The developmental trajectory and maturation of the Hulunbuir sheep (Ovis aries) microbiome

The rumen microbiota plays a pivotal role in the growth performance of host animals, primarily due to its ability to ferment ingested feed. Hulunbuir sheep exhibited a slow growth rate compared to other local breeds. A deeper comprehension of the development of the rumen bacteria community in Hulunbuir sheep can offer insights into the factors contributing to their slow growth rate. This study utilized metagenomic analysis of rumen content samples from Hulunbuir sheep to investigate the patterns of microbial growth and their relationship with the ADG. The results of the PCoA and enterotype analyses demonstrated that the ruminal bacterial community developed distinct characteristics following weaning. The dominant bacterial phyla in the rumen of Hulunbuir sheep, Bacteroidetes and Firmicutes, exhibited a significant age-related change. At the genus level, while the abundance of dominant bacterial genera changed with the growth of Hulunbuir sheep, Prevotella consistently maintained a high abundance across all age time points. We then examined the effects of age on microbial function by analyzing carbohydrate-metabolizing enzymes and protein-metabolizing peptidases. The abundance of carbohydrate-metabolizing enzymes decreased with growth, while peptidases showed opposite dynamics. Under the current feeding conditions correlation analysis showed that the abundances of Firm-04, CAG-83, and GCA-900,199,385 were negatively correlated with ADG (R<-0.4, p < 0.05), while the abundance of Ga6A1 was positively correlated with ADG (R > 0.5, p < 0.05). In addition, we found 67 MAGs related to ADG, which are capable of secreting carbohydrates-metabolizing enzymes and peptidase. This study uncovers the temporal dynamics of rumen microbiota development during the early to late fattening phase and identifies microbes associated with ADG, which could inform strategies to improve growth and production efficiency.