Analysis of rumen fermentation, bacterial diversity and blood biochemical parameters in sheep fed with cotton straw and different roughage combinations

Cotton straw is highly lignified and poorly utilized as roughage, but a combination diet of a variety of feeds can increase the intake and nutrient utilization. This study focused on sheep (rams), and growth performance, rumen bacterial diversity, rumen fermentation and blood biochemical indices were determined after a 40-day trial. Different groups received different combinations of roughage, including alfalfa hay (AH), maize straw (MS) and cotton straw (CS). The CS+MS+AH (CMA) groups showed the highest positive associative effects and the best growth performance compared to other CS-containing diets. Fermentation parameters showed higher (p < 0.05) butyric, acetic, propionic and total volatile fatty acid content in the CMA group. In terms of blood biochemical parameters, except for alanine aminotransferase, which was significantly higher in CMA, no significant difference was seen between the groups for the other parameters (p > 0.05). The Bacteroidota and Bacillota were the major rumen bacterial phyla in all the groups, while at the genus level, Prevotella was dominant. Bacterial alpha diversity showed no significant differences among groups, with CMA samples clustering more tightly on PCoA. The findings demonstrate that the CMA combination effectively utilizes CS while optimizing rumen fermentation and growth performance, offering a viable strategy for enhancing its feed value.