Optimization of Artemisia ordosica crude polysaccharides on milk fatty acid composition in lactating donkeys and their effects on rectal microbiome and lactation performance

Compared with the CON group, AOCP supplementation significantly enhanced lactation performance (milk yield, fat, lactose) and the digestibility of DM, ADF, NDF, and elevated oleic acid, linoleic acid, eicosapentaenoic acid, as well as the unsaturated-to-saturated (U/S) and polyunsaturated-to-saturated (P/S) fatty acid ratios, while reducing saturated fatty acids and the c index. AOCP elevated acetate and butyrate in the rectum and the activity of enzymes related to lipid metabolism such as stearoyl-CoA desaturase, and increased the relative abundance of beneficial bacteria (<i>Eubacterium hallii group</i>, <i>Prevotella</i>, <i>Ruminococcus</i>), while decreasing potentially pathogenic bacteria <i>Streptococcus</i> and <i>norank_f_Lachnospiraceae</i>. In summary, AOCP may optimize the fatty acid composition of donkey milk and enhance lactation performance by modulating rectal bacteria structure, enzymes related to lipid metabolism, and nutrient utilization.