Abstract
This study aims to explore the impact of adding sodium acetate and sodium butyrate on the composition, blood biochemical parameters, and volatile flavor compounds of lactating mares' milk. By assessing the influence of these additives on milk flavor enhancement, the findings provide scientific evidence for optimizing flavor characteristics and offer new strategies for improving the sensory attributes of mare milk products. Eighteen lactating Yili mares were randomly assigned to three groups: a control group, a sodium acetate group (85 mg/kg·BM(-1)), and a sodium butyrate group (85 mg/kg·BM(-1)). The experiment lasted 90 days, with milk yield recorded on days 0, 30, 60, and 90. Milk samples were collected on day 60 (peak lactation) for compositional analysis, and GC-IMS was employed to identify and quantify volatile compounds. Additionally, blood samples were drawn from the jugular vein before morning feeding on day 60 using heparinized tubes to assess key biochemical markers, including glucose, triglycerides, total cholesterol, and urea. The results revealed the following findings: (1) Milk yield and composition: The addition of sodium acetate and sodium butyrate had no significant effect on milk yield. However, both treatment groups exhibited significantly or extremely significantly higher milk fat content compared to the control group, whereas milk protein and lactose levels remained largely unchanged. (2) Blood biochemical indicators: The sodium butyrate group showed an extremely significant increase in urea levels compared to the sodium acetate and control groups. Glucose levels in the sodium acetate group were also significantly higher than in the control group. Moreover, triglyceride levels were markedly elevated in the sodium butyrate group compared to the sodium acetate group, while total bilirubin concentrations were significantly higher in the sodium acetate group than in the control group. (3) Volatile compounds: The addition of these additives led to a significant increase in the diversity and concentration of volatile compounds in mare milk. Notably, esters, aldehydes, and ketones showed substantial enrichment in both treatment groups. The relative abundance of esters such as butyl acetate, L-lactic acid ethyl ester, 1-pentene-3-ol, pentanol, and 3-pentanone increased, alongside a significant rise in aldehydes and ketones, including 2-heptenal and 3-pentanone. In conclusion, sodium acetate and sodium butyrate enhance milk flavor by modulating milk composition and metabolic parameters, providing a scientific foundation for improving the quality of mare milk products.