Length of Productive Life of Dairy Cows. 2. Variance Component Estimation and Sire Evaluation
نویسندگان
چکیده
منابع مشابه
Effect of Heterogeneity of Variance on Dairy Sire Evaluation
The effects of heterogeneity of variance among herds on dairy sire evaluation were examined. Data consisted of 111,196 first lactation Holstein production records of heifers calving in Ontario between 1978 and 1983. To account for selection, older sires without first crop daughters in the data were treated as fixed effects. Herds were classified into one of nine groups based on their estimated ...
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Complete longevity data are available too late for most sire selection. Earlier selection is possible using correlated traits, nonlinear evaluation of censored data, or predicted longevities for live cows in addition to completed longevity data. Completed longevity was defined as total months in milk by 84 mo of age. Predicted longevity was computed by multiple regression from cows alive at six...
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Data from a survey performed from 1986 to 1990 were analyzed to assess the effects of diseases on length of productive life of 3589 Holstein cows from 47 herds, using a proportional hazard model. The probability of a cow being culled, or hazard function, was supposed to be the product of an unspecified baseline hazard function and log-linear, time-dependent explanatory variables that possibly i...
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Covariance components for final score and 13 linear type traits of dairy goats were estimated by multitrait REML using canonical transformation with an animal model. Data were 10,932 type appraisals from 1988 through 1994 from herds with > or = 40 appraisals. Heritabilities were estimated as 0.27 for final score, 0.52 for stature, 0.29 for strength, 0.24 for dairyness, 0.38 for teat diameter, 0...
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 1988
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(88)79907-5