Estimation of Genetic Parameters and Stability for Milk Production Traits in Huaxi Cattle from the Xinjiang Region

The daily milk yield (DMY) is defined as the sum of milk produced during morning, midday, and evening milkings. This metric is the key parameter for quantifying a cow's absolute production level and serves as the foundation for calculating economic traits such as 305-day total milk yield, fat yield, and protein yield, making it essential for evaluating lactation performance. Based on the data cleaning pipeline, 2992 valid records were retained from 3332 initial records through rigorous quality-control screening, this study systematically evaluated three critical lactation traits-daily milk yield and its milk components (milk fat percentage and milk protein percentage)-using complete lactation records from Huaxi cows and estimated their phenotypic and genetic parameters. Non-genetic factors (parity, season, and mature body weight) were corrected via the MIXED procedure coupled with a multi-trait animal model. The results showed that all considered non-genetic factors significantly influenced the lactation traits (p < 0.05), while daily milk yield (DMY), milk fat percentage (FP), and milk protein percentage (PP) all exhibited moderate to high heritability (0.29-0.38) (p < 0.01). Genetic evaluation of DMY and its milk components provides quantitative evidence for precision selection and optimized mating decisions in the Huaxi dairy population, thereby accelerating genetic progress in milk production, improving herd profitability, and promoting the development of the regional dairy industry.