Effect of synchronization of ruminal energy and nitrogen supply on in vitro microbial protein synthesis and rumen fermentation*

Present study was conducted to evaluate the effect of synchronization of ruminal energy and nitrogen (N) supply on in vitro microbial protein synthesis (MPS) and rumen fermentation pattern. Commonly used tropical feeds and fodders(sorghum grain, maize grain, wheat bran, mustard cake, groundnut cake, maize fodder, oat fodder and wheat straw) were first evaluated in sacco for their organic matter and N degradation characteristics. The protein sources (mustard and groundnut-cake) had faster N degradation rate while energy source (sorghum grain) had faster whereas the other (maize grain) had slower rate of energy release. By varying the proportion of feed ingredients, 6 isonitrogenous and isocaloric diets were formulated and their synchrony index (SI) was calculated using in sacco degradability kinetic data. The diets were classified as high(HS), medium (MS) and low(LS) synchronous based on their SI with 2 diets in each category. These diets were evaluated for rumen fermentation parameters by in vitro gas production technique. The total gas production from HS and MS diets was significantly higher indicating higher fermentation while any specific trend in methane production was not observed. Degradability of HS and MS diets was significantly higher than that of LS diets. The NH3-N content in HS and MS diets was significantly lower indicating higher uptake of N from these diets while TCA-ppt N and total N content was significantly higher from these diets in comparison with LS diets. The TVFA and propionate production was higher in HS and MS diets while acetate production was higher in LS diets. Acetate: propionate ratio was significantly lower in HS and LS diets. The HS and MS diets produced significantly higher amount of microbial N with greater efficiency of MPS. It was concluded that due to synchronization of energy and N supply, the in vitro rumen fermentation was improved with higher MPS and efficiency of N capture.