Influence of nitrogen fertilization and stage of maturity of mottgrass ( Pennisetum purpureum) on its composition, dry matter intake, ruminal characteristics and digestion kinetics in cannulated buffalo bulls

Abstract

Four ruminally cannulated buffalo bulls (300 kg) were fed mottgrass diets using a 4 × 4 Latin-square design. Treatments consisted of mottgrass fertilized with 0 or 110.4 kg N/ha and harvested at 40 (ECM) and 60 (LCM) days. Fertilization increased the concentrations of crude protein (CP) and fibre contents. The CP contents of the mottgrass decreased and fibre contents increased with advancing maturity. Intake of dry matter (DM), organic matter (OM), CP, neutral detergent fibre (NDF) and acid detergent fibre (ADF) were higher in buffalo bulls fed ECM than those fed LCM. The concentrations of total ruminal volatile fatty acids (VFA) and acetate were higher in animals fed ECM than those fed LCM. In situ DM and NDF digestibilities of ECM were higher than those of LCM. However, DM and NDF digestibilities of ECM remained unaltered by N fertilization. The rates of DM and NDF disappearance of ECM were faster than those of LCM. However, N fertilization did not affect the DM and NDF rates of disappearance. In situ lag time of DM and NDF digestion were shorter for ECM than those for LCM but no effect was noted due to N fertilization. The digestion extent of DM and NDF at 96 h was affected by maturity. However, N fertilization did not have any effect. The digestibilities of DM, OM, CP, NDF and ADF were higher in buffalo bulls fed ECM than those fed LCM. However, the N fertilizer did not affect digestibilities of these nutrients. In conclusion, the N fertilization increased the CP concentration of the mottgrass but could not reverse the ill effect of maturity on the quality of mottgrass.