Impact of probiotic blend on rumen fermentation, nutrient digestibility, and blood biochemistry in sheep

The significant contribution of ruminants to methane emissions has received considerable global attention in recent years. While dietary strategies have been implemented to mitigate this issue, probiotics have increasingly attracted research interest due to their potential as sustainable, effective, and eco-friendly solutions. Hence, the current study examines the potential of a proprietary probiotic blend (ABLB), both alone and in combination with Saccharomyces cerevisiae (SC), on rumen characteristics, nutrient digestibility, and blood biochemical parameters in sheep. Animals were fed a basal diet or supplemented daily with 1 g/animal of a probiotics blend containing Lactobacillus acidophilus, Lactobacillus bulgaricus, Bacillus licheniformis, and Bifidobacterium bifidum (1:1:1:1) at two concentrations: 2 × 10⁹ CFU/g (ABLB2) and 4 × 10⁹ CFU/g (ABLB4), representing the 2^nd and 3^rd dietary treatments, respectively. The 4^th (ABLB2+SC) and 5^th (ABLB4+SC) dietary treatments consisted of the bacterial blend at the same two concentrations combined with SC (1 g/animal/day). Probiotic supplementation significantly (P < 0.05) decreased ruminal ammonia-nitrogen (NH₃-N) concentrations and pH, while significantly (P < 0.05) increasing total volatile fatty acid (TVFA) concentration, microbial crude protein (MCP) production, and protozoal counts, with the most pronounced effects observed in the ABLB2+SC group. Compared to the control group, significant improvements (P < 0.05) were observed with ABLB2+SC in the digestibility of dry matter (DM), crude fiber (CF), crude protein (CP), and ether extract (EE), as well as in the total digestible nutrients (TDN), starch value (SV), and digestible crude protein (DCP) (%) values of the tested diets. Additionally, all probiotic supplements significantly increased serum protein and glucose concentrations, while significantly decreasing serum urea, creatinine, aspartate aminotransferase (AST), triglycerides, and cholesterol compared with the basal diet (P < 0.05). This study underscores the potential of a blended probiotic supplementation in sheep nutrition to enhance rumen function, improve blood health, and optimize nutrient utilization.