Effect of Roughage to Concentrate Ratio in the Diet on the Rumen Environment and Nutrient Utilization in Goat and Sheep

The study was undertaken to assess the effect of low roughage-high concentrate (LR-HC in 30:70 ratio) diet and high roughage-low concentrate (HR-LC in 70:30 ratio) diet on the rumen fermentation pattern and nutrient utilization in small ruminants. The net gas production (P<0.01), digestibility of NDF and true OM (P<0.05) and ME availability (P<0.01) were higher, while the methane production (ml/g digestible OM) was lower (P<0.01) in LR-HC diet as compared to HR-LC diet. The number of holotrichs, entodinium, total protozoa and bacteria was higher (P<0.01), while that of anaerobic fungi was lower (P<0.01) in the rumen of animals fed LR-HC diet as compared to HR-LC diet. The protozoal number was numerically higher (P>0.05) at 4h post feeding as compared to before feeding, while reverse trend (P<0.05) was observed in case of bacteria and fungi. The number of anaerobic bacteria and fungi was higher (P<0.01) in ram as compared to bucks. The total-N, TCA precipitable-N and NPN concentration was higher (P<0.01) in animals fed LR-HC diet as compared to HR-LC diet. All the nitrogen fractions in the SRL were higher (P<0.01) in bucks as compared to rams. The lactic acid, total volatile fatty acids (VFAs) and individual VFAs production, except that of iso-butyrate was higher (P<0.01) in LR-HC diet as compared to HR-LC diet. However, the relative proportion of acetate, iso-butyrate and isovalerate was higher (P<0.05), while that of propionate and valerate was lower (P<0.05) in HR-LC diet as compared to LR-HC diet. The daily DM intake, digestibility of DM, OM and hemicellulose; daily N-intake,urinary-N excretion was higher (P<0.01) in LR-HC diet as compared to HR-LC diet. The N-retention was comparable in LR-HC and HR-LC diet. It was concluded that the roughage level in the diet of sheep and goat affected the rumen microbial population, which in turn influenced the rumen fermentation pattern and nutrient utilization.