Submitted to: American Dairy Science Association Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 7/26/2000
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Genetic evaluations of dairy goats are computed annually from records available through Dairy Herd Improvement (DHI) and the American Dairy Goat Association (ADGA). During 1999, 11,273 does were enrolled in DHI test plans used in genetic evaluations; 3784 does participated in linear appraisal programs. For evaluation of yield traits, an animal model similar to that used for dairy cattle is used, but analysis is across breeds. Lactation records for the first 6 parities of does born since July 1973 and kidded since January 1976 are edited within limits appropriate for goats, projected to 305 days, and adjusted for kidding age and month. Evaluations are computed for milk, fat, and protein yields and component percentages; an economic index for milk, fat, and protein (MFP$) is calculated based on economic values for dairy cattle. A multitrait animal model is applied to 14 linear type traits and final score. Through canonical transformation, a single-trait calculation method is used. Annual genetic progress for does born in 1996 as a percentage of mean breed yield was lowest for Toggenburgs (-.1, milk; .0, fat, protein) and highest for Saanens (.9, milk, protein; 1.0, fat). Corresponding trend for type traits across breeds was .67, stature; .37, rump angle; .34, teat placement; .22, suspensory ligament; .20, strength; .12, rump width, fore udder width; .16, teat diameter; .09, rear legs; .06, dairyness; .05, final score; .02, fore udder attachment; and .01, udder depth. Two production-type indexes are computed by ADGA with 2:1 and 1:2 weightings for MFP$ and predicted transmitting ability for final score. Based on developments for dairy cattle, test-day data eventually will be used directly in a test-day model for genetic evaluation of yield traits.