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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 #107723
Title: GENETIC ANALYSIS OF MATURE COW WEIGHT OF CROSSBRED BEEF CATTLE COWS

Author
item ARANGO, J. - 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: 1/14/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Data from first four cycles (phase two) of the Germplasm Evaluation Program (MARC-USDA) were used to evaluate mature weight of F1 cows produced by crosses of 22 sire and two dam (Angus and Hereford) breeds. Weights were available from 2 - 8 yr of age. Cow weights (cw) (n=61789) and cow weights adjusted for condition score (cwa) were analyzed by REML. Different models were tested to evaluate sets of fixed effects and random effects. The fina model included cow line, age in years, season of measurement (1 to 4) and their interactions, year of birth and pregnancy-lactation code as fixed effects. Random effects included direct genetic and permanent environmental effects of the cow. Genetic maternal effects were negligible. Analyses of all data, by season, and by age, and bivariate analyses between pairs of seasons and ages were performed. Heritability estimates over all ages were .49 and .54 for cw and cwa. Heritability estimates ranged from .47 to .58 for cw by age and from .49 to .61 for cw by season. Permanent environmenta variances generally were about one third of those for genetic effects. Estimates of genetic and permanent environmental correlations converged to one for all pairs of seasons for cw. Estimates of genetic correlations exceeded .92 for all age combinations while those for permanent environmental effects ranged from .56 to 1.00, being smaller between extreme ages, for cw. Results for cwa were similar, with relatively higher heritabilities and smaller permanent environmental variances. Results suggest that cw is basically the same trait for all seasons within a year, as well as for all ages. A repeatability model seems to suffice to model cow weight in this population.