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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 #161201
Title: AGE-OF-DAM ADJUSTMENT FACTORS FOR BIRTH AND WEANING WEIGHT RECORDS OF BEEF CATTLE: A REVIEW

Author
item RUMPH, JANICE - UNIV. OF NEBR-LINCOLN
item Van Vleck, Lloyd

Submitted to: Genetics and Molecular Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2004
Publication Date: 2/27/2004
Citation: RUMPH, J.M., VAN VLECK, L.D. AGE-OF-DAM ADJUSTMENT FACTORS FOR BIRTH AND WEANING WEIGHT RECORDS OF BEEF CATTLE: A REVIEW. GENETICS AND MOLECULAR RESEARCH. 2004. 3(1):1-17.

Interpretive Summary: Age-of-dam adjustment factors are used to preadjust birth and weaning weight data for national beef cattle genetic evaluations. Adjustments are used in order to make the means of the different age of dam subclasses similar so that a fair genetic evaluation of animals can be performed. This paper reviews several research studies that have estimated age-of-dam adjustment factors for birth weight and weaning weight of beef cattle. In general, age-of-dam adjustment factors for birth weight were similar for both sexes, but age-of-dam adjustment factors for weaning weight differed with heifer calves requiring smaller adjustments than male calves. Adjustment factors for age-of-dam effects varied greatly across breeds. Preadjustment of records for age-of-dam effects differences is difficult because a perfect estimate of adjustments is not possible. A more appropriate method for adjusting for age-of-dam may be to simultaneously adjust during national genetic evaluations, i.e., include age-of-dam by sex effects in the model for prediction of genetic values.

Technical Abstract: Age-of-dam adjustment factors are used to preadjust birth and weaning weight data for national beef cattle genetic evaluations. Adjustments are used in order to make the means of the different age of dam subclasses similar so that a fair comparison of animals can be performed. This paper reviews several research studies that have estimated age-of-dam adjustment factors for birth weight and weaning weight of beef cattle. In general, age-of-dam adjustment factors for birth weight were similar for both sexes, but age-of-dam adjustment factors for weaning weight differed with heifer calves requiring smaller adjustments than male calves. Adjustment factors for age-of-dam varied greatly across breeds. Preadjustment of records for age-of-dam differences is difficult because a perfect estimate of adjustments is not possible. A more appropriate method for adjusting for age-of-dam may be to simultaneously adjust during national genetic evaluations, i.e., include age-of-dam by sex effects in the model for prediction of genetic values.