Effect of feeding Acacia nilotica pods to sheep on nutrient digestibility, nitrogen balance, ruminal protozoa and rumen enzymes activity

This study was conducted to evaluate the effect of supplying two levels of Acacia nilotica (A.nilotica) pods to rations of sheep on nutrient digestibility, nitrogen balance and rumen liquor parameters (pH, total protozoa count, protein concentration and enzymes activity). Twelve mature rams (50 +/- 1.25 kg B.W.) were distributed into three groups, each with four rams. Animals in group one were considered as a control which fed a basal diet, consisting of concentrate mixture and Egyptian clover. The second group and the third one received the same basal diet with supplying the concentrate mixture by 1.5% and 3.0% of A.nilotica pods meal respectively. The experiment lasted for 3 weeks. It was found that supplementation of A.nilotica pods to the concentrate mixture at a rate of 1.5% and 3.0% significantly improved the total feed intake compared to the control. The digestibility of dry matter and crude fibre was significantly reduced with A.nilotica supplements, whereas the digestibility of crude protein was significantly improved. All of nitrogen intake and N-retained were significantly increased in rams fed on concentrates with 1.5% and 3.0% A. nilotica pods when compared to the control. The pH of ruminal fluid was not affected by the dietary treatments. Nevertheless, the total rumen protozoa count was significantly decreased in A.nilotica pods supplemented groups. Also, the rumen protein concentration and the ruminal enzymes activity, especially alpha-amylase, cellulase and protease, were lower in A.nilotica pods supplemented treatments. In conclusions, inclusion of low levels of A.nilotica pods (1.5% and 3.0%) in the concentrates can be used as a natural protein protectant in ruminants by forming tannin protein complexes in the rumen to maximize the amino acids available in the lower digestive tract. Also, these levels can increase the protein digestibility as well as the N-retained in the body .