Premium
Estimation of genetic parameters for heat stress, including dominance gene effects, on milk yield in T hai H olstein dairy cattle
Author(s) -
Boonkum Wuttigrai,
Duangjinda Monchai
Publication year - 2015
Publication title -
animal science journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.606
H-Index - 38
eISSN - 1740-0929
pISSN - 1344-3941
DOI - 10.1111/asj.12276
Subject(s) - heritability , restricted maximum likelihood , dairy cattle , biology , zoology , additive genetic effects , heat stress , selection (genetic algorithm) , dominance (genetics) , microbiology and biotechnology , statistics , mathematics , maximum likelihood , genetics , gene , artificial intelligence , computer science
Heat stress in tropical regions is a major cause that strongly negatively affects to milk production in dairy cattle. Genetic selection for dairy heat tolerance is powerful technique to improve genetic performance. Therefore, the current study aimed to estimate genetic parameters and investigate the threshold point of heat stress for milk yield. Data included 52 701 test‐day milk yield records for the first parity from 6247 T hai H olstein dairy cattle, covering the period 1990 to 2007. The random regression test day model with EM ‐ REML was used to estimate variance components, genetic parameters and milk production loss. A decline in milk production was found when temperature and humidity index ( THI ) exceeded a threshold of 74, also it was associated with the high percentage of H olstein genetics. All variance component estimates increased with THI . The estimate of heritability of test‐day milk yield was 0.231. Dominance variance as a proportion to additive variance (0.035) indicated that non‐additive effects might not be of concern for milk genetics studies in T hai H olstein cattle. Correlations between genetic and permanent environmental effects, for regular conditions and due to heat stress, were − 0.223 and − 0.521, respectively. The heritability and genetic correlations from this study show that simultaneous selection for milk production and heat tolerance is possible.