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Journal of Dairy Science Vol. 65 No. 8 1601-1611
© 1982 by American Dairy Science Association ®
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Genetic and Phenotypic Aspects of Health Traits by Lactation1

R. D. Shanks, P. J. Berger, A. E. Freeman and F. N. Dickinson

Department of Dairy Science, University of Illionois, Urbana 61801
Department of Animal Science, Iowa State University, Ames 50011
AIPL, USDA, Beltsville, MD 20705

ABSTRACT

Heritabilities and genetic and phenotypic correlations among predicted costs and incidences of health traits were calculated by lactation. Health traits were categorized total, mammary, reproductive, locomotive, and other. Dairy Herd Improvement data from 62,112 records on progeny by 323 sires were analyzed. Costs and incidences for health traits were estimated for each lactation record from information on postpartum length, milk yield, lactation number, termination status, calving age, and days dry. Most heritabilities were less than .10 in the first three lactations. Heritabilities of mammary cost and incidence declined with lactation number. Heritabilities of other health costs and incidences increased with lactation. Genetic and phenotypic correlations between cost and incidence wthin category were high. Genetic correlations between total health cost and total health incidence were greater than .90 in all lactations. The low heritabilities and high correlations imply that accurate sire evaluation for health traits would require large numbers of progeny per sire with information on either health cost or health incidence.

FOOTNOTES

1 Journal Paper No. J-10129 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Project No. 1053, a contributing project to North Central Regional Project, NC-2, Improvement of Dairy Cattle Through Breeding.






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Copyright © 1982 by the American Dairy Science Association ®.