An improved model for the French genetic evaluation of dairy bulls on length of productive life of their daughters
| العنوان: | An improved model for the French genetic evaluation of dairy bulls on length of productive life of their daughters |
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| المؤلفون: | Vincent Ducrocq |
| المساهمون: | Station de Génétique Quantitative et Appliquée (SGQA), Institut National de la Recherche Agronomique (INRA) |
| المصدر: | 55th Annual Meeting of the European Association for Animal Production 55th Annual Meeting of the European Association for Animal Production, 2004, Bled Animal Science Animal Science, Cambridge University Press (CUP), 2005, 80, pp.249-256 |
| بيانات النشر: | Cambridge University Press (CUP), 2005. |
| سنة النشر: | 2005 |
| مصطلحات موضوعية: | PROGRES GENETIQUE, 040301 veterinary sciences, [SDV]Life Sciences [q-bio], media_common.quotation_subject, Ice calving, Biology, GENETIC EVALUATION, GENETIC TREND, 0403 veterinary science, Animal science, Genetic variation, LONGEVITY, SURVIVAL ANALYSIS, ComputingMilieux_MISCELLANEOUS, Dairy cattle, Selection (genetic algorithm), media_common, Weibull distribution, Proportional hazards model, Hazard ratio, 0402 animal and dairy science, Longevity, 04 agricultural and veterinary sciences, 040201 dairy & animal science, ANALYSE DE SURVIE, WEIBULL MODEL, Animal Science and Zoology, DAIRY CATTLE |
| الوصف: | Functional longevity of dairy cows has been routinely evaluated in France since 1997 using a survival analysis model. Recently, we proposed a genetic trend validation test that could be used before including national data in an international evaluation of bulls on longevity of their daughters. Its application to the French Holstein data revealed a large overestimation of the genetic trend. It was found that the bias is the result of a change in the baseline hazard rate over time. A new proportional hazards model is proposed which accounts for this change. In the new model, the baseline is described as a stratified, piecewise Weibull hazard function within lactation, i.e. a function of the number of days since the most recent calving. Stratification is within year and parity. Different Weibull hazard functions are used over four periods: 0 to 270 days, 271 to 380 days, 381 days to day when dried, dry period until the next calving. The non-genetic effects included in the model were slightly different from the previous one. In particular the interaction effects between the within herd-year class of production and lactation number × stage of lactation on the one hand and year-season were accounted for. The estimated genetic variance was smaller than with the old model. The new genetic trend is almost flat. An illustration of the efficiency of selection on the estimated breeding values for longevity is presented. |
| تدمد: | 1748-748X 1357-7298 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e8a5c1ea279787ef91d8be6d3dc48964Test https://doi.org/10.1079/asc41720249Test |
| حقوق: | CLOSED |
| رقم الانضمام: | edsair.doi.dedup.....e8a5c1ea279787ef91d8be6d3dc48964 |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 1748748X 13577298 |
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