Objective: This study was conducted to evaluate the effects of supplementation strategies containing rumen-protected glucose (RPG) on growth performance, colonic fermentation characteristics, bacterial community structure, carcass traits, and meat quality in Simmental beef cattle. Methods: Thirty Simmental bulls with an initial body weight of 578.4±14.7 kg were randomly assigned to 3 dietary treatments for 90 d, with 10 animals per treatment. All animals received the same basal total mixed ration (TMR), to which the treatment supplements were added. The treatments were CON, unprotected glucose (150 g/d) plus coating fat (150 g/d); T1, RPG (100 g/d) plus unprotected glucose (100 g/d) and coating fat (100 g/d); and T2, RPG (300 g/d). Growth performance was recorded throughout the trial. At the end of the experiment, colonic digesta were collected for fermentation and bacterial community analyses, and carcass traits and meat quality were evaluated after slaughter. Results: Compared with CON, both T1 and T2 had greater overall average daily gain (p<0.05), whereas feed efficiency differed marginally among treatments during the overall period (p = 0.049). In colonic digesta, propionate concentrations were higher in T1 and T2 than in CON, and butyrate concentration was higher in T2 than in CON and T1 (p<0.05). Alpha diversity was not affected by treatment; however, unweighted UniFrac-based PCoA showed differences in the overall colonic bacterial community structure among treatments.At the phylum and genus levels, several taxa showed nominal differences based on raw p values, but these were not retained after false discovery rate correction. Hot carcass weight and meat weight were greater in T1 and T2 than in CON (p<0.05). Intramuscular fat content was higher in T2 than in CON (p<0.05), whereas most other meat quality traits were not significantly affected. Conclusion: The supplementation strategies containing RPG improved overall growth performance and carcass output in Simmental beef cattle. They were also associated with higher colonic propionate and butyrate concentrations, indicating altered hindgut fermentation. The higher-RPG strategy (T2) was associated with greater intramuscular fat content.
Liu et al. (Mon,) studied this question.