USE OF USDA EXTENSION FACTORS FOR PREDICTING 305-DAY LACTATION PRODUCTION IN DAIRY CATTLE
نویسندگان
چکیده
منابع مشابه
Use of Test-day Milk Yield for Genetic Evaluation in Dairy Cattle: a Review
The use of appropriate method for genetic evaluation of dairy animals is an important aspect of dairy cattle production. Traditional 305-day lactation model does not account for the changes in environmental factors within 305-day lactation and may involve unjustified projection of incomplete lactations. The use of test-day model in the recent past has made it possible to economize the genetic e...
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Increasing feed costs and the desire to improve environmental stewardship have stimulated renewed interest in improving feed efficiency of livestock, including that of US dairy herds. For instance, USDA cost projections for corn and soybean meal suggest a 20% increase over 2010 pricing for a 16% protein mixed dairy cow ration in 2011, which may lead to a reduction in cow numbers to maintain pro...
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Multivariate factor analysis and principal component analysis were used to decompose the correlation matrix of test-day milk yields of 48,374 lactations of 21,721 Italian Simmental cows. Two common latent factors related to level of production in early lactation and lactation persistency, and 2 principal components associated with the whole lactation yield and persistency were obtained. Factor ...
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This study compared genetic evaluations from 3 test-day (TD) models with different assumptions about the environmental covariance structure for TD records and genetic evaluations from 305-d lactation records for dairy cows. Estimates of genetic values of 12,071 first-lactation Holstein cows were obtained with the 3 TD models using 106,472 TD records. The compound symmetry (CS) model was a simpl...
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ژورنال
عنوان ژورنال: Canadian Journal of Animal Science
سال: 1979
ISSN: 0008-3984,1918-1825
DOI: 10.4141/cjas79-107