Effects of parity, age, and stage of lactation at classification on linear type scores of Holstein cattle.
Linear type scores of 60,121 Michigan and Wisconsin cows classified from January through November 1983 were obtained from the Holstein-Friesian Association of America. Joint effects of parity, age, and stage of lactation at classification on linear scores of Holstein body conformation characteristics were examined. The mixed model used had a random factor of sire within herd and had fixed factors of herd and the three-way subclass of parity, age, and stage of lactation. Herd effect included differences due to herd environment, classifier, and season. Sires within herds and herds were absorbed while constructing equations for the three-way subclass factors. Parity, age, and stage of lactation affected linear type scores after adjustment for herd and sire differences. There was little evidence of a parity by stage interaction or a parity by age interaction. Adjustment factors for the three-way subclass effects were derived. When compared with adjustment factors derived in this study, current adjustment factors overadjust for age and parity effects and underadjust for stage of lactation effects.
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Department of Animal Science, Michigan State University, East Lansing 48824-1225.
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D000375:Aging; D000818:Animals; D001824:Body Constitution; D002417:Cattle / Q000145:classification*; D005260:Female; D007774:Lactation; D010298:Parity; D011247:Pregnancy