Particulate Rate of Passage and Faeces Quality of Water Buffalo Fed Diets Varying in Concentrations of Nitrogen and Structural and Non-structural Carbohydrates

Effects of diet concentrations of carbon (C), nitrogen (N), neutral detergent fibre (NDF) and soluble carbohydrates (SC) on digesta passage and faeces quality were studied in water buffalo. Rhodes grass hay, soybean meal, wheat bran and maize were combined for a high C/N - high NDF/SC ratio (HH), low C/N - low NDF/SC ratio (LL), high C/N - low NDF/SC ratio (HL) and low C/N - high NDF/SC (LH) ratio. Diets were offered to four heifers each during 21 days adaptation and 7 days experimentation. When the experiment started animals received a pulse dose of ytterbium-marked fibre; particle passage was derived from a one-compartment age-dependent Gamma-2 model. Diet N concentration significantly affected faecal concentration of N (r= 0.82, P<0.001), NDF (r=0.50, P<0.05) and faecal NDF/N and C/N ratio (r≥ 0.83, P<0.001). Ruminal particle passage (λ) ranged from 0.033 h⁻¹ (HL) to 0.043 h⁻¹ (LL), and was significantly related to the N (r=-0.84, P<0.001) and C (r=-0.57, P<0.05) concentration of the diet. Total tract retention time was shortest (P<0.001) for diet LL. The results indicate that differences in diet quality entail significant quality differences in buffalo dung that are not annihilated by the species’ very efficient digestion of fibrous feeds.