Nutrient Utilization in Bulls Fed Fermented Rations Containing Palm Decanter Cake and Bacillus subtilis

Palm decanter cake (PDC) is an agro-industrial by-product with potential as an alternative feed resource for ruminants, although its relatively high fiber content may limit nutrient utilization. Incorporating PDC with probiotic Bacillus subtilis (PB) in fermented total mixed rations (FTMR) may provide a practical strategy for utilizing this by-product in beef cattle diets. This study evaluated animal responses to FTMR dietary regimens containing PDC and PB, with emphasis on feed intake, nutrient digestibility, rumen fermentation, microbial populations, and serum metabolites in beef cattle. Five Angus-crossbred bulls (initial body weight 477 ± 44 kg) were assigned to a 5 × 5 Latin square design. Dietary treatments consisted of a control FTMR without PDC or PB and four FTMR diets containing 10% or 20% PDC on a DM basis, supplemented with either 0.05% or 0.10% probiotic B. subtilis. Feed intake, apparent nutrient digestibility, rumen fermentation characteristics, microbial populations, and serum metabolites were determined. Dietary treatments did not affect dry matter intake, ruminal pH, NH3-N concentration, total volatile fatty acids, microbial populations, or serum metabolites (p>0.05). Ether extract intake differed among dietary regimens (p