%0 Journal Article %1 Sánchez20094035 %A Sánchez, J.P. %A Misztal, I. %A Aguilar, I. %A Zumbach, B. %A Rekaya, R. %D 2009 %J Journal of Dairy Science %K 2009 dairy_cattle heat_stress %N 8 %P 4035 - 4045 %R http://dx.doi.org/10.3168/jds.2008-1626 %T Genetic determination of the onset of heat stress on daily milk production in the US Holstein cattle %U http://www.sciencedirect.com/science/article/pii/S0022030209707271 %V 92 %X Existence of individual variation in the onset of heat stress for daily milk yield of dairy cows was assessed. Data included 353,376 test-day records of 38,383 first-parity Holsteins from a random sample of \US\ herds. Three hierarchical models were investigated. Model 1 inferred the value of a temperature-humidity index (THI) at which mean yield began to decline as well as the extent of that decline. Model 2 assumed individual variation in yield decline beyond a common ÞI\ threshold. Model 3 additionally assumed individual variation for the onset of heat stress. Deviance information criteria indicated the superiority of model 3 over model 2. For model 2, genetic correlation between milk yield in the absence of heat stress and the ÞI\ threshold for heat stress was −0.4 (0.11) marginal posterior mean (marginal posterior standard deviation). For model 3, genetic correlations were −0.53 (0.05) between milk yield and ÞI\ threshold and −0.62 (0.08) between milk yield and yield decay beyond the ÞI\ threshold. Total standard deviation (sum of additive genetic and permanent environmental standard deviations) for the ÞI\ threshold was 3.95 (0.06), and more than half of that variation had an additive genetic origin 56% (5%). Because of the high genetic correlation 0.95 (0.03) between yield decay and ÞI\ threshold with model 3, using only one of them as a selection criterion for heat tolerance would modify the other in the desired direction.

@article{Sánchez20094035, abstract = {Existence of individual variation in the onset of heat stress for daily milk yield of dairy cows was assessed. Data included 353,376 test-day records of 38,383 first-parity Holsteins from a random sample of \{US\} herds. Three hierarchical models were investigated. Model 1 inferred the value of a temperature-humidity index (THI) at which mean yield began to decline as well as the extent of that decline. Model 2 assumed individual variation in yield decline beyond a common \{THI\} threshold. Model 3 additionally assumed individual variation for the onset of heat stress. Deviance information criteria indicated the superiority of model 3 over model 2. For model 2, genetic correlation between milk yield in the absence of heat stress and the \{THI\} threshold for heat stress was −0.4 (0.11) [marginal posterior mean (marginal posterior standard deviation)]. For model 3, genetic correlations were −0.53 (0.05) between milk yield and \{THI\} threshold and −0.62 (0.08) between milk yield and yield decay beyond the \{THI\} threshold. Total standard deviation (sum of additive genetic and permanent environmental standard deviations) for the \{THI\} threshold was 3.95 (0.06), and more than half of that variation had an additive genetic origin [56% (5%)]. Because of the high genetic correlation [0.95 (0.03)] between yield decay and \{THI\} threshold with model 3, using only one of them as a selection criterion for heat tolerance would modify the other in the desired direction. }, added-at = {2016-05-18T03:46:55.000+0200}, author = {Sánchez, J.P. and Misztal, I. and Aguilar, I. and Zumbach, B. and Rekaya, R.}, biburl = {https://www.bibsonomy.org/bibtex/28a5f74bc3079e6511fcb259db143b09b/uga.abgg}, doi = {http://dx.doi.org/10.3168/jds.2008-1626}, interhash = {dcfdbd30219909900913a0c10f13b323}, intrahash = {8a5f74bc3079e6511fcb259db143b09b}, issn = {0022-0302}, journal = {Journal of Dairy Science }, keywords = {2009 dairy_cattle heat_stress}, number = 8, pages = {4035 - 4045}, timestamp = {2016-05-18T03:46:55.000+0200}, title = {Genetic determination of the onset of heat stress on daily milk production in the US Holstein cattle }, url = {http://www.sciencedirect.com/science/article/pii/S0022030209707271}, volume = 92, year = 2009 }