Forage growth, yield, and quality responses of two hybrids of Napier and sorghum at three cutting intervals in the southern province of Sri Lanka

A 3 × 3 factorial study was conducted in the southern province of Sri Lanka to compare two cultivars of Napier hybrid grass, CO-3 and CO-4, and fodder sorghum (var. sugar graze) at three cutting intervals (4, 6, and 8 weeks) during a 2-year period. For cultivars, plant height followed the order sugar graze > CO-4 > CO-3, while the stem diameter was greater for CO-3, followed by CO-4 and sugar graze. Number of leaves was always greater in hybrid Napier compared with sugar graze. Cultivar had a significant effect on annual dry matter (ADM) production (CO-3 > CO-4 > sugar graze) during both years. Sugar graze had a higher crude protein (CP) and a lower crude fiber (CF) concentration compared to CO-3 or CO-4. Cutting interval also had a significant effect on ADM production and CF concentration, with higher values obtained in the following order: 8 weeks > 6 weeks > 4 weeks. The results revealed that cultivars CO-3 and CO-4 were superior in overall DM and CP yields while Sugar graze performed equally well with highest CP and lowest CF concentrations while cutting interval of 8 weeks appears optimal for the environmental conditions in the area.