Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/27/1999
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Genetic evaluations of dairy goats are computed annually by USDA from data available through the American Dairy Goat Association (ADGA) and the Dairy Herd Improvement system. Number of does in test plans acceptable for use in evaluation was 12,951 in 1997; participation in appraisal programs was 4508 does. For evaluation of yield traits, an animal model similar to that for dairy cattle is used, but analysis is across breeds. Lactation records for the 1st 6 parities of does born since July 1973 and kidding since Jan. 1976 are edited with 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 index for milk, fat, and protein (MFP$) is calculated based on economic values for dairy cattle. A multitrait animal model is applied to 14 linear type traits and final score. By applying canonical transformation, a single-trait calculation method can be used. Annual genetic progress as percentage of mean breed yield ranged from .0% for milk and protein and -.2% for fat for Toggenburgs to .9% for milk and fat and .8% for protein for Nubians. Trend for type traits across breeds for does born in 1995 was .6 for stature; .4 for rump angle; .3 for teat placement; .2 for strength, teat diameter, and suspensory ligament; .1 for rump width; .0 for final score, dairyness, fore udder attachment, rear udder arch, udder depth; and -.1 for rear legs and rear udder height. Two production-type indexes are computed by ADGA with 2:1 and 1:2 weightings for MFP$ and predicted transmitting ability for final score. A test day model that is being developed for yield traits of dairy cattle will be adapted for dairy goats to account better for environment, testing variation, and differences in lactation curves.