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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics and Animal Breeding » Research » Publications at this Location » Publication #107725
Title: DIVERGENT SELECTION FOR PREDICTED TRANSMITTING FOR TYPE IN HOLSTEINS. II. RESPONSE IN LINEAR TYPE AND YIELD TRAITS

Author
item DEGROOT, B. - UNIV. OF NEBRASKA-LINCOLN
item KEOWN, JEFFREY - UNIV. OF NEBRASKA-LINCOLN
item VAN VLECK, LLOYD

Submitted to: Journal Dairy Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Objective was to examine the response to divergent selection for PTAT (Predicted Transmitting Ability for Type) on linear type traits and production in Holsteins. For four generations, half of University of Nebraska research herd was bred to Holstein sires with PTAT > 1.50 and the remainder was bred to sires with PTAT < 1.25, with equal PTA for yield in both groups. Data on first lactation cows for 16 linear type traits, final score, and milk, fat, and protein yields were collected from 1986 to 1999. Estimated breeding values (EBV) were obtained from single trait analyses with an animal model. After obtaining estimates of genetic and residual variances, the EBV were averaged by generation for each line. Fixed effects were year and season in which a cow freshened in model for yield and date cows were classified, age in days at freshening as a linear covariate, and days in lactation at classification as linear and quadratic covariates in model for type. Animal genetic and residual were random effects in both models. Stature, strength, body depth, udder depth, fore udder attachment, rear udder height, rear udder width, udder cleft, and front teat placement were significantly different (P<.01) between lines in the third generation. Dairy form, rump angle, thurl width, rear legs-side view, rear legs-rear view, foot angle, and teat length were not significantly different between lines in the third generation. Mean difference of 3.80 for final score was significant (P<.01) between lines in the third generation. Milk and protein yields were not significantly different between lines in third generation. Fat yield was significantly different (P <.01) between lines in the third generation. Divergent selection on PTAT of sires had an influence on udder traits with little or no effect on body and yield traits.