Abstract
This study looked at how methionine (Met) affects on serum biochemical indicators, antioxidant indicators, and the fecal microbiota of lactating donkeys. A total of 18 healthy donkeys at the mid-lactation stage were used in this study. They were given concentrate meals with varying concentrations of Met after being randomly split into three groups: Met group I (M1) received 5 g/d of Met, Met group II (M2) received 15 g/d of Met, and the control group (C) received 0 g/d of Met. The trial lasted for five weeks in total. Fecal microbes, antioxidant markers, and blood biochemical indicators were examined. The findings showed that while the levels of malondialdehyde (MDA) decreased (p < 0.05), the addition of Met (15 g/d) significantly enhanced the total antioxidant capacity (T-AOC) and catalase (CAT) activity. Milk samples from the different groups trended towards having significant differences in the levels of the serum biochemical indicators albumin (ALB) and lactate dehydrogenase (LDH) (0.05 < p < 0.1). A fecal microbiome analysis revealed that the addition of Met (5 g/d) increased the abundance of Methanocorpusculum and Ruminococcus, and the addition of 15 g/d of Met increased the abundance of Ruminococcus, Peptococcus, and Anaeroplasma while decreasing the abundance of the [Eubacterium]_ruminantium_group. A correlation analysis revealed that Ruminococcus and Methanocorpusculum were positively correlated with the T-AOC and CAT activity (M1 group). Peptococcus was significantly negatively correlated with MDA levels and positively correlated with the T-AOC (M2 group). Anaeroplasma was positively correlated with CAT activity (M2 group). The above results indicated that Met increased donkey antioxidant levels and modulated the abundance of the fecal microbial community. These findings lay the groundwork for boosting the production performance and general health of nursing donkeys.