Nutrient digestibility, nitrogen balance and rumen metabolites of finishing bunaji bulls fed diets containing graded levels of palm kernel cake

The efficiency of nitrogen by ruminants is often very low when feed provision is made under feedlot system of management. Against this  background, a study was carried out to evaluate the nutrient digestibility, nitrogen balance and rumen metabolites in finishing Bunaji Bulls fed diets containing graded levels of palm kernel cake. A total of 20 Bunaji bulls with a live weight range of 190-200kg and aged 2- 2.5 years were balanced for  weight and allotted to five  ietary treatments. They were individually penned and fed diets containing (10, 20, 30 and 40%) of Palm Kernel Cake (PKC) and Digitaria smutsii hay each at 2% of their body weight each. At the end of the feeding trials, rumen fluid was collected at 0, 3, 6 and 9hrintervals to determine the pH, rumen ammonia nitrogen and rumen total volatile fatty acid. During metabolism trials, the bulls were allowed 14 days adjustment period and 7 days for feacal and urine collection. The Crude Protein (CP) and Metabolizable Energy (ME) of the fattening diets varied between 15.63 and 20.31% and 11.75 to 11.78MJ/kg DM respectively, while the Crude Fibre (CF) varied from 13.92 to 23.31%. There was no significant (P>0.05) difference in the Dry Matter, Neutral Detergent Fibre (NDF) and Acid Detergent Fibre (ADF) digestibility for all the fattened Bunaji bulls but those on 20% and 30% PKC inclusions have the higher CP digestibility values than others. The least CP digestibility value was obtained for Bulls on control diet. All the fattening bulls had positive nitrogen balance irrespective of the level of PKC in their diet. The Total Volatile  Fatty Acid (TVFA)  as highest at 9hr post feeding (28.19) but differed at 0hr (23.80), 3hr (24.15) and 6hr (25.80) which were similar (P>0.05) while the Rumen Ammonia Nitrogen (RAN) at 3hr and 9hr post feeding were largely similar. The supplied nutrients were well tolerated, properly utilized with positive nitrogen balance and adequate rumen metabolite and optimum performance is with 30% inclusion. PKC can be included in fattening diets  without any adverse effect on nutrient utilization, nitrogen balance and rumen metabolite. Keywords: finishing Bunaji bull, nutrient digestibility, nitrogen balance, palm kernel cake and rumen metabolit