文章基本信息

标题：Estimation of genetic parameters and environmental effects on somatic cell count in Simmental and Holstein breeds
本地全文：下载
作者：Ivkić, Zdenko ; Špehar, Marija ; Bulić, Vesna 等
期刊名称：Mljekarstvo
印刷版ISSN：0026-704X
电子版ISSN：1846-4025
出版年度：2012
卷号：62
期号：2
页码：143-150
出版社：Hrvatska Mljekarska Udruga
摘要：The objective of this study was to estimate genetic parameters and environmental effects on somatic cell count in Croatian dairy cows. Data consisted of 861,417 test-day records for Simmental and 656,272 for Holstein cows. For Simmental breed, number of animals in pedigree was 123,199, while pedigree file for Holstein breed included 94,294 animals. A single-trait repeatability fixed regression test-day model was used to estimate genetic parameters. Fixed effects in the model were parity and calving season. Days in milk was fitted using Ali-Schaeffer lactation curve nested within parity. Age at first calving was modelled as quadratic regression. Direct additive genetic effect, herd, herd-test-date, and permanent environmental effect of cow within parity were included in the model as random effects. Variance components were estimated using Residual Maximum Likelihood method as implemented in the VCE-6 program. Estimated heritabilities were 0.21 for Simmental and 0.15 for the Holstein breed. Permanent environmental effect explained 19 % of phenotypic variation in Simmental and 20 % in Holstein breed. Herd and herd-test-date accounted for another 9 % and 5 % of variability for Simmental breed. The effects of herd and herd-test-date explained 10 % and 5 % of phenotypic variance in Holstein breed.
关键词：somatic cell count; Simmental and Holstein breed; environmental effects; genetic parameters