Effects of Bacillus subtilis and Rhodotorula Yeast Culture on the Growth Performance, Meat Quality, Antioxidant Capacity, and Serum Metabolites in Yellow-Feathered Broilers

This study aimed to investigate the effects of dietary supplementation with <i>Bacillus subtilis</i> (BS) and <i>Rhodotorula</i> yeast culture (RYC) used as feed additives to study their effects on growth performance, meat quality, antioxidant capacity, and serum metabolomics in yellow-feathered broilers. A total of 192 one-day-old healthy yellow-feathered broilers were randomly divided into four treatment groups. The CON group was fed a basal diet, whereas the BS, RYC, and MIX groups were fed diets supplemented with 5 × 10⁹ CFU/kg BS, 5000 mg/kg RYC, and a combination of both, respectively. The experimental period comprised 56 days. In the initial stage of growth, compared with the CON group, the body weight and average daily gain of broilers in the BS group were significantly increased (<i>p</i> < 0.05). The BS group increased the activity of CAT and SOD in broilers at 28 days, and the activity of CAT in RYC and MIX group were also significantly increased (<i>p</i> < 0.05). BS could increase GSH-Px activity significantly in broilers at 56 days (<i>p</i> < 0.05). Moreover, in comparison with the CON group, the MIX group decreased shear force and drip loss significantly (<i>p</i> < 0.05). Serum metabolome analysis showed that the addition of BS or RYC alone had the greatest difference in the abundance of D-amino acid metabolism and lysine metabolism, while the combined addition of BS and RYC found that glycerophospholipid metabolism and tryptophan metabolism had the greatest difference. In conclusion, dietary addition of BS and RYC could improve the meat quality of yellow-feathered broilers.