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United States Department of Agriculture

Agricultural Research Service

Title: Genetic and Phenotypic (Co) Variances for Growth Traits of Intact Male Populations of Purebred and Composite Beef Cattle

Authors
item Gregory, Keith
item Cundiff, Larry
item Koch Robert M, - UNIV OF NEBRASKA

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 1995
Publication Date: N/A

Interpretive Summary: Lack of uniformity of product is a problem of the beef industry. Composite breeds of cattle are similar to their contributing purebreds in phenotypic coefficients of variation and in genetic variation for growth and size. Heritability of subjective scores for anatomical traits approach those for different measures of growth and size. Estimates of heritability for calving difficulty score are higher in calves with 2 yr old dams than with dams greater than or equal to 3 yr old and are sufficiently high (.27 plus/ minus .08) to be a useful selection criterion for reducing calving difficulty. Because the genetic correlation between birth weight and calving difficulty score is higher than the genetic correlation between birth weight and 368-d weight there is opportunity to reduce calving difficulty by reducing birth weight while maintaining 368-d weight. Even though the genetic correlation between gestation length and birth weight is low (.21 plus/minus .11), gestation length has a relatively high genetic correlation with calving difficulty score (.57 plus/minus .18) in females greater than or equal to 3 yr old.

Technical Abstract: Genetic and phenotypic parameters were estimated for 9 purebreds and 4 generations of 3 composite populations to which the 9 purebreeds contrib- uted. Phenotypic coefficients of variation and genetic standard deviations were not different between composites and contributing pure- breeds. Estimates of heritability for calving difficulty score for calves with 2 yr old dams were sufficiently high (.27 plus/minus .08) to be a useful selection criterion for reducing calving difficulty. Because the genetic correlation between birth weight and calving difficulty score is higher than the genetic correlation between birth weight and 368-d weight there is opportunity to reduce calving difficulty by reducing birth weight while maintaining 368-d weight. Even though the genetic correlation between gestation length with birth weight was low (.21 plus/ minus .11), it was (.57 plus/minus .18), with calving difficulty score for calves with dams greater than or equal to 3 yr old. Phenotypic correlations were relatively high among growth and size traits and were intermediate between birth weight and calving difficulty score in calves with 2 yr old dams (.53), but were lower for calves with dams in other age classes.

Last Modified: 4/17/2014
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