Evaluate feeding effects of pelletized total mixed ration on Hu sheep: growth, rumen fermentation, and rumen bacterial community.

Objective: The study aimed to compare the growth performance, rumen fermentation and rumen bacterial community of fattening Hu sheep fed either total mixed ration (TMR) or pelleted total mixed ration (PTMR), and to assess the feeding efficiency.

Methods: In a 58-day feeding experiment, forty-eight Hu sheep were randomly assigned to two groups (TMR and PTMR), with six pens per group and four sheep per pen. Body weight and feed intake were measured throughout the experiment to assess growth performance. On the final day of the experiment, rumen fluid was collected from sheep using a rumen fluid collector two hours post-feeding.

Results: The sheep in the PTMR group exhibited significantly higher body weight (p<0.05), average daily gain (p<0.01), and dry matter intake (p<0.05) compared to those in the TMR group. No statistically significant differences were observed in rumen fermentation parameters between the TMR and PTMR groups. However, analysis of rumen bacteria revealed that the Sob, Ace, Bootstrap, Shannon, and Chao indices were significantly lower in the PTMR group compared to TMR group (p<0.05). Bacteroidetes and Firmicutes were the predominant bacteria in all groups, with the abundance of Succinivibrionaceae_UCG-001 was significantly lower in the PTMR group. The relative abundance of Rikenellaceae_RC9_gut_group, NK4A214_group, and Streptococcus, was significantly higher in the TMR group than in the PTMR group (p<0.05). Bacterial function prediction showed downregulation of energy production and conversion pathway in the PTMR group (p<0.05). Correlation analysis indicated that norank_f_Bacteroidales_RF16 positively correlated with butyric acid (p<0.05), while Anaerovibrio negatively correlated with acetic, propionic acids, butyric acid, and total volatile fatty acids (p<0.05).

Conclusion: In summary, this study demonstrated that PTMR, while reducing rumen bacterial abundance in Hu sheep, significantly increased their average daily gain and dry matter intake, indicating its potential for practical application.