Effects of combined <i>Bacillus coagulans</i> and yeast fermentation culture on growth performance, plasma biochemical indices, intestinal morphology, and microbial of broilers

The favorable impacts of Bacillus coagulans or yeast culture on broiler production performance and immune function have been acknowledged. However, the effects of the combined them (BcYc) on the broilers remained unknown. Thus, the current research aimed to assess the effects of BcYc (at dosages of 0, 200, 300, and 400 mg/kg) on growth performance, plasma biochemical indices, antioxidant capacity, and intestinal morphology and microbial composition in broilers. The results revealed that 1) broilers receiving 300 and 400 mg/kg of BcYc showed significantly higher body weights than the control group at 4 d and 21 d (P < 0.05). Additionally, when contrasted with the control group, the feed conversion ratio was significantly decreased in 300 mg/kg group during 4 to 21 d and in 400 mg/kg group during 4 to 42 d (P < 0.05). 2) At 21 d, the broilers supplemented with 300 and 400 mg/kg of BcYc demonstrated significantly elevated levels of albumin (ALB), glutathione peroxidase activity (GSH-Px), total antioxidant capacity, and catalase activity than the group that not supplemented with BcYc (P < 0.05). At 42 d, 400 mg/kg group showed significantly higher ALB and total protein and lower glutamic-pyruvic transaminase activity and malondialdehyde content in contrast to the control group (P < 0.05). Furthermore, at 42 d, GSH-Px activity in all experimental groups showed significantly higher compared to the control group (P < 0.05). 3) Nevertheless, no significant variation was observed neither in the jejunum or duodenum morphology among all groups (P > 0.05). 4) Adding 400 mg/kg of BcYc led to a significantly higher Sobs index and a lower Simpson index (P < 0.05), and an extremely significantly raised in Shannon index (P < 0.01), while adding 300 mg/kg of BcYc led to a significantly enhanced in Shannon index (P < 0.05). Additionally, supplementary BcYc significantly elevated the abundance of Firmicutes at the phylum level and Clostridia, Ruminococcus, Rikenella, Butyricicoccus, and Eubacterium in the genus level (P < 0.05). To sum up, supplementing BcYc at dosages of 400 mg/kg to yellow-feathered broilers diet can help improve growth performance, regulate plasma biochemical indicators, increase antioxidant capacity, and improve gut community composition.