This study profiled the nutritional, safety, and metabolic evolution of milk from Chuanzhong Black (CBG) and Jianzhou Big-Ear (JBG) goats during early lactation (days 1–35). Results revealed that colostrum in both breeds contained superior levels of total solids, fat, and protein compared to mature milk. Notably, CBG colostrum exhibited significantly higher IgG concentrations (81.29 mg/mL) than JBG, indicating stronger passive immunity potential. However, safety analysis showed that Aflatoxin M1 (AFM1) concentrations also peaked in colostrum. Untargeted metabolomics identified 804 (in CBGs) and 790 (in JBGs) differentially expressed metabolites (DEMs), revealing a distinct functional shift from immunity-supporting compounds in colostrum to energy-provision metabolites in mature milk. Additionally, CBG generally displayed elevated metabolite levels compared to JBG. These findings confirm that milk quality is strictly governed by both breed and lactation stage, providing valuable metabolic insights for evaluating milk quality and establishing baseline grading standards for meat goats.
Yue et al. (Fri,) studied this question.