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Title: GENETIC PARAMETERS FOR GROWTH AND REPRODUCTIVE TRAITS OF CROSSBRED HEIFERS

Author
item SPLAN, R. - UNIV. OF NEBRASKA-LINCOLN
item Cundiff, Larry
item Van Vleck, Lloyd

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Data on growth and reproductive traits were obtained on 2936 crossbred heifers from the U. S. Meat Animal Research Center. Genetic parameters were estimated for 205-day weight (WWT, kg), 365-day weight (YWT, kg), age at puberty (PUB, d), calving rate (RATE, 0 or 1), calving difficulty of first calf (DIFF, 0 or 1) and birth weight of first calf (CBWT, kg). All traits were considered traits of the heifer. Estimates of heritability for WWT, YWT, PUB and RATE were obtained using Restricted Maximum Likelihood with a sire model that included fixed effects of age of dam, year of birth, line (breed composition) of sire and line of dam. The model for WWT and YWT incorporated covariate of birth date, and model for WWT, YWT and PUB included heifer's dam as an uncorrelated random effect. Model for DIFF and CBWT included fixed effects of sex of calf, year of birth and line of calf, and covariate for calf's birth date with heifer's dam as an uncorrelated random effect. Estimates of heritability for WWT, YWT, PUB, RATE, DIFF and CBWT were .18, .43, .43, .08, .12 and .27. Phenotypic variances were 3428, 5126, 1652, .1459, .1933 and 79.43. Variances due to dam effects as proportions of phenotypic variances for WWT, YWT, PUB, DIFF and CBWT were .36, .27, .12, .06 and .06. Most heritability estimates were consistent with previous literature estimates. RATE had low heritability but enough variation to allow possible selection. Genetic correlations between weight and reproductive traits ranged from -.03 to .10. Estimates of genetic correlations among weights were high and positive, as was estimate between CBWT and DIFF. Estimated genetic correlations suggest selection for decreased age at puberty would result in slightly increased RATE, but also increased DIFF.