOCH, C. (1998): Periparturient rise in fecal egg counts associated with prolactin concentration increase in French Alpine dairy goats. Parasitol. Res., 84(10): 806–810. DOI: 10.1007/s004360050492CHARTIER C. HOSTE H. BOUQUET W. MALPAUX B. PORS I. KOCH C. 1998 Periparturient rise in fecal egg counts associated with prolactin concentration increase in French Alpine dairy goats Parasitol. Res 84 10 806 810 10.1007/s004360050492Open DOISearch in Google Scholar

CONVEY, E.M. (1974): Serum hormone concentration in ruminants during mammary growth, lactogenesis, and lactation: A review. J. Dairy Sci., 57(8): 905–917. DOI: 10.3168/jds.S00220302(74)84986-6CONVEY E.M. 1974 Serum hormone concentration in ruminants during mammary growth, lactogenesis, and lactation: A review J. Dairy Sci 57 8 905 917 10.3168/jds.S00220302(74)84986-6Open DOISearch in Google Scholar

COURTNEY, C.H., PARKER, C.F., MCCLURE, K.E., HERD, R.P. (1984): A comparison of the periparturient rise in fecal egg counts of exotic and domestic ewes. Int. J. Parasitol., 14(4): 377–381. DOI: 10.1016/0020-7519(84)90092-4COURTNEY C.H. PARKER C.F. MCCLURE K.E. HERD R.P. 1984 A comparison of the periparturient rise in fecal egg counts of exotic and domestic ewes Int. J. Parasitol 14 4 377 381 10.1016/0020-7519(84)90092-4Open DOISearch in Google Scholar

COURTNEY, C.H., PARKER, C.F., MCCLURE, K.E., HERD, R.P. (1985): Resistance of exotic and domestic lambs to experimental infection with Haemonchus contortus Int. J. Parasitol., 15(1): 101–109. DOI: 10.1016/0020-7519(85)90107-9COURTNEY C.H. PARKER C.F. MCCLURE K.E. HERD R.P. 1985 Resistance of exotic and domestic lambs to experimental infection with Haemonchus contortus Int. J. Parasitol 15 1 101 109 10.1016/0020-7519(85)90107-9Open DOISearch in Google Scholar

COURTNEY, C.H., GESSNER, R., SHOLZ, S.R., LOGGIN, P.E. (1986): The periparturient rise in fecal egg counts in three strains of Florida Native ewes and its value in predicting resistance of lambs to Haemonchus contortus Int. J. Parasitol., 16(3): 185–189. DOI: 10.1016/0020-7519(86)90042-1COURTNEY C.H. GESSNER R. SHOLZ S.R. LOGGIN P.E. 1986 The periparturient rise in fecal egg counts in three strains of Florida Native ewes and its value in predicting resistance of lambs to Haemonchus contortus Int. J. Parasitol 16 3 185 189 10.1016/0020-7519(86)90042-1Open DOISearch in Google Scholar

DAVID, C.M.G., DA COSTA, R.L.D., PARREN, G.A.E., RUA, M.A.S., NORDI, E.C.P., OKAMOTO, F., PAZ, C.C.P. (2015): Sugarcane and mulberry silage supplementation of sheep during the peripartum period. Trop. Anim. Health Prod., 47(4): 765–772. DOI: 10.1007/s11250-015-0791-xDAVID C.M.G. DA COSTA R.L.D. PARREN G.A.E. RUA M.A.S. NORDI E.C.P. OKAMOTO F. PAZ C.C.P. 2015 Sugarcane and mulberry silage supplementation of sheep during the peripartum period Trop. Anim. Health Prod 47 4 765 772 10.1007/s11250-015-0791-xOpen DOISearch in Google Scholar

DAVIES, G., STEAR, M.J., BISHOP, S.C. (2005): Genetic relationships between indicator traits and nematode parasite infection levels in 6-month-old lambs. Anim. Sci., 80(2): 143–150. DOI: 10.1079/ASC41290143DAVIES G. STEAR M.J. BISHOP S.C. 2005 Genetic relationships between indicator traits and nematode parasite infection levels in 6-month-old lambs Anim. Sci 80 2 143 150 10.1079/ASC41290143Open DOISearch in Google Scholar

DERVISHI, E., URIARTE, J., VALDERRÁBANO, J., CALVO, J.H. (2011): Structural and functional characterisation of the ovine interferon gamma (IFNG) gene: its role in nematode resistance in Rasa Aragonesa ewes. Vet. Immunol. Immunopathol., 141(1-2): 100–108. DOI: 10.1016/j.vetimm.2011.02.013DERVISHI E. URIARTE J. VALDERRÁBANO J. CALVO J.H. 2011 Structural and functional characterisation of the ovine interferon gamma (IFNG) gene: its role in nematode resistance in Rasa Aragonesa ewes Vet. Immunol. Immunopathol 141 1-2 100 108 10.1016/j.vetimm.2011.02.013Open DOISearch in Google Scholar

DÍAZ-RIVERA, P., TORRES-HERNÁNDEZ, G., OSORIO-ARCE, M., PÉREZ-HERNÁNDEZ, P., BECERRIL-PÉREZ, C., HERRERA-HARO, J. (2000): Resistance to gastrointestinal parasites in Florida, Pelibuey and crossbred sheep in the mexican tropics. Agrociencia, 34(1): 13–20DÍAZ-RIVERA P. TORRES-HERNÁNDEZ G. OSORIO-ARCE M. PÉREZ-HERNÁNDEZ P. BECERRIL-PÉREZ C. HERRERA-HARO J. 2000 Resistance to gastrointestinal parasites in Florida, Pelibuey and crossbred sheep in the mexican tropics Agrociencia 34 1 13 20Search in Google Scholar

DÍAZ, S., RIPOLI, M.V. PERAL-GARCÍA, P., GIOVAMBATTISTA, G. (2005): Marcadores genéticos para resistencia y susceptibilidad a enfermedades infecciosas en animales domésticos [Genetic markers for susceptibility and resistance to infectious diseases in farm animals]. Analecta Vet., 25(1): 40–52. Available in: http://sedici.unlp.edu.ar/handle/10915/11177 (In Spanish)DÍAZ S. RIPOLI M.V. PERAL-GARCÍA P. GIOVAMBATTISTA G. 2005 Marcadores genéticos para resistencia y susceptibilidad a enfermedades infecciosas en animales domésticos [Genetic markers for susceptibility and resistance to infectious diseases in farm animals] Analecta Vet 25 1 40 52 Available in http://sedici.unlp.edu.ar/handle/10915/11177 (In Spanish)Search in Google Scholar

DOMINIK, S. (2005): Quantitative trait loci for internal nematode resistance in sheep: a review. Gen. Sel. Evol., 37(Suppl 1): 83–96. DOI: 10.1051/gse:2004027DOMINIK S. 2005 Quantitative trait loci for internal nematode resistance in sheep: a review Gen. Sel. Evol 37 Suppl 1 83 96 10.1051/gse:2004027Open DOISearch in Google Scholar

EL-SHERIF, M.M.A., ASSAD, F. (2001): Changes in some blood constituents of Barki ewes during pregnancy and lactation under semi arid conditions. Small Rumin. Res., 40(3): 269–277. DOI: 10.1016/S0921-4488(01)00174-2EL-SHERIF M.M.A. ASSAD F. 2001 Changes in some blood constituents of Barki ewes during pregnancy and lactation under semi arid conditions Small Rumin. Res 40 3 269 277 10.1016/S0921-4488(01)00174-2Open DOISearch in Google Scholar

EMERY, D.L., MCLURE, S.J., DAVEY, R.J. (2000): Protection of Merino lambs against Haemonchus contortus by trickle infection of neonates, Parasitol. Int., 49(2): 165–170. DOI: 10.1016/S1383-5769(00)00038-6EMERY D.L. MCLURE S.J. DAVEY R.J. 2000 Protection of Merino lambs against Haemonchus contortus by trickle infection of neonates, Parasitol Int 49 2 165 170 10.1016/S1383-5769(00)00038-6Open DOISearch in Google Scholar

FINKELMAN, F.D., SHEA-DONOHUE, T., GOLDHILL, J., SULLIVAN, C.A., MORRIS, S.C., KATHLEEN, B., GAUSE, W.C., URBAN, J.F. (1997): Cytokine regulation of host defense against parasitic gastrointestinal nematodes: Lessons from studies with rodent models. Annual Rev. Immunol., 15: 505–533. DOI: 10.1146/annurev.immunol.15.1.505 FLEMING, M.W., CONRAD, S.D. (1989): Effects of exogenous progesterone and/or prolactin on Haemonchus contortus infections in ovariectomized ewes. Vet. Parasitol., 34(1-2): 57–62FINKELMAN F.D. SHEA-DONOHUE T. GOLDHILL J. SULLIVAN C.A. MORRIS S.C. KATHLEEN B. GAUSE W.C. URBAN J.F. 1997 Cytokine regulation of host defense against parasitic gastrointestinal nematodes: Lessons from studies with rodent models Annual Rev. Immunol 15 505 533 10.1146/annurev.immunol.15.1.505 FLEMING, M.W., CONRAD, S.D. (1989): Effects of exogenous progesterone and/or prolactin on Haemonchus contortus infections in ovariectomized ewes. Vet. Parasitol., 34(1-2): 57–62Open DOISearch in Google Scholar

FTHENAKIS, G.C., MAVROGIANNI, V.S., GALLIDIS, E., PAPA DOPOULOS, E. (2015): Interactions between parasitic infections and reproductive efficiency in sheep. Vet. Parasitol., 208: 56–66. DOI: 10.1016/j.vetpar.2014.12.017FTHENAKIS G.C. MAVROGIANNI V.S. GALLIDIS E. PAPA DOPOULOS E. 2015 Interactions between parasitic infections and reproductive efficiency in sheep Vet. Parasitol 208 56 66 10.1016/j.vetpar.2014.12.017Open DOISearch in Google Scholar

FUJITA, T., ENDO, Y., NONAKA, M. (2004): Primitive complement system-recognition and activation. Mol. Immunol., 41(2-3): 103–111. DOI: 10.1016/j.molimm.2004.03.026FUJITA T. ENDO Y. NONAKA M. 2004 Primitive complement system-recognition and activation Mol. Immunol 41 2-3 103 111 10.1016/j.molimm.2004.03.026Open DOISearch in Google Scholar

GASPARINA, J.M., FONSECA, L., LODDI, M.M., DE SOUZA M.A., DA ROCHA, R.A. (2019): Resistance of ewes to gastrointestinal nematode infections during the peripartum and dry periods and the performance of their lambs. Rev. Bras. Saude Prod. Animal., 20: 1–11. DOI: 10.1590/S1519-9940200282019GASPARINA J.M. FONSECA L. LODDI M.M. DE SOUZA M.A. DA ROCHA R.A. 2019 Resistance of ewes to gastrointestinal nematode infections during the peripartum and dry periods and the performance of their lambs Rev. Bras. Saude Prod. Animal 20 1 11 10.1590/S1519-9940200282019Open DOISearch in Google Scholar

GAULY, M., KRAUS, M., VERVELDE, L., VAN LEEUWEN, M.A.W., ERHARDT, G. (2002): Estimating genetic differences in natural resistance in Rhön and Merinoland sheep following experimental Haemonchus contortus infection. Vet. Parasitol., 106(1): 55–67. DOI: 10.1016/S0304-4017(02)00028-6GAULY M. KRAUS M. VERVELDE L. VAN LEEUWEN M.A.W. ERHARDT G. 2002 Estimating genetic differences in natural resistance in Rhön and Merinoland sheep following experimental Haemonchus contortus infection Vet. Parasitol 106 1 55 67 10.1016/S0304-4017(02)00028-6Open DOISearch in Google Scholar

GETACHEW, T., DORCHIES, P., JACQUIET, P. (2007): Trends and challenges in the effective and sustainable control of Haemonchus contortus infection in sheep. Review. Parasite, 14(1): 3–14. DOI: 10.1051/parasite/2007141003GETACHEW T. DORCHIES P. JACQUIET P. 2007 Trends and challenges in the effective and sustainable control of Haemonchus contortus infection in sheep Review. Parasite 14 1 3 14 10.1051/parasite/2007141003Open DOISearch in Google Scholar

GIBBS, H.C. (1982): Mechanisms of survival of nematode parasites with emphasis on hypobiosis. Vet. Parasitol., 1(1): 25–48. DOI: 10.1016/0304-4017(82)90119-4GIBBS H.C. 1982 Mechanisms of survival of nematode parasites with emphasis on hypobiosis Vet. Parasitol 1 1 25 48 10.1016/0304-4017(82)90119-4Open DOISearch in Google Scholar

GIBBS, H.C., BARGER, I.A. (1986): Haemonchus contortus and other trichostrongylid infections in parturient, lactating and dry ewes. Vet. Parasitol., 22(1-2): 57–66. DOI: 10.1016/0304-4017(86)90007-5 GOLDBERG, V., CIAPESONI, G., AGUILAR, I. (2012a): Genetic parameters for nematode resistance in periparturient ewes and post-weaning lambs in Uruguayan Merino sheep. Livest. Sci., 147(1-3): 181–187. DOI: 10.1016/j.livsci.2012.05.003GIBBS H.C. BARGER I.A. 1986 Haemonchus contortus and other trichostrongylid infections in parturient, lactating and dry ewes Vet. Parasitol 22 1-2 57 66 10.1016/0304-4017(86)90007-5 GOLDBERG, V., CIAPESONI, G., AGUILAR, I. (2012a): Genetic parameters for nematode resistance in periparturient ewes and post-weaning lambs in Uruguayan Merino sheep. Livest. Sci., 147(1-3): 181–187 10.1016/j.livsci.2012.05.003Open DOISearch in Google Scholar

GOLDBERG, V., CIAPESONI, G., AGUILAR, I. (2012b): Modelling the faecal worm egg count curve during the periparturient period in Uruguayan Merino sheep. Spanish J. Agric. Res., 10(4): 986–992. DOI: 10.5424/sjar/2012104-3256GOLDBERG V. CIAPESONI G. AGUILAR I. 2012b Modelling the faecal worm egg count curve during the periparturient period in Uruguayan Merino sheep Spanish J. Agric. Res 10 4 986 992 10.5424/sjar/2012104-3256Open DOISearch in Google Scholar

GÓMEZ-MUÑOZ, M.T., CUQUERELLA, M., GÓMEZ-IGLESIAS, L.A., MÉNDEZ, S., FERNÁNDEZ-PÉREZ, F.J., DE LA FUENTE, C., ALUNDA, J.M. (1999): Serum antibody response of Castellana sheep to Haemonchus contortus infection and challenge: relationship to abomasal worm burdens. Vet. Parasitol., 1(4): 281–293. DOI: 10.1016/S0304-4017(98)00260-XGÓMEZ-MUÑOZ M.T. CUQUERELLA M. GÓMEZ-IGLESIAS L.A. MÉNDEZ S. FERNÁNDEZ-PÉREZ F.J. DE LA FUENTE C. ALUNDA J.M. 1999 Serum antibody response of Castellana sheep to Haemonchus contortus infection and challenge: relationship to abomasal worm burdens Vet. Parasitol 1 4 281 293 10.1016/S0304-4017(98)00260-XOpen DOISearch in Google Scholar

GONÇALVES, T.C., ALENCAR, M.M., GIGLIOTI, R., BILHASSI, T.B., OLIVEIRA, H.N., RABELO, M.D., ESTEVES, S.N., OLIVEIRA, M.C.S. (2018): Resistance of sheep from different genetic groups to gastrointestinal nematodes in the state of São Paulo, Brazil. Small Rumin. Res., 166: 7–11. DOI: 10.1016/j.smallrumres.2018.07.003GONÇALVES T.C. ALENCAR M.M. GIGLIOTI R. BILHASSI T.B. OLIVEIRA H.N. RABELO M.D. ESTEVES S.N. OLIVEIRA M.C.S. 2018 Resistance of sheep from different genetic groups to gastrointestinal nematodes in the state of São Paulo, Brazil Small Rumin. Res 166 7 11 10.1016/j.smallrumres.2018.07.003Open DOISearch in Google Scholar

GONZÁLEZ-GARDUÑO, R., TORRES-ACOSTA, J.F.J., CHAY-CANUL, A.J. (2014): Susceptibility of hair sheep ewes to nematode parasitism during pregnancy and lactation in a selective anthelmintic treatment scheme under tropical conditions. Res. Vet. Sci., 96(3): 487–492. DOI: 10.1016/j.rvsc.2014.03.001GONZÁLEZ-GARDUÑO R. TORRES-ACOSTA J.F.J. CHAY-CANUL A.J. 2014 Susceptibility of hair sheep ewes to nematode parasitism during pregnancy and lactation in a selective anthelmintic treatment scheme under tropical conditions Res. Vet. Sci 96 3 487 492 10.1016/j.rvsc.2014.03.001Open DOISearch in Google Scholar

GONZÁLEZ GARDUÑO, R., LÓPEZ ARELLANO, M.E., CONDE FELIPE, M.M., MENDOZA DE GIVES, P., AGUILAR MARCELINO, L., JASSO DÍAZ, G. (2017): Immune and haematological parameters of Blackbelly ewes infected with gastrointestinal nematodes. Rev. Colomb. Cienc. Pec., 30: 219–230. DOI: 10.17533/udea.rccp.v30n3a05GONZÁLEZ GARDUÑO R. LÓPEZ ARELLANO M.E. CONDE FELIPE M.M. MENDOZA DE GIVES P. AGUILAR MARCELINO L. JASSO DÍAZ G. 2017 Immune and haematological parameters of Blackbelly ewes infected with gastrointestinal nematodes Rev. Colomb. Cienc. Pec 30 219 230 10.17533/udea.rccp.v30n3a05Open DOISearch in Google Scholar

GONZÁLEZ-GARDUÑO, R., MENDOZA-DE GIVES, P., LÓPEZ-ARELLANO, M.E., AGUILAR-MARCELINO, L., TORRES-HERNÁNDEZ, G., OJEDA-ROBERTOS, N.F., TORRES-ACOSTA, J.F.J. (2018): Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes¨. Exp. Parasitol., 193: 20–26. DOI: 10.1016/j.exppara.2018.08.003GONZÁLEZ-GARDUÑO R. MENDOZA-DE GIVES P. LÓPEZ-ARELLANO M.E. AGUILAR-MARCELINO L. TORRES-HERNÁNDEZ G. OJEDA-ROBERTOS N.F. TORRES-ACOSTA J.F.J. 2018 Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes¨ Exp. Parasitol 193 20 26 10.1016/j.exppara.2018.08.003Open DOISearch in Google Scholar

GONZÁLEZ-GARDUÑO, R., LÓPEZ-ARELLANO, M.E., TORRES-HERNÁNDEZ, G., OLIVA-HERNÁNDEZ, J., HINOJOSA-CUÉLLAR, J.A. (2019): Assessment of acquired resistance in previously infected lambs with gastrointestinal nematodes in a tropical climate. Indian J. Anim. Res., 53(9): 1223–1228. DOI: 10.18805/ijar.B-928GONZÁLEZ-GARDUÑO R. LÓPEZ-ARELLANO M.E. TORRES-HERNÁNDEZ G. OLIVA-HERNÁNDEZ J. HINOJOSA-CUÉLLAR J.A. 2019 Assessment of acquired resistance in previously infected lambs with gastrointestinal nematodes in a tropical climate Indian J. Anim. Res 53 9 1223 1228 10.18805/ijar.B-928Open DOISearch in Google Scholar

GOOD, B., HANRAHAN, J.P., CROWLEY, B.A., MULCAHY , G. (2006): Texel sheep are more resistant to natural nematode challenge than Suffolk sheep based on faecal egg count and nematode burden. Vet. Parasitol., 136(3-4): 317–327. DOI: 10.1016/j.vetpar.2005.12.001 GRUNER, L., BOUIX, J., CABARET, J., BOULARD, C., CORTET, J., SAUVE, C., MOLENAT, G., CALAMEL, M. (1992): Effect of genetic type, lactation and management on helminth infection of ewes in an intensive grazing system on irrigated pasture. Int. J. Parasitol., 22(7): 919–925. DOI: 10.1016/0020-7519(92)90048-PGOOD B. HANRAHAN J.P. CROWLEY B.A. MULCAHY G. 2006 Texel sheep are more resistant to natural nematode challenge than Suffolk sheep based on faecal egg count and nematode burden Vet. Parasitol 136 3-4 317 327 10.1016/j.vetpar.2005.12.001 GRUNER, L., BOUIX, J., CABARET, J., BOULARD, C., CORTET, J., SAUVE, C., MOLENAT, G., CALAMEL, M. (1992): Effect of genetic type, lactation and management on helminth infection of ewes in an intensive grazing system on irrigated pasture. Int. J. Parasitol., 22(7): 919–925 10.1016/0020-7519(92)90048-POpen DOISearch in Google Scholar

GUTIÉRREZ-AMÉZQUITA, R.A., MORALES-MONTOR, J., MUÑOZ-GUZMÁN, M.A., NAVA-CASTRO, K.E., RAMÍREZ-ÁLVAREZ, H., CUENCA-VERDE, C., MORENO-MENDOZA, N.A., CUÉLLAR-ORDAZ, J.A., ALBA-HURTADO, F. (2017): Progesterone inhibits the in vitro L3/L4 molting process in Haemonchus contortus. Vet. Parasitol., 248: 48–53. DOI: 10.1016/j.vetpar.2017.10.011GUTIÉRREZ-AMÉZQUITA R.A. MORALES-MONTOR J. MUÑOZ-GUZMÁN M.A. NAVA-CASTRO K.E. RAMÍREZ-ÁLVAREZ H. CUENCA-VERDE C. MORENO-MENDOZA N.A. CUÉLLAR-ORDAZ J.A. ALBA-HURTADO F. 2017 Progesterone inhibits the in vitro L3/L4 molting process in Haemonchus contortus Vet. Parasitol 248 48 53 10.1016/j.vetpar.2017.10.011Open DOISearch in Google Scholar

HAMER, K., MCINTYRE, J., MORRISON, A.A., JENNINGS, A., KELLY, R.F., LEESON, S., BARTLEY, D.J., CHAUDHRY, U., BUSIN, V., SARGISON, N. (2019): The dynamics of ovine gastrointestinal nematode infections within ewe and lamb cohorts on three Scottish sheep farms. Prev. Vet. Med., 171: 104752. DOI: 10.1016/j.prevetmed.2019.104752HAMER K. MCINTYRE J. MORRISON A.A. JENNINGS A. KELLY R.F. LEESON S. BARTLEY D.J. CHAUDHRY U. BUSIN V. SARGISON N. 2019 The dynamics of ovine gastrointestinal nematode infections within ewe and lamb cohorts on three Scottish sheep farms Prev. Vet. Med 171 104752 10.1016/j.prevetmed.2019.104752Open DOISearch in Google Scholar

HASSAN, M., GOOD, B., HANRAHAN, J.P., CAMPION, D., SAYERS, G., MULCAHY, G., SWEENEY, T. (2011): The dynamic influence of the DRB1*1101 allele on the resistance of sheep to experimental Teladorsagia circumcincta infection. Vet. Res. 42(1): 1–10. DOI: 10.1186/1297-9716-42-46HASSAN M. GOOD B. HANRAHAN J.P. CAMPION D. SAYERS G. MULCAHY G. SWEENEY T. 2011 The dynamic influence of the DRB1*1101 allele on the resistance of sheep to experimental Teladorsagia circumcincta infection Vet. Res 42 1 1 10 10.1186/1297-9716-42-46Open DOISearch in Google Scholar

HAYWARD, A.D. (2013): Causes and consequences of intra- and inter-host heterogeneity in defence against nematodes. Parasite Immunol., 35(11): 362–373. DOI: 10.1111/pim.12054HAYWARD A.D. 2013 Causes and consequences of intra- and inter-host heterogeneity in defence against nematodes Parasite Immunol 35 11 362 373 10.1111/pim.12054Open DOISearch in Google Scholar

HENDAWY, S.H.M. (2018): Immunity to gastrointestinal nematodes in ruminants: effector cell mechanisms and cytokines. J. Parasitic Diseases, 42(4): 471–482. DOI: 10.1007/s12639-018-1023-xHENDAWY S.H.M. 2018 Immunity to gastrointestinal nematodes in ruminants: effector cell mechanisms and cytokines J. Parasitic Diseases 42 4 471 482 10.1007/s12639-018-1023-xOpen DOISearch in Google Scholar

HERNÁNDEZ, J.N., HERNÁNDEZ, A., STEAR, M., CONDE-FELIPE, M., RODRÍGUEZ, E., PIEDRAFITA, D., GONZÁLEZ, J.F. (2016): Potential role for mucosal IgA in modulating Haemonchus contortus adult worm infection in sheep. Vet. Parasitol., 223: 153–158. DOI: 10.1016/j.vetpar.2016.04.022HERNÁNDEZ J.N. HERNÁNDEZ A. STEAR M. CONDE-FELIPE M. RODRÍGUEZ E. PIEDRAFITA D. GONZÁLEZ J.F. 2016 Potential role for mucosal IgA in modulating Haemonchus contortus adult worm infection in sheep Vet. Parasitol 223 153 158 10.1016/j.vetpar.2016.04.022Open DOISearch in Google Scholar

HOBY, S., SCHWARZENBERGER, F., DOHERR, M.G., ROBERT, N., WALZER, C. (2006): Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra. Vet. Parasitol., 138(3-4): 337–348. DOI: 10.1016/j.vetpar.2006.01.028HOBY S. SCHWARZENBERGER F. DOHERR M.G. ROBERT N. WALZER C. 2006 Steroid hormone related male biased parasitism in chamois, Rupicapra rupicapra rupicapra Vet. Parasitol 138 3-4 337 348 10.1016/j.vetpar.2006.01.028Open DOISearch in Google Scholar

HOHENHAUS, M.A., JOSEY, M.J., DOBSON, C., OUTTERIDGE, P.M. (1998): The eosinophil leucocyte, a phenotypic marker of resistance to nematode parasites, is associated with calm behaviour in sheep. Immunol. Cell Biol., 76: 153–158. DOI: 10.1046/j.1440-1711.1998.00727.xHOHENHAUS M.A. JOSEY M.J. DOBSON C. OUTTERIDGE P.M. 1998 The eosinophil leucocyte, a phenotypic marker of resistance to nematode parasites, is associated with calm behaviour in sheep Immunol. Cell Biol 76 153 158 10.1046/j.1440-1711.1998.00727.xOpen DOISearch in Google Scholar

HOSTE, H., CHARTIER, C. (1993): Comparison of the effects on milk production of concurrent infection with Haemonchus contortus and Trichostrongylus colubriformis in high-and low-producing dairy goats. Am. J. Vet. Res., 54(11): 1886–1893HOSTE H. CHARTIER C. 1993 Comparison of the effects on milk production of concurrent infection with Haemonchus contortus and Trichostrongylus colubriformis in high-and low-producing dairy goats Am. J. Vet. Res 54 11 1886 1893Search in Google Scholar

HOUDIJK, J.G.M., KYRIAZAKIS, I., JACKSON, F., HUNTLEY, J.F., COOP, R.L. (2000): Can an increased intake of metabolizable protein affect the periparturient relaxation in immunity against Teladorsagia circumcincta in sheep?. Vet. Parasitol., 91(1-2): 43–62. DOI: 10.1016/S0304-4017(00)00255-7HOUDIJK J.G.M. KYRIAZAKIS I. JACKSON F. HUNTLEY J.F. COOP R.L. 2000 Can an increased intake of metabolizable protein affect the periparturient relaxation in immunity against Teladorsagia circumcincta in sheep? Vet. Parasitol 91 1-2 43 62 10.1016/S0304-4017(00)00255-7Open DOISearch in Google Scholar

HOUDIJK, J.G.M., JACKSON, F., COOP, R.L., KYRIAZAKIS, I. (2006): Rapid improvement of immunity to Teladorsagia circumcincta is achieved through a reduction in the demand for protein in lactating ewes. Int. J. Parasitol., 36(2): 219–227. DOI: 10.1016/j.ijpara.2005.09.014HOUDIJK J.G.M. JACKSON F. COOP R.L. KYRIAZAKIS I. 2006 Rapid improvement of immunity to Teladorsagia circumcincta is achieved through a reduction in the demand for protein in lactating ewes Int. J. Parasitol 36 2 219 227 10.1016/j.ijpara.2005.09.014Open DOISearch in Google Scholar

HOUDIJK, J.G.M. (2008): Influence of periparturient nutritional demand on resistance to parasites in livestock. Parasite Immunol., 30(2): 113–121. DOI: 10.1111/j.1365-3024.2008.00992.xHOUDIJK J.G.M. 2008 Influence of periparturient nutritional demand on resistance to parasites in livestock Parasite Immunol 30 2 113 121 10.1111/j.1365-3024.2008.00992.xOpen DOISearch in Google Scholar

INGHAM, A., REVERTER, A., WINDON, R., HUNT, P., MENZIES, M. (2008): Gastrointestinal nematode challenge induces some conserved gene expression changes in the gut mucosa of genetically resistant sheep. Int. J. Parasitol., 38(3-4): 431–442. DOI: 10.1016/j.ijpara.2007.07.012INGHAM A. REVERTER A. WINDON R. HUNT P. MENZIES M. 2008 Gastrointestinal nematode challenge induces some conserved gene expression changes in the gut mucosa of genetically resistant sheep Int. J. Parasitol 38 3-4 431 442 10.1016/j.ijpara.2007.07.012Open DOISearch in Google Scholar

INGVARTSEN, K.L., BOISCLAIR, Y.R. (2001): Leptin and the regulation of food intake, energy homeostasis and immunity with special focus on periparturient ruminants. Domestic Anim. Endocrinol., 21(4): 215–250. DOI: 10.1016/S0739-7240(02)00119-4INGVARTSEN K.L. BOISCLAIR Y.R. 2001 Leptin and the regulation of food intake, energy homeostasis and immunity with special focus on periparturient ruminants Domestic Anim. Endocrinol 21 4 215 250 10.1016/S0739-7240(02)00119-4Open DOISearch in Google Scholar

JEFFCOATE, I.A., WEDRYCHOWICZ, H., FISHWICK, G., DUNLOP, E.M., DUNCAN, J.L., HOLMES, P.H. (1992): Pathophysiology of the periparturient egg rise in sheep: a possible role for IgA. Res. Vet. Sci., 53(2): 212–218. DOI: 10.1016/0034-5288(92)90112-FJEFFCOATE I.A. WEDRYCHOWICZ H. FISHWICK G. DUNLOP E.M. DUNCAN J.L. HOLMES P.H. 1992 Pathophysiology of the periparturient egg rise in sheep: a possible role for IgA Res. Vet. Sci 53 2 212 218 10.1016/0034-5288(92)90112-FOpen DOISearch in Google Scholar

JONES, L., SAKKAS, P., HOUDIJK, J., KNOX, D., KYRIAZAKIS, I. (2012): Amelioration of the periparturient relaxation of immunity to parasites through a reduction in mammalian reproductive effort. Int. J. Parasitol., 42: 127–134. DOI: 10.1016/j.ijpara.2012.09.010JONES L. SAKKAS P. HOUDIJK J. KNOX D. KYRIAZAKIS I. 2012 Amelioration of the periparturient relaxation of immunity to parasites through a reduction in mammalian reproductive effort Int. J. Parasitol 42 127 134 10.1016/j.ijpara.2012.09.010Open DOISearch in Google Scholar

JONSSON, N.N., FORTES, M.R.S., PIPER, E.K., VANKAN, D.M., CISNEROS, J.P.J. WITTEK, T. (2013): Comparison of metabolic, hematological, and peripheral blood leukocyte cytokine profiles of dairy cows and heifers during the periparturient period. J. Dairy Sci., 96(4): 2283–2292. DOI: 10.3168/jds.2012-6173JONSSON N.N. FORTES M.R.S. PIPER E.K. VANKAN D.M. CISNEROS J.P.J. WITTEK T. 2013 Comparison of metabolic, hematological, and peripheral blood leukocyte cytokine profiles of dairy cows and heifers during the periparturient period J. Dairy Sci 96 4 2283 2292 10.3168/jds.2012-6173Open DOISearch in Google Scholar

KAHN, L., KNOX, M., GRAY, G. (1999): Enhancing immunity to nematode parasites in pregnant and lactating sheep through nutrition and genetic selection. Recent Adv. Anim. Nut. Australia, 12: 15–22KAHN L. KNOX M. GRAY G. 1999 Enhancing immunity to nematode parasites in pregnant and lactating sheep through nutrition and genetic selection Recent Adv. Anim. Nut. Australia 12 15 22Search in Google Scholar

KANN, G., DENAMUR, R. (1973): Possible role of prolactin during the oestrus cycle and gestation in the ewe. J. Reprod. Fertility., 39: 473–483KANN G. DENAMUR R. 1973 Possible role of prolactin during the oestrus cycle and gestation in the ewe J. Reprod. Fertility 39 473 483Search in Google Scholar

KAHN, L.P., KNOX, M.R., GRAY, G.D., LEA, J.M., WALKDEN-BROWN, S.W. (2003): Enhancing immunity to nematode parasites in single-bearing Merino ewes through nutrition and genetic selection. Vet. Parasitol., 112(3): 211–225. DOI: 10.1016/S0304-4017(02)00438-7KAHN L.P. KNOX M.R. GRAY G.D. LEA J.M. WALKDEN-BROWN S.W. 2003 Enhancing immunity to nematode parasites in single-bearing Merino ewes through nutrition and genetic selection Vet. Parasitol 112 3 211 225 10.1016/S0304-4017(02)00438-7Open DOISearch in Google Scholar

KARROW, N.A., GOLIBOSKI, K., STONOS, N., SCHENKEL, F., PEREGRINE, A. (2014): Review: Genetics of helminth resistance in sheep. Canadian J. Anim. Sci., 94(1): 1–9. DOI: 10.4141/CJAS2013-036 KEANE, O.M., ZADISSA, A., WILSON, T., HYNDMAN, D.L., GREER, G.J., BAIRD, D.B., MCCULLOCH, A.F., CRAWFORD, A.M., MCEWAN, J.C. (2006): Gene expression profiling of Naïve sheep genetically resistant and susceptible to gastrointestinal nematodes. BMC Genomics, 7: 1–12. DOI: 10.1186/1471-2164-7-42KARROW N.A. GOLIBOSKI K. STONOS N. SCHENKEL F. PEREGRINE A. 2014 Review: Genetics of helminth resistance in sheep Canadian J. Anim. Sci 94 1 1 9 10.4141/CJAS2013-036 KEANE, O.M., ZADISSA, A., WILSON, T., HYNDMAN, D.L., GREER, G.J., BAIRD, D.B., MCCULLOCH, A.F., CRAWFORD, A.M., MCEWAN, J.C. (2006): Gene expression profiling of Naïve sheep genetically resistant and susceptible to gastrointestinal nematodes. BMC Genomics, 7: 1–12. 10.1186/1471-2164-7-42Open DOISearch in Google Scholar

KIDANE, A., HOUDIJK, J., ATHANASIADOU, S., TOLKAMP, B., KYRIAZAKIS, I. (2010): Nutritional sensitivity of periparturient resistance to nematode parasites in two breeds of sheep with different nutrient demands. British J. Nutr., 104(10): 1477–1486. DOI: 10.1017/S0007114510002503KIDANE A. HOUDIJK J. ATHANASIADOU S. TOLKAMP B. KYRIAZAKIS I. 2010 Nutritional sensitivity of periparturient resistance to nematode parasites in two breeds of sheep with different nutrient demands British J. Nutr 104 10 1477 1486 10.1017/S0007114510002503Open DOISearch in Google Scholar

KIDANE, A., HOUDIJK, J.G., TOLKAMP, B.J., ATHANASIADOU, S., KYRIAZAKIS, I. (2009): Consequences of infection pressure and protein nutrition on periparturient resistance to Teladorsagia circumcincta and performance in ewes. Vet. Parasitol., 165(1-2): 78–87. DOI: 10.1016/j.vetpar.2009.06.039KIDANE A. HOUDIJK J.G. TOLKAMP B.J. ATHANASIADOU S. KYRIAZAKIS I. 2009 Consequences of infection pressure and protein nutrition on periparturient resistance to Teladorsagia circumcincta and performance in ewes Vet. Parasitol 165 1-2 78 87 10.1016/j.vetpar.2009.06.039Open DOISearch in Google Scholar

KIM, D., YAMAGISHI, N., DEVKOTA, B., FURUHAMA, K. (2012): Effects of cortisol secreted via a 12-h infusion of adrenocorticotropic hormone on mineral homeostasis and bone metabolism in ovariectomized cows. Domestic Anim. Endocrinol., 43(3): 264–269. DOI: 10.1016/j.domaniend.2012.04.002KIM D. YAMAGISHI N. DEVKOTA B. FURUHAMA K. 2012 Effects of cortisol secreted via a 12-h infusion of adrenocorticotropic hormone on mineral homeostasis and bone metabolism in ovariectomized cows Domestic Anim. Endocrinol 43 3 264 269 10.1016/j.domaniend.2012.04.002Open DOISearch in Google Scholar

KLION, A.D., NUTMAN, T.B. (2004): Current perspectives The role of eosinophils in host defense against helminth parasites. J. Allergy Clin. Immunol., 113(1): 30–37. DOI: 10.1016/j.jaci.2003.10.050KLION A.D. NUTMAN T.B. 2004 Current perspectives The role of eosinophils in host defense against helminth parasites J. Allergy Clin. Immunol 113 1 30 37 10.1016/j.jaci.2003.10.050Open DOISearch in Google Scholar

KYRIAZAKIS, I., HOUDIJK, J. (2006): Immunonutrition: nutritional control of parasites. Small Rumin. Res., 62(1-2): 79–82. DOI: 10.1016/j.smallrumres.2005.07.036KYRIAZAKIS I. HOUDIJK J. 2006 Immunonutrition: nutritional control of parasites Small Rumin. Res 62 1-2 79 82 10.1016/j.smallrumres.2005.07.036Open DOISearch in Google Scholar

LALRAMHLUNA, M., BORDOLOI, G., PANDIT, S., BAIDYA, S., JOARDAR, S.N., PATRA, A.K., JAS, R. (2020): Parasitological and immunological response to Haemonchus contortus infection: Comparison between resistant Garole and susceptible Sahabadi sheep. Vet. Parasitol., Regional Studies and Reports, 22: 100477. DOI: 10.1016/j.vprsr.2020.100477LALRAMHLUNA M. BORDOLOI G. PANDIT S. BAIDYA S. JOARDAR S.N. PATRA A.K. JAS R. 2020 Parasitological and immunological response to Haemonchus contortus infection: Comparison between resistant Garole and susceptible Sahabadi sheep Vet. Parasitol., Regional Studies and Reports 22 100477 10.1016/j.vprsr.2020.100477Open DOISearch in Google Scholar

LIN, Y.S., ZHOU, H., FORREST, R.H.J., FRAMPTON, C.M., BURROWS, L.E.R., HICKFORD, J.G.H. (2016): Association between variation in faecal egg count for a natural mixed field-challenge of nematode parasites and TLR4 variation. Vet. Parasitol., 218: 5–9. DOI: 10.1016/j.vetpar.2016.01.004LIN Y.S. ZHOU H. FORREST R.H.J. FRAMPTON C.M. BURROWS L.E.R. HICKFORD J.G.H. 2016 Association between variation in faecal egg count for a natural mixed field-challenge of nematode parasites and TLR4 variation Vet. Parasitol 218 5 9 10.1016/j.vetpar.2016.01.004Open DOISearch in Google Scholar

LIPI, E., DO RÊGO L, M.L., HAMAD M, A.H., AIRES, A.R., COOP, R.L., JACKSON, F., SUTTLE, N.F. (2013): Effects of parasitism on cellular immune response in sheep experimentally infected with Haemonchus contortus Vet. Parasitol., 196(1-2): 230–234. DOI: 10.1016/j.vetpar.2013.02.014LIPI E. DO RÊGO L M.L. HAMAD M A.H. AIRES A.R. COOP R.L. JACKSON F. SUTTLE N.F. 2013 Effects of parasitism on cellular immune response in sheep experimentally infected with Haemonchus contortus Vet. Parasitol 196 1-2 230 234 10.1016/j.vetpar.2013.02.014Open DOISearch in Google Scholar

LOUVANDINI, H., VELOSO, C.F.M., PALUDO, G.R., DELL’PORTO, A., GENNARI, S.M., MCMANUS, C.M. (2006): Influence of protein supplementation on the resistance and resilience on young hair sheep naturally infected with gastrointestinal nematodes during rainy and dry seasons. Vet. Parasitol., 137(1-2): 103–111. DOI: 10.1016/j.vetpar.2006.01.004LOUVANDINI H. VELOSO C.F.M. PALUDO G.R. DELL’PORTO A. GENNARI S.M. MCMANUS C.M. 2006 Influence of protein supplementation on the resistance and resilience on young hair sheep naturally infected with gastrointestinal nematodes during rainy and dry seasons Vet. Parasitol 137 1-2 103 111 10.1016/j.vetpar.2006.01.004Open DOISearch in Google Scholar

MACARTHUR, F.A., KAHN, L.P., WINDON, R.G. (2014): The influence of dietary manipulations and gastrointestinal nematodes on twin-bearing merino ewes and determinants of lamb survival. Livest. Sci., 167(1): 342–352. DOI: 10.1016/j.livsci.2014.05.019MACARTHUR F.A. KAHN L.P. WINDON R.G. 2014 The influence of dietary manipulations and gastrointestinal nematodes on twin-bearing merino ewes and determinants of lamb survival Livest. Sci 167 1 342 352 10.1016/j.livsci.2014.05.019Open DOISearch in Google Scholar

MAHIEU, M., AUMONT, G. (2007): Periparturient rise in Martinik Hair Sheep and perspectives for gastrointestinal nematode control. Trop. Anim. Health Prod., 39(6): 387–390. DOI: 10.1007/s11250007-9029-xMAHIEU M. AUMONT G. 2007 Periparturient rise in Martinik Hair Sheep and perspectives for gastrointestinal nematode control Trop. Anim. Health Prod 39 6 387 390 10.1007/s11250007-9029-xOpen DOISearch in Google Scholar

MAZA-LOPEZ, J., PACHECO-ARMENTA, M.J., REYES-GUERRERO, D.E., OLMEDO-JUÁREZ, A., GONZÁLEZ-GARDUÑO, R., OLAZARÁN-JENKINS, S., LÓPEZ-ARELLANO, M.E. (2020): Immune response related to Pelibuey sheep naturally infected with gastrointestinal nematodes in a tropical region of Mexico. Vet. Parasitol., Regional Studies and Reports. 21: 100422. DOI: 10.1016/j.vprsr.2020.100422MAZA-LOPEZ J. PACHECO-ARMENTA M.J. REYES-GUERRERO D.E. OLMEDO-JUÁREZ A. GONZÁLEZ-GARDUÑO R. OLAZARÁN-JENKINS S. LÓPEZ-ARELLANO M.E. 2020 Immune response related to Pelibuey sheep naturally infected with gastrointestinal nematodes in a tropical region of Mexico Vet. Parasitol., Regional Studies and Reports 21 100422 10.1016/j.vprsr.2020.100422Open DOISearch in Google Scholar

MCANULTY, R.W., FAMILTON, A.S., SEDCOLE, R.D., SYKES, A.R. (2001): Changes in the resistance of the ewe to infection with Teladorsagia circumcincta during late pregnancy and lactation. Anim. Sci., 72(1): 159–168. DOI: 10.1017/S135772980005565XMCANULTY R.W. FAMILTON A.S. SEDCOLE R.D. SYKES A.R. 2001 Changes in the resistance of the ewe to infection with Teladorsagia circumcincta during late pregnancy and lactation Anim. Sci 72 1 159 168 10.1017/S135772980005565XOpen DOISearch in Google Scholar

MCFA DIN, E.L., MORRISON, C.D., BUF, P.R., WHITLEY, N.C., KEISLER, D.H. (2002): Leptin concentrations in periparturient ewes and their subsequent offspring, J. Anim. Sci., 80: 738–743. DOI: 10.2527/2002.803738xMCFA DIN E.L. MORRISON C.D. BUF P.R. WHITLEY N.C. KEISLER D.H. 2002 Leptin concentrations in periparturient ewes and their subsequent offspring, J Anim. Sci 80 738 743 10.2527/2002.803738xOpen DOISearch in Google Scholar

MEEUSEN, E.N.T., BALIC, A., BOWLES, V. (2005): Cells, cytokines and other molecules associated with rejection of gastrointestinal nematode parasites. Vet. Immunol. Immunopathol., 108: 121–125. DOI: 10.1016/j.vetimm.2005.07.002MEEUSEN E.N.T. BALIC A. BOWLES V. 2005 Cells, cytokines and other molecules associated with rejection of gastrointestinal nematode parasites Vet. Immunol. Immunopathol 108 121 125 10.1016/j.vetimm.2005.07.002Open DOISearch in Google Scholar

MÉNDEZ-ORTÍZ, F.A., SANDOVAL-CASTRO, C.A., VARGAS-MAGAÑA, J.J., SARMIENTO-FRANCO, L., TORRES-ACOSTA, J.F.J., VENTURA-CORDERO, J. (2019): Impact of gastrointestinal parasitism on dry matter intake and live weight gain of lambs: A meta-analysis to estimate the metabolic cost of gastrointestinal nematodes. Vet. Parasitol., 265: 1–6. DOI: 10.1016/j.vetpar.2018.11.008MÉNDEZ-ORTÍZ F.A. SANDOVAL-CASTRO C.A. VARGAS-MAGAÑA J.J. SARMIENTO-FRANCO L. TORRES-ACOSTA J.F.J. VENTURA-CORDERO J. 2019 Impact of gastrointestinal parasitism on dry matter intake and live weight gain of lambs: A meta-analysis to estimate the metabolic cost of gastrointestinal nematodes Vet. Parasitol 265 1 6 10.1016/j.vetpar.2018.11.008Open DOISearch in Google Scholar

MILLER, J.E., HOROHOV, D.W. (2006): Immunological aspects of nematode parasite control in sheep. J. Anim. Sci., 84(Suppl): 124–132. DOI: 10.2527/2006.8413_supplE124xMILLER J.E. HOROHOV D.W. 2006 Immunological aspects of nematode parasite control in sheep J. Anim. Sci 84 Suppl 124 132 10.2527/2006.8413_supplE124xOpen DOISearch in Google Scholar

MIURA, H., YAMAZAKI, T., KIKUCHI, M., SAKAGUCHI, M. (2019): Plasma steroid hormone concentrations and their relationships in Suffolk ewes during gestation and parturition. Anim. Sci. J., 90(11): 1426–1431. DOI: 10.1111/asj.13286MIURA H. YAMAZAKI T. KIKUCHI M. SAKAGUCHI M. 2019 Plasma steroid hormone concentrations and their relationships in Suffolk ewes during gestation and parturition Anim. Sci. J 90 11 1426 1431 10.1111/asj.13286Open DOISearch in Google Scholar

MOREAU, E., CHAUVIN, A. (2010): Immunity against helminths: Interactions with the host and the intercurrent infections. J. Biomedicine Biotechnol., 2010(428593): 1–9. DOI: 10.1155/2010/428593 MORTEO-GÓMEZ, R., GONZÁLEZ-GARDUÑO, R., TORRES-HERNÁNDEZ, G., NUNCIO-OCHOA, G., BECERRIL-PÉREZ, C.M., GALLEGOS-SÁNCHEZ, J., ARANDA-IBAÑEZ, E. (2004): Effect of the phenotypic variation in the resistance of Pelibuey lambs to the infestation with gastrointestinal nematodes. Agrociencia, 38(4): 395–404MOREAU E. CHAUVIN A. 2010 Immunity against helminths: Interactions with the host and the intercurrent infections J. Biomedicine Biotechnol 2010 428593 1 9 10.1155/2010/428593 MORTEO-GÓMEZ, R., GONZÁLEZ-GARDUÑO, R., TORRES-HERNÁNDEZ, G., NUNCIO-OCHOA, G., BECERRIL-PÉREZ, C.M., GALLEGOS-SÁNCHEZ, J., ARANDA-IBAÑEZ, E. (2004): Effect of the phenotypic variation in the resistance of Pelibuey lambs to the infestation with gastrointestinal nematodes. Agrociencia, 38(4): 395–404Open DOISearch in Google Scholar

MUGAMBI, J., AUDHO, J., BAKER, R. (2005): Evaluation of the phenotypic performance of a Red Maasai and Dorper double backcross resource population: natural pasture challenge with gastrointestinal nematode parasites. Small Rumin. Res., 56: 239–251. DOI: 10.1016/j.smallrumres.2004.06.003MUGAMBI J. AUDHO J. BAKER R. 2005 Evaluation of the phenotypic performance of a Red Maasai and Dorper double backcross resource population: natural pasture challenge with gastrointestinal nematode parasites Small Rumin. Res 56 239 251 10.1016/j.smallrumres.2004.06.003Open DOISearch in Google Scholar

MUÑOZ-GUZMÁN, M.A., CUÉLLAR-ORDAZ, J.A., VALDIVIA-ANDA, A.G., BUENDÍA-JIMÉNEZ, J.A., ALBA-HURTADO, F. (2006): Correlation of parasitological and immunological parameters in sheep with high and low resistance to haemonchosis, Canadian J. Anim. Sci., 86: 363–371. DOI: 10.4141/A06-010MUÑOZ-GUZMÁN M.A. CUÉLLAR-ORDAZ J.A. VALDIVIA-ANDA A.G. BUENDÍA-JIMÉNEZ J.A. ALBA-HURTADO F. 2006 Correlation of parasitological and immunological parameters in sheep with high and low resistance to haemonchosis, Canadian J Anim. Sci 86 363 371 10.4141/A06-010Open DOISearch in Google Scholar

MURPHY, L., PATHAK, A.K., CATTADORI, I.M. (2013): A co-infection with two gastrointestinal nematodes alters host immune responses and only partially parasite dynamics. Parasite Immunol., 35: 421–432. DOI: 10.1111/pim.12045MURPHY L. PATHAK A.K. CATTADORI I.M. 2013 A co-infection with two gastrointestinal nematodes alters host immune responses and only partially parasite dynamics Parasite Immunol 35 421 432 10.1111/pim.12045Open DOISearch in Google Scholar

NG´ANG´A, C., MUNYUA, W., MAINGI, N., KANYARI, P. (2004): Ocurrence of peri-parturient rise in trichostrongylid nematode egg output in Dorper ewes in a semi-arid area of Kajiado District of Kenya. Acta Trop., 92: 213–218. DOI: 10.1016/j.actatropica.2004.05.016 NISBET, A.J., MCNEILLY, T.N., GREER, A.W., BARTLEY, Y., OLIVER, E.M., SMITH, S., PALAREA-ALBALADEJO, J., MATTHEWS, J.B. (2016): Protection of ewes against Teladorsagia circumcincta infection in the periparturient period by vaccination with recombinant antigens. Vet. Parasitol., 228: 130–136. DOI: 10.1016/j.vetpar.2016.09.002NG´ANG´A C. MUNYUA W. MAINGI N. KANYARI P. 2004 Ocurrence of peri-parturient rise in trichostrongylid nematode egg output in Dorper ewes in a semi-arid area of Kajiado District of Kenya Acta Trop 92 213 218 10.1016/j.actatropica.2004.05.016 NISBET, A.J., MCNEILLY, T.N., GREER, A.W., BARTLEY, Y., OLIVER, E.M., SMITH, S., PALAREA-ALBALADEJO, J., MATTHEWS, J.B. (2016): Protection of ewes against Teladorsagia circumcincta infection in the periparturient period by vaccination with recombinant antigens. Vet. Parasitol., 228: 130–136. 10.1016/j.vetpar.2016.09.002Open DOISearch in Google Scholar

NOTTER, D.R., BURKE, J.M., MILLER, J.E., MORGAN, J.L.M. (2017): Factors affecting fecal egg counts in periparturient Katahdin ewes and their lambs. J. Anim. Sci., 95(1): 103–112. DOI: 10.2527/jas2016.0955NOTTER D.R. BURKE J.M. MILLER J.E. MORGAN J.L.M. 2017 Factors affecting fecal egg counts in periparturient Katahdin ewes and their lambs J. Anim. Sci 95 1 103 112 10.2527/jas2016.0955Open DOISearch in Google Scholar

O’SULLIVAN, B.M., DONALD, A.D. (1970): A field study of nematode parasite populations in the lactating ewe. Parasitology, 61(2): 301–315. DOI: 10.1017/S0031182000041135O’SULLIVAN B.M. DONALD A.D. 1970 A field study of nematode parasite populations in the lactating ewe Parasitology 61 2 301 315 10.1017/S0031182000041135Open DOISearch in Google Scholar

O’SULLIVAN, B.M., DONALD, A.D. (1973): Responses to infection with Haemonchus contortus and Trichostrongylus colubriformis in ewes of different reproductive status, Int. J. Parasitol., 3: 521–530. DOI: 10.1016/0020-7519(73)90049-0O’SULLIVAN B.M. DONALD A.D. 1973 Responses to infection with Haemonchus contortus and Trichostrongylus colubriformis in ewes of different reproductive status, Int J. Parasitol 3 521 530 10.1016/0020-7519(73)90049-0Open DOISearch in Google Scholar

OBIDIKE, I.R., AKA, L.O., OKAFOR, C.I. (2009): Time-dependant peri-partum haematological, biochemical and rectal temperature changes in West African dwarf ewes. Small Rumin. Res., 82(1): 53–57. DOI: 10.1016/j.smallrumres.2009.01.012OBIDIKE I.R. AKA L.O. OKAFOR C.I. 2009 Time-dependant peri-partum haematological, biochemical and rectal temperature changes in West African dwarf ewes Small Rumin. Res 82 1 53 57 10.1016/j.smallrumres.2009.01.012Open DOISearch in Google Scholar

PALOMO-COUOH, J.G., AGUILAR-CABALLERO, A.J., TORRES-ACOSTA, J.F.J., GONZÁLEZ-GARDUÑO, R. (2017): Comparing the phenotypic susceptibility of Pelibuey and Katahdin female lambs against natural gastrointestinal nematode infections under hot humid tropical conditions. Parasitol. Res., 116(6). DOI: 10.1007/s00436-0175437-7PALOMO-COUOH J.G. AGUILAR-CABALLERO A.J. TORRES-ACOSTA J.F.J. GONZÁLEZ-GARDUÑO R. 2017 Comparing the phenotypic susceptibility of Pelibuey and Katahdin female lambs against natural gastrointestinal nematode infections under hot humid tropical conditions Parasitol. Res 116 6 10.1007/s00436-0175437-7Open DOISearch in Google Scholar

PEREIRA, F.C., LONGO, C., CASTILHO, C., LEME, D.P., SEUGLING, J., BASSETTO, C.C., AMARANTE, A.F.T., BRICARELLO, P.A. (2020): Peripartum phenomenon in Crioula Lanada sheep susceptible and resistant to gastrointestinal nematodes. Frontiers Vet. Sci., 7: 1–8. DOI: 10.3389/fvets.2020.00598PEREIRA F.C. LONGO C. CASTILHO C. LEME D.P. SEUGLING J. BASSETTO C.C. AMARANTE A.F.T. BRICARELLO P.A. 2020 Peripartum phenomenon in Crioula Lanada sheep susceptible and resistant to gastrointestinal nematodes Frontiers Vet. Sci 7 1 8 10.3389/fvets.2020.00598Open DOISearch in Google Scholar

PETTIT, J.J., JACKSON, F., ROCCHI, M., HUNTLEY, J.F. (2005): The relationship between responsiveness against gastrointestinal nematodes in lambs and the numbers of circulating IgE-bearing cells. Vet. Parasitol., 134(1-2): 131–139. DOI: 10.1016/j.vetpar.2005.06.014PETTIT J.J. JACKSON F. ROCCHI M. HUNTLEY J.F. 2005 The relationship between responsiveness against gastrointestinal nematodes in lambs and the numbers of circulating IgE-bearing cells Vet. Parasitol 134 1-2 131 139 10.1016/j.vetpar.2005.06.014Open DOISearch in Google Scholar

PHILLIPPS, H.R., YIP, S.H., GRATTAN, D.R. (2020): Patterns of prolactin secretion. Mol. Cel. Endocrinol., 502(110679): 1–15. DOI: 10.1016/j.mce.2019.110679PHILLIPPS H.R. YIP S.H. GRATTAN D.R. 2020 Patterns of prolactin secretion Mol. Cel. Endocrinol 502 110679 1 15 10.1016/j.mce.2019.110679Open DOISearch in Google Scholar

PROCTER, B.G., GIBBS, H.C. (1968): Studies on the spring rise phenomenon in ovine helminthiasis. I. Spring rise in stabled sheep. Can. J. Comp. Med. Vet. Sci., 32(1): 359–365PROCTER B.G. GIBBS H.C. 1968 Studies on the spring rise phenomenon in ovine helminthiasis I. Spring rise in stabled sheep. Can. J. Comp. Med. Vet. Sci 32 1 359 365Search in Google Scholar

RAHMAN, W.A., COLLINS, G.H. (1992): An association of faecal egg counts and prolactin concentrations in sera of periparturient Angora goats. Vet. Parasitol., 43(1-2): 85–91. DOI: 10.1016/03044017(92)90051-ARAHMAN W.A. COLLINS G.H. 1992 An association of faecal egg counts and prolactin concentrations in sera of periparturient Angora goats Vet. Parasitol 43 1-2 85 91 10.1016/03044017(92)90051-AOpen DOISearch in Google Scholar

RANILLA, M., SULON, J., CARRO, M., MANTECÓN, A., BECKERS, J. (1994): Plasmatic profiles of pregnancy-associatted glycoprotein and progesterone levels during gestation in Churra and Merino sheep. Theriogenololy, 42(3): 537–545RANILLA M. SULON J. CARRO M. MANTECÓN A. BECKERS J. 1994 Plasmatic profiles of pregnancy-associatted glycoprotein and progesterone levels during gestation in Churra and Merino sheep Theriogenololy 42 3 537 545Search in Google Scholar

ROCHA, R.A., AMARANTE, A.F.T., BRICARELLO, P.A. (2004): Comparison of the susceptibility of Santa Inês and Ile de France ewes to nematode parasitism around parturition and during lactation. Small Rumin. Res., 55(1-3): 65–75. DOI: 10.1016/j.smallrumres.2003.12.004ROCHA R.A. AMARANTE A.F.T. BRICARELLO P.A. 2004 Comparison of the susceptibility of Santa Inês and Ile de France ewes to nematode parasitism around parturition and during lactation Small Rumin. Res 55 1-3 65 75 10.1016/j.smallrumres.2003.12.004Open DOISearch in Google Scholar

ROCHA, R.A., BRICARELLO, P.A., SILVA, M.B., HOUDIJK, J.G.M., ALMEIDA, F.A., CARDIA, D.F.F., AMARANTE, A.F.T.D. (2011): Influence of protein supplementation during late pregnancy and lactation on the resistance of Santa Ines and Ile de France ewes to Haemonchus contortus Vet. Parasitol., 181(2-4): 229–238. DOI: 10.1016/j.vetpar.2011.03.055ROCHA R.A. BRICARELLO P.A. SILVA M.B. HOUDIJK J.G.M. ALMEIDA F.A. CARDIA D.F.F. AMARANTE A.F.T.D. 2011 Influence of protein supplementation during late pregnancy and lactation on the resistance of Santa Ines and Ile de France ewes to Haemonchus contortus Vet. Parasitol 181 2-4 229 238 10.1016/j.vetpar.2011.03.055Open DOISearch in Google Scholar

ROMERO-ESCOBEDO, E., TORRES-HERNÁNDEZ, G., BECERRIL-PÉREZ, C.M., ALARCÓN-ZÚÑIGA, B., APODACA-SARABIA, C.A., DÍAZ-RIVERA, P. (2018): A comparison of criollo and Suffolk ewes for resistance to Haemonchus contortus during the periparturient period. J. Appl. Anim. Res., 46(1): 17–23. DOI: 10.1080/09712119.2016.1252378 ROMJALI, E., BATUBARA, A., PANDEY, V.S., GATENBY, R.M. (2000): Peri-parturient rise in faecal strongyle egg counts of different genotypes of sheep in North Sumatra , Indonesia. Vet. Parasitol., 68(1997): 191–196. DOI: 10.1016/s0304-4017(96)01008-4ROMERO-ESCOBEDO E. TORRES-HERNÁNDEZ G. BECERRIL-PÉREZ C.M. ALARCÓN-ZÚÑIGA B. APODACA-SARABIA C.A. DÍAZ-RIVERA P. 2018 A comparison of criollo and Suffolk ewes for resistance to Haemonchus contortus during the periparturient period J. Appl. Anim. Res 46 1 17 23 10.1080/09712119.2016.1252378 ROMJALI, E., BATUBARA, A., PANDEY, V.S., GATENBY, R.M. (2000): Peri-parturient rise in faecal strongyle egg counts of different genotypes of sheep in North Sumatra , Indonesia. Vet. Parasitol., 68(1997): 191–196. 10.1016/s0304-4017(96)01008-4Open DOISearch in Google Scholar

ROWE, A., MCMASTER, K., EMERY, D., SANGSTER, N. (2008): Haemonchus contortus infection in sheep: Parasite fecundity correlates with worm size and host lymphocyte counts. Vet. Parasitol., 153(34): 285–293. DOI: 10.1016/j.vetpar.2008.01.040ROWE A. MCMASTER K. EMERY D. SANGSTER N. 2008 Haemonchus contortus infection in sheep: Parasite fecundity correlates with worm size and host lymphocyte counts Vet. Parasitol 153 34 285 293 10.1016/j.vetpar.2008.01.040Open DOISearch in Google Scholar

SADDIQI, H.A., IQBAL, Z., KHAN, M.N., MUHAMMAD, G. (2010): Comparative resistance of sheep breeds to Haemonchus contortus in a natural pasture infection. Int. J. Agric. Biol., 12(5): 739–743.SADDIQI H.A. IQBAL Z. KHAN M.N. MUHAMMAD G. 2010 Comparative resistance of sheep breeds to Haemonchus contortus in a natural pasture infection Int. J. Agric. Biol 12 5 739 743Search in Google Scholar

SAKKAS, P., HOUDIJK, J.G.M., ATHANASIADOU, S., KYRIAZAKIS, I. (2012): Sensitivity of periparturient breakdown of immunity to parasites to dietary protein source. J. Anim. Sci., 90(11): 3954–3962. DOI: 10.2527/jas.2011-4829SAKKAS P. HOUDIJK J.G.M. ATHANASIADOU S. KYRIAZAKIS I. 2012 Sensitivity of periparturient breakdown of immunity to parasites to dietary protein source J. Anim. Sci 90 11 3954 3962 10.2527/jas.2011-4829Open DOISearch in Google Scholar

SARGISON, N.D., WILSON, D.J., BARTLEY, D.J., PENNY, C.D., JACKSON, F. (2007): Haemonchosis and teladorsagiosis in a Scottish sheep flock putatively associated with the overwintering of hypobiotic fourth stage larvae. Vet. Parasitol., 147(3-4): 326–331. DOI: 10.1016/j.vetpar.2007.04.011SARGISON N.D. WILSON D.J. BARTLEY D.J. PENNY C.D. JACKSON F. 2007 Haemonchosis and teladorsagiosis in a Scottish sheep flock putatively associated with the overwintering of hypobiotic fourth stage larvae Vet. Parasitol 147 3-4 326 331 10.1016/j.vetpar.2007.04.011Open DOISearch in Google Scholar

SAYERS, G., GOOD, B., HANRAHAN, J.P., O’DONOVAN, J., MULCAHY, G., SWEENEY, T. (2007): Breed differences in mucosal and systemic antibody response to nematode infection in sheep: an important role for IgE? Parasitology, 135: 71–80. DOI: 10.1017/S0031182007003630SAYERS G. GOOD B. HANRAHAN J.P. O’DONOVAN J. MULCAHY G. SWEENEY T. 2007 Breed differences in mucosal and systemic antibody response to nematode infection in sheep: an important role for IgE? Parasitology 135 71 80 10.1017/S0031182007003630Open DOISearch in Google Scholar

SAYERS, G., SWEENEY, T. (2005): Gastrointestinal nematode infection in sheep–a review of the alternatives to anthelmintics in parasite control. Anim. Health Res. Rev., 6(2): 159–171. DOI: 10.1079/AHR2005108SAYERS G. SWEENEY T. 2005 Gastrointestinal nematode infection in sheep–a review of the alternatives to anthelmintics in parasite control Anim. Health Res. Rev 6 2 159 171 10.1079/AHR2005108Open DOISearch in Google Scholar

SILVA, J.B., FAGUNDES, G.M., FONSECA, A.H. (2011): Dynamics of gastrointestinal parasitoses in goats kept in organic and conventional production systems in Brazil. Small Rumin. Res., 98(1-3): 35–38. DOI: 10.1016/j.smallrumres.2011.03.014SILVA J.B. FAGUNDES G.M. FONSECA A.H. 2011 Dynamics of gastrointestinal parasitoses in goats kept in organic and conventional production systems in Brazil Small Rumin. Res 98 1-3 35 38 10.1016/j.smallrumres.2011.03.014Open DOISearch in Google Scholar

SIMPSON, H.V. (2000): Pathophysiology of abomasal parasitism: is the host or parasite responsible? The Vet. J., 160(3): 177–191. DOI: 10.1053/tvjl.2000.0491SIMPSON H.V. 2000 Pathophysiology of abomasal parasitism: is the host or parasite responsible? The Vet J 160 3 177 191 10.1053/tvjl.2000.0491Open DOISearch in Google Scholar

SRÉTER, T., KASSAI, T., TAKÁCS, E. (1994): The heritability and specificity of responsiveness to infection with Haemonchus contortus in sheep. Int. J. Parasitol., 24(6): 871–876. DOI: 10.1016/00207519(94)90013-2SRÉTER T. KASSAI T. TAKÁCS E. 1994 The heritability and specificity of responsiveness to infection with Haemonchus contortus in sheep Int. J. Parasitol 24 6 871 876 10.1016/00207519(94)90013-2Open DOISearch in Google Scholar

STEAR, M., MURRAY, M. (1994): Genetic resistance to parasitic disease: Particularly of resistance in ruminants to gastrointestinal nematodes. Vet. Parasitol., 54(1-3): 161–176. DOI: 10.1016/03044017(94)90089-2STEAR M. MURRAY M. 1994 Genetic resistance to parasitic disease: Particularly of resistance in ruminants to gastrointestinal nematodes Vet. Parasitol 54 1-3 161 176 10.1016/03044017(94)90089-2Open DOISearch in Google Scholar

SYKES, A.R. (2010): Host immune responses to nematodes : benefit or cost? Implications for future development of sustainable methods of control. Rev. Bras. Zoot., 39(S): 376–382. DOI: 10.1590/S1516-35982010001300041SYKES A.R. 2010 Host immune responses to nematodes : benefit or cost? Implications for future development of sustainable methods of control Rev. Bras. Zoot 39 S 376 382 10.1590/S1516-35982010001300041Open DOISearch in Google Scholar

TAYLOR, M., SARGISON, N., HOWE, M. (2016): Dosing ewes at lambing time. Vet. Record., 178(15): 377–378. DOI: 10.1136/vr.i1978TAYLOR M. SARGISON N. HOWE M. 2016 Dosing ewes at lambing time Vet. Record 178 15 377 378 10.1136/vr.i1978Open DOISearch in Google Scholar

TEMBELY, S., LAHLOU-KASSI, A., REGE, J.E.O., MUKASA-MUGERWA, E., ANINDO, D., SOVANI, S., BAKER, R.L. (1998): Breed and season effects on the peri-parturient rise in nematode egg output in indigenous ewes in a cool tropical environment. Vet. Parasitol., 77(2-3): 123–132. DOI: 10.1016/S0304-4017(97)00219-7TEMBELY S. LAHLOU-KASSI A. REGE J.E.O. MUKASA-MUGERWA E. ANINDO D. SOVANI S. BAKER R.L. 1998 Breed and season effects on the peri-parturient rise in nematode egg output in indigenous ewes in a cool tropical environment Vet. Parasitol 77 2-3 123 132 10.1016/S0304-4017(97)00219-7Open DOISearch in Google Scholar

THEODOROU, G., FRAGOU, S., CHRONOPOULOU, R., KOMINAKIS, A., ROGDAKIS, E., POLITIS, I. (2007): Study of immune parameters in three greek dairy sheep breeds during the periparturient period. J. Dairy Sci., 90(12): 5567–5571. DOI: 10.3168/jds.2007-0247THEODOROU G. FRAGOU S. CHRONOPOULOU R. KOMINAKIS A. ROGDAKIS E. POLITIS I. 2007 Study of immune parameters in three greek dairy sheep breeds during the periparturient period J. Dairy Sci 90 12 5567 5571 10.3168/jds.2007-0247Open DOISearch in Google Scholar

THOMAS, R., ALI, D. (1983): The effect of Haemonchus contortus infection on the pregnant and lactating ewes. Int. J. Parasitol., 13(4): 393–398THOMAS R. ALI D. 1983 The effect of Haemonchus contortus infection on the pregnant and lactating ewes Int. J. Parasitol 13 4 393 398Search in Google Scholar

TORRES-ACOSTA, F., RODRÍGUEZ-VIVAS, R. (1995): Efecto del parto sobre la eliminación de huevecillos de nemátodos y ooquistes de Eimeria en cabras criollas [The effect of parturition on nematode egg and oocyst output of Eimeria in criollo goats]. Rev. Biomedica, 6(4): 208–215 (In Spanish)TORRES-ACOSTA F. RODRÍGUEZ-VIVAS R. 1995 Efecto del parto sobre la eliminación de huevecillos de nemátodos y ooquistes de Eimeria en cabras criollas [The effect of parturition on nematode egg and oocyst output of Eimeria in criollo goats] Rev. Biomedica 6 4 208 215 (In Spanish)Search in Google Scholar

TORRES-ACOSTA, J., HOSTE, H. (2008): Alternative or improved methods to limit gastro-intestinal parasitism in grazing sheep and goats. Small Rumin. Res., 77: 159–173. DOI: 10.1016/j.smallrumres.2008.03.009TORRES-ACOSTA J. HOSTE H. 2008 Alternative or improved methods to limit gastro-intestinal parasitism in grazing sheep and goats Small Rumin. Res 77 159 173 10.1016/j.smallrumres.2008.03.009Open DOISearch in Google Scholar

TOSCAN, G., CAUDURO, G., TADINELLO, J.F., WEBER, A., HEINLOFT, H., MEDEIROS, M., SANGIONI, L.A., SILVEIRA, F. (2017): Immune response of sheep naturally infected with Haemonchus spp. on pastures with two different nutritional conditions. Semina: Ciênc. Agrárias, 38(2): 809–819. DOI: 10.5433/1679-0359.2017v38n2p809TOSCAN G. CAUDURO G. TADINELLO J.F. WEBER A. HEINLOFT H. MEDEIROS M. SANGIONI L.A. SILVEIRA F. 2017 Immune response of sheep naturally infected with Haemonchus spp on pastures with two different nutritional conditions. Semina: Ciênc. Agrárias 38 2 809 819 10.5433/1679-0359.2017v38n2p809Open DOISearch in Google Scholar

TRENTI, A., TEDESCO, S., BOSCARO, C., TREVISI, L., BOLEGO, C., CIGNARELLA, A. (2018): Estrogen, angiogenesis, immunity and cell metabolism: Solving the puzzle. Int. J. Mol. Sci., 19(3). DOI: 10.3390/ijms19030859TRENTI A. TEDESCO S. BOSCARO C. TREVISI L. BOLEGO C. CIGNARELLA A. 2018 Estrogen, angiogenesis, immunity and cell metabolism: Solving the puzzle Int. J. Mol. Sci 19 3 10.3390/ijms19030859Open DOISearch in Google Scholar

VALDERRÁBANO, J., GÓMEZ-RINCÓN, C., URIARTE, J. (2006): Effect of nutritional status and fat reserves on the periparturient immune response to Haemonchus contortus infection in sheep. Vet. Parasitol., 14: 122–131. DOI: 10.1016/j.vetpar.2006.04.029VALDERRÁBANO J. GÓMEZ-RINCÓN C. URIARTE J. 2006 Effect of nutritional status and fat reserves on the periparturient immune response to Haemonchus contortus infection in sheep Vet. Parasitol 14 122 131 10.1016/j.vetpar.2006.04.029Open DOISearch in Google Scholar

VAN GELDORP, P.J.A., VAN VEEN, T.S. (1976): Periparturient rise in faecal helminth egg counts of Udah sheep in the Zaria area of Nigeria. Vet. Parasitol., 1(3): 265–269. DOI: 10.1016/03044017(76)90099-6VAN GELDORP P.J.A. VAN VEEN T.S. 1976 Periparturient rise in faecal helminth egg counts of Udah sheep in the Zaria area of Nigeria Vet. Parasitol 1 3 265 269 10.1016/03044017(76)90099-6Open DOISearch in Google Scholar

VANDE, F., CHARLIER, J., CLAEREBOUT, E. (2018): Farmer behavior and gastrointestinal nematodes in ruminant livestock-uptake of sustainable control approaches. Frontiers Vet. Sci., 5. DOI: 10.3389/fvets.2018.00255VANDE F. CHARLIER J. CLAEREBOUT E. 2018 Farmer behavior and gastrointestinal nematodes in ruminant livestock-uptake of sustainable control approaches Frontiers Vet. Sci 5 10.3389/fvets.2018.00255Open DOISearch in Google Scholar

VANIMISETTI, H.B., ANDREW, S.L., ZAJAC, A.M., NOTTER, D.R. (2004): Inheritance of fecal egg count and packed cell volume and their relationship with production traits in sheep infected with Haemonchus contortus J. Anim. Sci., 82(6): 1602–1611. DOI: 10.2527/2004.8261602xVANIMISETTI H.B. ANDREW S.L. ZAJAC A.M. NOTTER D.R. 2004 Inheritance of fecal egg count and packed cell volume and their relationship with production traits in sheep infected with Haemonchus contortus J. Anim. Sci 82 6 1602 1611 10.2527/2004.8261602xOpen DOISearch in Google Scholar

VARGAS-DUARTE, J.J., LOZANO-MÁRQUEZ, H., GRAJALES-LOMBANA, H.A., MANRIQUE-PERDOMO, C., MARTÍNEZ-BELLO, D.A., SAEGERMAN, C., RAES, M., KIRSCHVINK, N. (2015): Effect of moxidectin treatment at peripartum on gastrointestinal parasite infections in ewes raised under tropical Andes high altitude conditions. Vet. Med. Int., 2015: 1–8. DOI: 10.1155/2015/932080VARGAS-DUARTE J.J. LOZANO-MÁRQUEZ H. GRAJALES-LOMBANA H.A. MANRIQUE-PERDOMO C. MARTÍNEZ-BELLO D.A. SAEGERMAN C. RAES M. KIRSCHVINK N. 2015 Effect of moxidectin treatment at peripartum on gastrointestinal parasite infections in ewes raised under tropical Andes high altitude conditions Vet. Med. Int 2015 1 8 10.1155/2015/932080Open DOISearch in Google Scholar

VÁZQUEZ-HERNÁNDEZ, M., GONZÁLEZ-GARDUÑO, R., TORRES-HERNÁNDEZ, G., MENDOZA DE GIVES, P., RUIZ-RODRÍGUEZ, J. (2006): Comparison of two grazing systems in the infestation with gastrointestinal nematodes of hair sheep. Vet. Mex., 37(1): 18–27VÁZQUEZ-HERNÁNDEZ M. GONZÁLEZ-GARDUÑO R. TORRES-HERNÁNDEZ G. MENDOZA DE GIVES P. RUIZ-RODRÍGUEZ J. 2006 Comparison of two grazing systems in the infestation with gastrointestinal nematodes of hair sheep Vet. Mex 37 1 18 27Search in Google Scholar

VINEER, H.R., BABER, P., WHITE, T., MORGAN, E.R. (2019): Reduced egg shedding in nematode-resistant ewes and projected epidemiological benefits under climate change. Int. J. Parasitol., 49(12): 901–910. DOI: 10.1016/j.ijpara.2019.06.008VINEER H.R. BABER P. WHITE T. MORGAN E.R. 2019 Reduced egg shedding in nematode-resistant ewes and projected epidemiological benefits under climate change Int. J. Parasitol 49 12 901 910 10.1016/j.ijpara.2019.06.008Open DOISearch in Google Scholar

WANYANGU, S.W., MUGAMBI, J.M., BAIN, R.K., DUNCAN, J.L., MURRAY, M., STEAR, M.J. (1997): Response to artificial and subsequent natural infection with Haemonchus contortus in Red Maasai and Dorper ewes. Vet. Parasitol., 69(3-4): 275–282. DOI: 10.1016/S0304-4017(96)01129-6WANYANGU S.W. MUGAMBI J.M. BAIN R.K. DUNCAN J.L. MURRAY M. STEAR M.J. 1997 Response to artificial and subsequent natural infection with Haemonchus contortus in Red Maasai and Dorper ewes Vet. Parasitol 69 3-4 275 282 10.1016/S0304-4017(96)01129-6Open DOISearch in Google Scholar

WERNE, S., PERLER, E., MAURER, V., PROBST, J.K., HOSTE, H., DREWEK, A., HECKENDORN, F. (2013): Effect of sainfoin (Onobrychis viciifolia) and faba bean (Vicia faba) on the periparturient rise in ewes infected with gastrointestinal nematodes. Small Rumin. Res., 113(2-3): 454–460. DOI: 10.1016/j.smallrumres.2013.03.022WERNE S. PERLER E. MAURER V. PROBST J.K. HOSTE H. DREWEK A. HECKENDORN F. 2013 Effect of sainfoin (Onobrychis viciifolia) and faba bean (Vicia faba) on the periparturient rise in ewes infected with gastrointestinal nematodes Small Rumin. Res 113 2-3 454 460 10.1016/j.smallrumres.2013.03.022Open DOISearch in Google Scholar

WESTERS, T., JONES-BITTON, A., MENZIES, P., VANLEEUWEN, J., POLJAK, Z., PEREGRINE, A.S. (2017): Comparison of targeted selective and whole flock treatment of periparturient ewes for controlling Haemonchus sp. on sheep farms in Ontario, Canada. Small Rumin. Res., 150: 102–110. DOI: 10.1016/j.smallrumres.2017.03.013WESTERS T. JONES-BITTON A. MENZIES P. VANLEEUWEN J. POLJAK Z. PEREGRINE A.S. 2017 Comparison of targeted selective and whole flock treatment of periparturient ewes for controlling Haemonchus sp on sheep farms in Ontario, Canada. Small Rumin. Res 150 102 110 10.1016/j.smallrumres.2017.03.013Open DOISearch in Google Scholar

WILKIE, H., XU, S., GOSSNER, A., HOPKINS, J. (2015): Variable exon usage of differentially-expressed genes associated with resistance of sheep to Teladorsagia circumcincta Vet. Parasitol., 212(3-4): 206–213. DOI: 10.1016/j.vetpar.2015.08.023WILKIE H. XU S. GOSSNER A. HOPKINS J. 2015 Variable exon usage of differentially-expressed genes associated with resistance of sheep to Teladorsagia circumcincta Vet. Parasitol 212 3-4 206 213 10.1016/j.vetpar.2015.08.023Open DOISearch in Google Scholar

WILLIAMS, A.R., GREEF, J.C., VERCOE, P.E., DOBSON, R.J., KARLSSON, L.J.E. (2010a): Merino ewes bred for parasite resistance reduce larval contamination onto pasture during the peri-parturient period. Animal, 4(1): 122–127. DOI: 10.1017/S1751731109990802WILLIAMS A.R. GREEF J.C. VERCOE P.E. DOBSON R.J. KARLSSON L.J.E. 2010a Merino ewes bred for parasite resistance reduce larval contamination onto pasture during the peri-parturient period Animal 4 1 122 127 10.1017/S1751731109990802Open DOISearch in Google Scholar

WILLIAMS, A.R., PALMER, D.G., WILLIAMS, I.H., VERCOE, P.E., EMERY, D.L., KARLSSON, L.J.E. (2010b): Relationships between immune indicators of parasitic gastroenteritis, nematode burdens and faecal dry matter in sheep. Anim. Prod. Sci., 50: 219–227. DOI: 10.1071/AN09144WILLIAMS A.R. PALMER D.G. WILLIAMS I.H. VERCOE P.E. EMERY D.L. KARLSSON L.J.E. 2010b Relationships between immune indicators of parasitic gastroenteritis, nematode burdens and faecal dry matter in sheep Anim. Prod. Sci 50 219 227 10.1071/AN09144Open DOISearch in Google Scholar

WOOLASTON, R.R. (1992): Selection of Merino sheep for increased and decreased resistance to Haemonchus contortus: peri-parturient effects on faecal egg counts. Int. J. Parasitol: Drugs and Drug Resist., 22(7): 947–953. DOI: 10.1016/0020-7519(92)90052-MWOOLASTON R.R. 1992 Selection of Merino sheep for increased and decreased resistance to Haemonchus contortus: peri-parturient effects on faecal egg counts Int. J. Parasitol: Drugs and Drug Resist 22 7 947 953 10.1016/0020-7519(92)90052-MOpen DOISearch in Google Scholar

XIE, H.L., STANKIEWICZ, M., HUNTLEY, J.F., SEDCOLE, J.R., MCANULTY, R.W., GREEN, R.S., SYKES, A.R. (2004): The effects of cold exposure, food allowance and litter size on immunity of periparturient sheep to Teladorsagia circumcincta and Trichostrongylus colubriformis Anim. Sci., 78(1): 149–158. DOI: 10.1017/s1357729800053935XIE H.L. STANKIEWICZ M. HUNTLEY J.F. SEDCOLE J.R. MCANULTY R.W. GREEN R.S. SYKES A.R. 2004 The effects of cold exposure, food allowance and litter size on immunity of periparturient sheep to Teladorsagia circumcincta and Trichostrongylus colubriformis Anim. Sci 78 1 149 158 10.1017/s1357729800053935Open DOISearch in Google Scholar

YAZWINSKI, T.A., GOODE, L., MONCOL, D.J., MORGAN, G.W., LINNERUD, A.C. (1981): Haemonchus contortus resistance in straightbred and crossbred Barbados Blackbelly sheep. J. Anim. Sci., 51(2): 279–284. DOI: 10.2527/jas1980.512279xYAZWINSKI T.A. GOODE L. MONCOL D.J. MORGAN G.W. LINNERUD A.C. 1981 Haemonchus contortus resistance in straightbred and crossbred Barbados Blackbelly sheep J. Anim. Sci 51 2 279 284 10.2527/jas1980.512279xOpen DOISearch in Google Scholar

ZARAGOZA-VERA, C.V., AGUILAR-CABALLERO, A.J., GONZÁLEZ-GARDUÑO, R., ARJONA-JIMÉNEZ, G., ZARAGOZA-VERA, M., TORRES-ACOSTA, J.F.J., MEDINA-REYNÉS, J.U., BERUMEN-ALATORRE, A.C. (2019): Variation in phenotypic resistance to gastrointestinal nematodes in hair sheep in the humid tropics of Mexico. Parasitol. Res., 118(2): 567–573. DOI: 10.1007/s00436-018-06201-wZARAGOZA-VERA C.V. AGUILAR-CABALLERO A.J. GONZÁLEZ-GARDUÑO R. ARJONA-JIMÉNEZ G. ZARAGOZA-VERA M. TORRES-ACOSTA J.F.J. MEDINA-REYNÉS J.U. BERUMEN-ALATORRE A.C. 2019 Variation in phenotypic resistance to gastrointestinal nematodes in hair sheep in the humid tropics of Mexico Parasitol. Res 118 2 567 573 10.1007/s00436-018-06201-wOpen DOISearch in Google Scholar

ZÁRATE FRUTOS, R., PEDROZO PRIETO, R., ACOSTA GONZÁLEZ, R., LARA NUÑEZ, M., BÁEZ ESCALANTE, M., GONZÁLEZ CASTRO, A. (2014): Estudio de perfiles metabólicos en ovinos de la raza Texel en los periodos preservicio, gestación y posparto [Metabolic profiles in Texel sheep in preservice, last third of gestation and early lactation periods]. Compendio Cienc. Vet., 4(2): 39–46. Available in: https://www.researchgate.net/publication/282253149%0AESTUDIO (In Spanish)ZÁRATE FRUTOS R. PEDROZO PRIETO R. ACOSTA GONZÁLEZ R. LARA NUÑEZ M. BÁEZ ESCALANTE M. GONZÁLEZ CASTRO A. 2014 Estudio de perfiles metabólicos en ovinos de la raza Texel en los periodos preservicio, gestación y posparto [Metabolic profiles in Texel sheep in preservice, last third of gestation and early lactation periods] Compendio Cienc. Vet 4 2 39 46 Available in https://www.researchgate.net/publication/282253149%0AESTUDIO (In Spanish)Search in Google Scholar

ZVINOROVA, P.I., HALIMANI, T.E., MUCHADEYI, F.C., MATIKA, O., RIGGIO, V., DZAMA, K. (2016): Breeding for resistance to gastrointestinal nematodes - the potential in low-input/output small ruminant production systems. Vet. Parasitol., 225: 19–28. DOI: 10.1016/j.vetpar.2016.05.015ZVINOROVA P.I. HALIMANI T.E. MUCHADEYI F.C. MATIKA O. RIGGIO V. DZAMA K. 2016 Breeding for resistance to gastrointestinal nematodes - the potential in low-input/output small ruminant production systems Vet. Parasitol 225 19 28 10.1016/j.vetpar.2016.05.015Open DOISearch in Google Scholar

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