Evaluation of sorghum stover based complete rations with different roughage to concentrate ratio for efficient microbial biomass production by using In vitro gas production technique

An in vitro study was conducted to evaluate the optimum roughage to concentrate ratio in complete rations using sorghum stover (SS) as a roughage source since it is a main feed resource for urban and peri-urban dairies. Eight complete rations were prepared with roughage (R) to concentrate (C) ratio of 100R:0C to 30R:70C. In vitro gas production (ml) at 24 h incubation, in vitro organic matter digestibility and metabolizable energy, truly digestible organic matter and ammonia nitrogen production were increased linearly (P<0.01) as the proportion of concentrate was increased in the ration. Significantly higher (P<0.01) total volatile fatty acid concentration was observed in 50R:50C, 40R:60C and 30R:70C compared to other rations. Significantly (P<0.01) highest partitioning factor, microbial biomass production and efficiency of microbial biomass production were recorded at 60R:40C ratio followed by 50R:50C. Therefore, the present study suggested that SS can be included in complete rations for ruminants at the level of 60 per cent for economic milk and meat production.