论文部分内容阅读
The objectives of this study were to estimate genetic parameters of lactation average somatic cel scores (LSCS) and examine genetic associations between LSCS and production traits in the ifrst three lactations of Chinese Holstein cows using single-parity multi-trait animal model and multi-trait repeatability animal model. There were totaly 273605 lactation records of Chinese Holstein cows with ifrst calving from 2001 to 2012. Heritability estimates for LSCS ranged from 0.144 to 0.187. Genetic correlations between LSCS and 305 days milk, protein percentage and fat percentage were –0.079,–0.082 and –0.135, respectively. Phenotypic correlation between LSCS and 305 days milk yield was negative (–0.103 to –0.190). Genetic correlation between 305 days milk and fat percentage or protein percentage was highly negative. Genetic correlation between milk fat percentage and milk protein percentage was highly favorable. Heritabilities of production traits decreased with increase of parity, whereas heritability of LSCS increased with increase of parity.