As a lactation source, donkey milk contains a higher percentage of n-3 polyunsaturated fatty acids in the milk fatty acid profile than cow’s milk, especially the percentage of α-linolenic acid (ALA). We hypothesized that the ratio of dietary concentrate/roughage could influence the composition of the fatty acid (FA) profile of donkey milk, and that the substitution of low-quality roughage with high-quality roughage could improve the composition of the polyunsaturated fatty acid profile of donkey milk. The purpose of this experiment was to investigate the effects of the partial dietary replacement of low-quality roughage with alfalfa hay to increase the proportion of roughage in the diet on the FA profiles in the milk of lactating donkeys, with the goal of optimizing the FA profiles of donkey milk. The trial design was a single-factor randomized design. Sixteen Dezhou donkeys of similar age, weight, parity, and lactation days were selected and equally divided (n = 8 per group) into a low alfalfa hay group (LG, 40 concentrate/60 roughage, alfalfa hay: 44.85 g/kg dry matter) and a high alfalfa hay group (HG, 30 concentrate/70 roughage, alfalfa hay: 179.48 g/kg dry matter). The trial lasted 8 weeks and the energy and protein levels of the two diets were identical. The results showed that the profile of milk ALA increased (p = 0.048) and the n-6/n-3 ratio and index of thrombogenicity were decreased (p = 0.019 and p = 0.002) in the HG. Partial replacement of low-quality roughage with alfalfa hay and increasing the percentage of dietary roughage from 60% to 70% optimized the FA quality of donkey milk fat.

This study evaluated the effects of dietary selenium (Se) supplementation on lactation performance, milk fatty acid composition, and rectal microbiota and short-chain fatty acids in lactating Dezhou donkeys to determine the optimal dose. Twenty-four lactating Dezhou donkeys (estimated milk yield: 3.60 ± 0.84 kg/d; days in milk: 39.93 ± 7.02 d; body weight: 247.24 ± 26.27 kg; parity: 2.82 ± 0.48) were randomly divided into four groups (n = 6): CON (0 mg Se/kg DM), Se1 (0.15 mg Se/kg DM), Se2 (0.3 mg Se/kg DM), and Se3 (0.5 mg Se/kg DM), and were supplemented with Se yeast in the basal diet. The results showed that plasma Se concentrations increased dose-dependently. The Se2 group significantly increased milk yield, milk component yield, milk protein production efficiency, milk production efficiency, the digestibility of acid detergent fiber and neutral detergent fiber, protein biological value, and nitrogen metabolic rate, as well as the proportions of C18:1c9, C18:2c6, unsaturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, n-3 long-chain polyunsaturated fatty acids, the ratio of unsaturated to saturated fatty acids, the ratio of polyunsaturated to saturated fatty acids (P/S), desirable fatty acids, and (C18:0 + C18:1)/C16:0 in donkey milk, while decreasing the proportion of saturated fatty acids, atherogenicity index, and thrombogenic index. The Se2 group also increased acetate and butyrate in rectal feces, and promoted the growth of beneficial bacteria, including Christensenellaceae R-7 group, Lachnospiraceae XPB1014, and norank_f_Erysipelotrichaceae. In summary, the effects of Se supplementation were dose-dependent: 0.3 mg Se/kg DM improved milk performance and optimized milk fatty acid profiles by improving nutrient digestion and metabolism and modulating rectal bacteria structure, whereas 0.5 mg Se/kg DM showed no lactation benefits (with potential inhibitory effects) despite improving the P/S ratio and reducing the atherogenicity and thrombogenic indices.

Our study investigated the improved nutritional quality and physicochemical properties in meat, as well as growth performance and antioxidant capacity in meat donkeys, from dietary selenium (Se) yeast (SY), modulating cecal microbiota and multi-omics profiles. A total of 16 one-year-old male meat donkeys (120 ± 25 kg) were allocated to two groups: SS (0.3 mg/kg inorganic Se from sodium Se) and SY (0.3 mg/kg organic Se from SY). SY supplementation significantly increased Se and crude protein content, water-holding capacity, and cooking loss, but reduced ether extract content, shear force, and drip loss of donkey meat; SY also improved body weight, nutrient digestibility, beneficial bacteria (Agathobacter, Lactobacillus), and antioxidant enzyme activities, while reducing pro-inflammatory cytokines and malondialdehyde. Metabolomics revealed upregulation of sphingosine-1 phosphate (S1P), and transcriptomics identified enrichment of the PI3K-Akt pathway. Validation confirmed that SY elevated S1P levels and upregulated S1P receptor 2 (S1PR2) and PI3K-Akt-related genes. In conclusion, meat quality and antioxidant capacity were enhanced, and cecal microbiota in donkeys were reshaped by dietary SY. These findings indicate that dietary selenium supplementation increases Se deposition and improves the quality of donkey meat, providing a promising approach for the development of Se-enriched, value-added functional donkey meat products and processed meat items.