Dietary n-3/n-6 polyunsaturated fatty acid ratio modulates dry matter intake and inflammation in transition cows through regulating rumen bacteria, liver lipid metabolism and signal transduction

N-3 polyunsaturated fatty acid have a positive effect on regulating energy metabolism and inflammation in humans,which provides new ideas for researchers in the field of animal husbandry.This study aimed to elucidate the mechanism of the n-3/n-6 PUFA ratio that increased dry matter intake (DMI) and attenuated inflammatory responses in transition cows.The results showed that high n-3/n-6 PUFA ratio supplemented cows in the prepartum phase down-regulated the NF-kB signaling pathway by reducing the relative abundance of gram-negative bacteria in the rumen and this lipopolysaccharide in the rumen and liver; in the postpartum phase, high n-3/n-6 PUFA ratio in diet further increased DMI by altering the level of appetite factor peptide tyrosine tyrosine and orexins in serum, which ameliorated the insulin resistance in liver. In conclusion, an elevated n-3/n-6 PUFA ratio in the diet increases DMI and alleviates inflammation, which fills a gap in the application of n-3 in dairy cattle nutrition.