Genetic evaluation for length of productive life of Holstein cattle in Germany
1999; Interbull Centre; Issue: 21 Linguagem: Inglês
ISSN
1011-6079
Autores Tópico(s)Effects of Environmental Stressors on Livestock
ResumoSince 1996, genetic evaluation of length of productive life of Black-and-White and Red-and-White Holstein dairy cows is carried out for West Germany. The SURVIVAL KIT package was applied for the first time in 1998 on data of all German HF-cows (Black & White and Red & White). Length of productive life is modelled with a Weibull model considering year-season within herd, lactation number * stage, relative milk yield within herd * year-season, relative change of herd size within year and a combined random genetic effect of sire and maternal grandsire of the cow. Sire solutions are standardized to a mean of 100 and a genetic standard deviation of 12, relative risks and an approximation of the breeding value expressed in days are also published. Solutions of fixed effects were plausible but averages of sire solutions differed among regions. Therefore a test-run was made in which interactions of region with lactation number * stage and with relative milk yield within herd * year-season were modelled. Solutions of the fixed effects showed that relative milk yield within herd * year-season should be considered in interaction with region.
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