Influence of Dietary Chitosan Supplementation on Growth Indicators, Nutrient Digestibility, Immunity, Cecal Microbiota, and Intestinal Morphology of Growing Male Rabbits

The present study aimed to assess the influence of dietary chitosan on production performance, nutrient digestibility, slaughter traits, immune function, cecal microbiota, and intestinal histomorphometry of growing rabbits for 56 days. In total, sixty New Zealand White male rabbits aged 35 days (574±7.26 g, mean ± SEM) were arbitrarily assigned to four dietary groups. The experimental diets were fortified with chitosan powder at 0, 250, 500, and 1000 mg per kg diet, respectively. It was found that final weight, specific growth rate, daily weight gain, and feed: gain enhanced linearly (P<0.05) with increasing chitosan levels in the diet. No significant differences were found for all slaughter traits, including hot carcass weight, carcass yield, and internal organ weights, besides carcass parts, including head, fore, intermediate and hind parts. Hematocrit percentage (linear, P = 0.024), serum lysozyme activity (linear, P = 0.004), immunoglobulin M, and complement C3 concentrations (linearly, P<0.001) increased with increasing chitosan supplementation levels. The organic matter (P = 0.009), dry matter (P = 0.008), and nitrogen-free extract (P = 0.012) digestibilities were enhanced quadratically by dietary supplementation with chitosan. Cecal lactobacilli, E. coli, coliform and Salmonella spp. populations (linear, P<0.05) decreased in response to chitosan supplementation. All the dietary chitosan levels increased villus width, villus length, and crypt depth (linear, P<0.001), whereas muscular layer thickness decreased (linear, P=0.002). In summary, supplementing the diet of growing rabbits with chitosan can improve growth indicators, immunity, nutrient digestibility, and intestinal morphology, as well as reduce pathogenic cecal bacteria.