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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 #107724
Title: DIVERGENT SELECTION FOR PREDICTED TRANSMITTING FOR TYPE IN HOLSTEINS: I. ESTIMATES FOR GENETIC PARAMETERS FOR 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 of Animal 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 effects of divergent selection for PTAT (Predicted Transmitting Ability for Type) on linear type traits and production in Holsteins. For four generations, half of the 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 traits for 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. Estimates of genetic parameters obtained from estimates of co(variance) components using REML. Fixed effects were year and season 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 the model. Heritability estimates for linear type traits ranged from 0.04 to 0.50. Final score, an milk, fat, and protein yields had heritability estimates of 0.39, 0.15, 0.25 and 0.05, respectively. Estimates of genetic correlations among linear type traits ranged from -0.79 to 1.00 and of phenotypic correlations ranged from -0.27 to 0.84. Estimates of genetic correlations of final score with milk, fat, and protein yields were 0.04, -0.16, and 0.10, respectively. Phenotypic correlations of final score with milk, fat, and protein yields were 0.17, 0.10, and 0.22, respectively. Final score was highly heritable. The small genetic correlations between final score and yield traits suggest that selection for increased final score should not be recommended to increase yield, but would not be antagonistic to yield.