Improving beef quality through rumen microbial modulation by varying alfalfa hay proportions in the diet

This study evaluated the effects of different dietary proportions of alfalfa hay on growth performance, carcass characteristics, meat quality, rumen fermentation, and rumen microbiota in beef cattle.

Sixty Simmental crossbred cattle were randomly assigned to diets containing 11.57% (low alfalfa hay group, LAG), 20.83% (medium alfalfa hay group, MAG), or 30.09% (high alfalfa hay group, HAG) alfalfa hay, with four replicates per treatment and five cattle per replicate.

The LAG diet significantly increased final body weight and reduced beef shear force. The LAG diet also resulted in the highest saturated fatty acid content in the longissimus thoracis muscle. Based on 16S rRNA analysis, the LAG group had significantly higher relative abundances of Eubacterium_brachy_group and norank_f_Eubacterium_coprostanoligenes_group. Muscle n-6 polyunsaturated fatty acid content was positively correlated with the relative abundance of Christensenellaceae_R-7_group, whereas Succiniclasticum abundance was negatively correlated with the PICRUSt2-predicted acarbose and validamycin biosynthesis pathway.

A dietary alfalfa hay proportion of 11.57% improved final body weight and beef tenderness and was associated with distinct changes in rumen microbial composition and predicted microbial functions. These findings provide a scientific basis for using alfalfa hay to produce high-quality beef.