Livestock-Based Farming Systems, Renewable Resources and the Environment
The aim of this study was to evaluate the digestibility and growth of cattle with or without bypass protein supply and in faunated and defaunated state. This study also exploited the real-time PCR technique in understanding the shift or fold changes of rumen cellulolytic bacteria (Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens) and methanogenic archaea under different feeding conditions. Twelve crossbred Sindhi cattle weighing from 140 to 160 kg were arranged in a two by two factorial design (absence and presence of protozoa by soybean drench; with or without cottonseed supplement). The experiment lasted for 90 days. It was found that there was a trend of increased feed intake in defaunated cattle at both supplemental regimes but the difference did not reach a significant level of 0.05. In addition, cattle supplemented with cottonseed cake were not affected by oil drench treatment (P > 0.05) but there was an improvement in cattle received cottonseed cake with higher digestibility of DM and CP in the defaunated group. As a result, a single dose of oil drench improved daily gain up 17.2% (0.667 vs. 0.495 kg/head) in defaunated and faunated cattle, respectively. Preliminary results of real-time PCR indicated that defaunation did not have significant effects on the number of methanogenic archaea in the rumen of cattle; However, further analysis is undertaken to figure out relative changes of these bacteria and also cellulolytic bacteria before any conclusion can be drawn.