In Vitro Evaluation of Chito-Oligosaccharides on Disappearance Rate of Nutrients, Rumen Fermentation Parameters, and Micro-Flora of Beef Cattle.

Simple Summary: This study investigated whether COS in the diet can improve the digestion and rumen health of beef cattle under in vitro fermentation conditions. A total of 24 fermentation tanks were randomly allocated into four groups. Each treatment had six replicates, with one tank per replicate. Each group received a different concentration of 0.02% COS, 0.04% COS, 0.08% COS, and a control group (CON). The results demonstrated that the addition of COS facilitates a shift in rumen fermentation from the acetate model to the propionate model. This is achieved by influencing the microbial population, resulting in alterations to the fermentation level, nutrient disappearance rate, and gas production. These changes have the potential to enhance rumen health. The study aimed to investigate the effect of dietary chitosan oligosaccharides (COS) meal levels on the nutrient disappearance rate, rumen fermentation, and microflora of beef cattle in vitro. A total of 24 fermentation tanks were randomly divided into four treatments containing 0% COS (CON), 0.02% COS, 0.04% COS, and 0.08% COS for an 8-day experiment period, with each treatment comprising six replicates. The disappear rates of DM, CP, EE, and total gas production were quadratically increased with increasing COS levels. The disappear rates of DM, CP, EE, and ADF were greatest, whereas the total gas production was lowest in the 0.08% COS group. The pH, NH3-N, MCP, the content of propionate, isobutyrate, butyrate, valerate, and the A/P were quadratically increased with increasing COS levels, while the A/P were linearly decreased. The pH, MCP, and the content of propionate, and butyrate were highest, whereas the NH3-N and the content of acetate, isobutyrate, valerate, and the A/P were lowest in the 0.08% COS group. Microbiomics analysis showed that the rumen microbial diversity was not altered between the CON and the 0.08% COS group. However, the relative abundance of Methanosphaera, Ruminococcus, Endomicrobium, and Eubacterium groups was increased, and the relative abundance of pathogenic bacteria Dorea and Escherichia-Shigella showed a decrease in the 0.08% COS group. Overall, the 0.08% COS was the most effective among the three addition levels, resulting in an increase in the disappearance rate of in vitro fermented nutrients and improvements in rumen fermentation indexes and microbial communities. This, in turn, led to the maintenance of rumen health. [ABSTRACT FROM AUTHOR]