ARS | Publication request: Genetic relationships among milk production and teat and udder scores in cows sired by seven prominent beef cattle breeds

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2013
Publication Date: N/A

Technical Abstract: Milk production and teat and udder quality are key components to lifetime cow productivity in commercial beef cattle. Our objective was to determine genetic relationships and breed differences for milk production and teat and udder quality in young and mature cows. Cows (n = 602) were crosses of F1 cows and bulls (F1**2); the F1 parents resulted from matings of industry Angus, Hereford, Red Angus, Charolais, Gelbvieh, Limousin, and Simmental bulls with base Hereford, Angus, and MARC III composite cows. These F1**2 cows were produced in three seasons and evaluated as 2 yr olds after their first calf and again as 5 yr olds. Milk production was measured approximately 100 d after parturition using the weigh-suckle-weigh method. Teat size and udder suspension were scored on a 9-point subjective scale in which 5 was considered an optimum. Genetic correlations and breed effects were derived from MTDFREML using a mixed model with fixed season, calf sex (for milk production), and breed and heterosis covariates and random effects of animal and error. Heritability estimates for 2 and 5 yr teat score, 2 and 5 yr udder score, and 2 and 5 yr milk production were 0.27, 0.31, 0.14, 0.32, 0.32 and 0.49. Genetic correlations among the same trait measured in different years were high (0.79 to 0.84). Similar to heritability estimates, correlations with udder score at 2 yr were lower than for other score traits likely indicating greater error in phenotyping udder suspension at 2 yr. Correlations between score traits and milk production were low and not significantly different than zero. Teat size was smallest in Charolais and largest in Simmental across years. Udder suspension was most optimal in Charolais. No breed effects were detected for milk production. This result is counter to breed effects generally observed on maternal effects for weaning weight in national cattle evaluation. Selection for these traits may lead to increased lifecycle productivity in beef cattle due to decreased culling on udder conformation.