Dietary Supplementation with Multispecies Probiotic Fermented Broth Improves Nutrient Digestibility and Carcass Traits While Modulating the Cecal Microbiota and Thigh Muscle Fatty Acid Profile in Yellow-Feathered Broilers.

This study evaluated the effects of dietary supplementation with 4% multispecies probiotic fermented broth (MPFB) on the apparent nutrient digestibility, carcass traits, serum immune indices, intestinal morphology, cecal microbiota, and thigh muscle nutrient composition in 815-strain yellow-feathered broilers. A total of 400 healthy 4-day-old broilers with similar body weight and a 1:1 sex ratio were randomly assigned to the control group with basal diet (CON) or the MPFB group with 4% MPFB. The results showed that MPFB significantly increased the apparent digestibility of crude protein and calcium (p < 0.05), and that of crude fiber and phosphorus (p < 0.01). The MPFB group had a higher thigh muscle yield and a lower abdominal fat yield (p < 0.05), while carcass yield tended to increase (p = 0.071). MPFB also elevated serum immunoglobulin M and interleukin-2 concentrations (p < 0.05), increased duodenal villus height (p < 0.05), reduced duodenal crypt depth (p < 0.05), and increased the villus height to crypt depth ratio in the duodenum, jejunum, and ileum (p < 0.05). Cecal microbiota analysis showed that MPFB significantly enriched Ruminococcus gauvreauii_group, Ruminococcus torques_group, and Turicibacter (p < 0.05), while Bacteroides tended to increase (p = 0.093), which were positively correlated with the improved nutrient digestibility and duodenal morphology. In thigh muscle, MPFB tended to increase cysteine content (p = 0.081), decreased C14:0 (p < 0.05), C16:0 and total saturated fatty acids (p < 0.01), increased C20:2 (p < 0.05), and tended to decrease C12:0 and C16:1 but increase C18:2n6c and total polyunsaturated fatty acid (p < 0.10). In conclusion, dietary supplementation with 4% MPFB improved nutrient utilization and selected carcass traits and modulated the thigh muscle fatty acid profile in yellow-feathered broilers, which are potentially associated with improved intestinal morphology and modulation of the cecal microbiota.