Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/1996
Publication Date: N/A
Interpretive Summary: Accurate genetic parameters are needed for calculating reliable genetic evaluations and determining the genetic merit of dairy goats for conformation traits of interest to breeders. Although conformation data have been collected for dairy goats since 1977 and genetic evaluations calculated since 1986, parameter values for non-Holstein dairy cattle were used in the evaluations because estimates were not available for dairy goats. This study estimated genetic parameters for final score and 13 conformation traits (stature, strength, dairyness, rump angle, rump width, rear legs, fore udder attachment, rear udder height, rear udder arch, suspensory ligament, udder depth, teat placement, and teat diameter) based on data from seven dairy goat breeds (Alpine, Experimental, LaMancha, Nubian, Oberhasli, Saanen, and Toggenburg). The new parameters will be the basis for genetic evaluations under an updated evaluation methodology that will result in more accurate ranking of animals. This improved ranking will allow dairy goat breeders to make greater genetic progress for conformation traits.
Technical Abstract: Covariance components for final score and 13 linear type traits of seven dairy goat breeds (Alpine, Experimental, LaMancha, Nubian, Oberhasli, Saanen, and Toggenburg) were estimated by multitrait restricted maximum likelihood using a canonical transformation method with an animal model. Data were 21,322 records from appraisals from 1988 to 1993. Heritabilities were estimated as .20 for final score, .46 for stature, .25 for strength, .24 for dairyness, .44 for rump angle, .25 for rump width, .26 for rear legs, .28 for fore udder attachment, .25 for rear udder height, .31 for rear udder arch, .20 for suspensory ligament, .35 for udder depth, .58 for teat placement, and .38 for teat diameter. Genetic correlations of linear type traits with final score were positive except for udder depth ( .11) and rear legs ( .08); largest positive correlation was .49 for fore udder attachment. Largest positive correlation among type traits was .75 for stature and rump width; largest negative correlation was .44 for udder depth and suspensory ligament. Mean predicted transmitting ability of bucks for individual traits varied among breeds, but reliabilities were similar. Correlations between predicted transmitting abilities calculated with animal and sire models ranged from .19 to .74 for bucks with a reliability of 30% or higher and generally were highest for final score.