Use of test day yields for genetic evaluation of dairy sires and cows
作者： Ewa Ptak , L.R. Schaeffer
DOI: 10.1016/0301-6226(93)90033-E
关键词: Dairy cattle 、 Lactation 、 Test day 、 Biology 、 Herd 、 Milk production 、 Homogeneous 、 Ice calving 、 Animal science 、 Covariate
摘要: Abstract Genetic evaluations of dairy sires and cows for milk production based on 305-day lactation yields were compared to the corresponding test day from those lactations. First data Quebec Dairy Herd Analysis Service 3094 calving September 1983 October 1989. There 29462 yield records. Four animal models studied use with yields, each model included four covariates account shape curve within eight age-season groups. Models contained either herd-year-season effects or herd-test date effects, residual variances assumed be homogeneous heterogeneous across days in milk. Herd-test resulted lower effects. Correlations ranged 0.87 0.97. offer many advantages over lactations including better modeling factors affecting no need extend records, possibly greater accuracy evaluations.
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