17. A 22:6 n-3 Rich Supplement Affects the Ruminal Microbial Community and Fermentation and Alters Plasma Metabolites

This study investigated the effects of a 22:6 n-3 rich supplement on ruminal fermentation characteristics and microbial changes, and also the effects of a 22:6 n-3 rich supplement on plasma metabolites by using rumen cannulated wether goats in a 4×4 Latin square design. The 22:6 n-3 rich supplement was infused into the rumen of the goats twice daily in equal portions at a rate of 0.0, 2.5, 5.0 and 10.0 g/d [corresponding to 0, 0.4%, 0.8% and 1.5% of diets (dry material base), respectively]. The concentration of NH₃-N and total volatile fatty acid (TVFA), and the molar proportions of acetate and butyrate were decreased by the supplement (P<0.001). The supplement decreased diversity of the rumen bacterial community (P<0.01), and reduced the abundance of Ruminococcus flavefaciens, R. albus, Fibrobacter succinogenes and protozoa (P<0.01). However, it increased the abundance of ruminal fungi (P<0.01). The supplement had no influence on the concentration of plasma glucose, HDL-cholesterol, LDL-cholesterol and urea but increased the concentration of triglycerides and total cholesterol (P<0.05). In conclusion, the 22:6 n-3 rich supplement inhibited ruminal fermentation and this was accompanied by the decrease of the abundance of ruminal microbes, and also affected plasma metabolites.