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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #100594
Title: COMPARING GENETIC EVALUATIONS ACROSS BREEDS

Author
item Macneil, Michael
item Cundiff, Larry
item Van Vleck, Lloyd

Submitted to: Hereford American
Publication Type: Popular Publication
Publication Acceptance Date: 5/1/1999
Publication Date: N/A
Citation: MACNEIL, M.D., CUNDIFF, L.V., VAN VLECK, L.D. COMPARING GENETIC EVALUATIONS ACROSS BREEDS. HEREFORD AMERICAN. 1999. v. 4(4). p. 4-5.

Interpretive Summary: Expected progeny differences (EPD) estimate differences in performance anticipated in future progeny of sires or dams. While EPD are the best available tools for comparing genetic merit of individuals within a breed, they do not provide a straightforward comparison of animals in different breeds. This problem is most acute for commercial producers who may want bulls of comparable genetic merit from two or more breeds for use in crossbreeding. Several factors complicate comparing EPD across breeds. Published EPD do not reflect 1) average breed differences, 2) differences between breeds in how the base point is defined, or 3) differences in genetic trend from breed to breed. Scientists have developed methods to put within-breed EPD for several breeds on the same scale. These procedures result in across-breed EPD (AB-EPD). They rely on data from 1) breed associations conducting genetic evaluations, and 2) records of performance of progeny of several sires from each breed fairly compared with each other. The Germ Plasm Evaluation Program at Clay Center, NE has been the basis for comparing sires of the different breeds under the same conditions in Nebraska. Various statistical analyses estimate the breed differences, differences in base points, and differences in genetic trend. Resulting adjustment factors can be applied to EPD calculated by breed associations. The AB- EPD are slightly less accurate than within-breed EPD. However, use of AB-EPD has no effect on within-breed comparisons. Bias is unlikely to be a problem in AB-EPD for growth traits.

Technical Abstract: Expected progeny differences (EPD) estimate differences in performance anticipated in future progeny of sires or dams. While EPD are the best available tools for comparing genetic merit of individuals within a breed, they do not provide a straightforward comparison of animals in different breeds. This problem is most acute for commercial producers who may want bulls of comparable genetic merit from two or more breeds for use in crossbreeding. Several factors complicate comparing EPD across breeds. Published EPD do not reflect 1) average breed differences, 2) differences between breeds in how the base point is defined, or 3) differences in genetic trend from breed to breed. Scientists have developed methods to put within-breed EPD for several breeds on the same scale. These procedures result in across-breed EPD (AB-EPD). They rely on data from 1) breed associations conducting genetic evaluations, and 2) records of performance of progeny of several sires from each breed fairly compared with each other. The Germ Plasm Evaluation Program at Clay Center, NE has been the basis for comparing sires of the different breeds under the same conditions in Nebraska. Various statistical analyses estimate the breed differences, differences in base points, and differences in genetic trend. Resulting adjustment factors can be applied to EPD calculated by breed associations. The AB- EPD are slightly less accurate than within-breed EPD. However, use of AB-EPD has no effect on within-breed comparisons. Bias is unlikely to be a problem in AB-EPD for growth traits.