Comparative analysis of rumen fermentation parameters and bacterial profiles during adaption to different fattening stages in beef cattle fed TMR with various forage silage

Abstract

We investigated the long-term effects of total mixed rations (TMR) containing various forage silages on the rumen community structure in beef cattle. Fifteen Simmental bulls (437.73 ± 4.01 kg) were fattened for 180 d, split into three trial stages (P1: 1–60 d, P2: 61–120 d, P3: 121–180 d). The diets were composed of corn silage, oat silage, alfalfa silage, wheat straw, and concentrates, formulated into a TMR. Rumen fluid was collected separately on the 60th, 120th, and 180th days among the three fattening stages. High-throughput 16S rRNA gene sequencing was used to analyse rumen bacterial composition and function, and the correlation between rumen bacteria and fermentation parameters was determined using redundant analysis. The results showed that rumen fermentation parameters were stable during long-term fattening. The alpha diversity index indicated that bacterial diversity was higher during the late fattening phase than in the early phase. The most abundant bacteria were Bacteroidetes, Firmicutes, and Prevotella_1 at the three fattening stages. The bacterial communities were clearly separated in the different stages, as indicated by the Box diagram. The thirteen bacterial taxa identified by LEfSe were significantly enriched in the rumen during the three stages. KEGG pathway fractions indicated that carbohydrate metabolism, amino acid metabolism, and energy metabolism pathways were enriched in the rumen during the three stages. In conclusion, we found that long-term feeding of beef cattle with high-quality forage + low levels of concentrate was a healthy and efficient feeding method, promoting a healthy and suitable long-term change in the rumen microbial environment.