Authors: SONGBAI LIU, HUIZE TAN, LU YANG, JIANMING YI
Abstract: Phenotypic and genetic parameters among udder traits (udder depth, UD; median suspensory line, MS; fore udder attachment, FUA; rear udder height, RUH; rear udder width, RUW), final score (FS), and milk production traits (305-day milk yield, 305 DM; 305-day milk-fat yield, 305 DF; 305-day milk-protein yield, 305 DP) were estimated using a derivative-free restricted maximum likelihood procedure with an animal model. The results showed that heritability estimates for selected traits ranged from 0.11 to 0.24. Strong positive genetic correlations were observed for MS, RUH, and RUW with FS (0.42-0.72). A positive genetic relationship was also estimated between MS and 305 DM (0.79). The genetic correlation between UD and 305 DM was -0.20. Positive genetic correlations were found between RUW and milk production traits (0.44-0.89). RUH also had positive genetic relationships with 305 DM (0.27) and 305 DF (0.16). Moderate positive genetic correlations were estimated between FS and milk production traits (0.25-0.35). The genetic parameters calculated from field records will provide valuable information for genetic improvement in type and milk production traits of Holstein cattle in southern China.
Keywords: Dairy cattle, udder traits, milk production traits, genetic parameter
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