Fecha/hora: 14/06/2024 04:55:24

Biblioteca(s): 	INIA Las Brujas.	
Fecha corriente: 	21/02/2014	
Fecha de la última actualización: 	18/06/2019	
Autoria: 	SÁNCHEZ, J.P.; MISZTAL, I.; AGUILAR, I.; ZUMBACH, B.; REKAYA, R.	
Afiliación: 	J. P. SÁNCHEZ, Departamento de Producción animal, Universidad de León, Spain; I. MISZTAL, Animal and Dairy Science Department, University of Georgia, United States; IGNACIO AGUILAR GARCIA, INIA (Instituto Nacional de Investigación Agropecuaria), Uruguay; B. ZUMBACH, Norsvin, Norway; R. REKAYA, Animal and Dairy Science Department, University of Georgia, United States.	
Título: 	Genetic determination of the onset of heat stress on daily milk production in the US Holstein cattle.	
Año de publicación: 	2009	
Fuente/Imprenta: 	Journal of Dairy Science, 2009, 92 (8): 4035-4045. OPEN ACCESS.	
ISSN: 	0022-0302	
DOI: 	10.3168/jds.2008-1626	
Idioma: 	Inglés	
Notas: 	Article history:  Received August 12, 2008. // Accepted March 18, 2009.	
Contenido: 	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 envi-ronmental 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. 
© american Dairy Science association, 2009.	
Palabras-Clave: 	GENETIC VARIABILITY; HEAT STRESS; HOLSTEIN; MILK YIELD.	
Thesagro: 	LECHERÍA; VARIABILIDAD GENETICA.	
Categoría del tema: 	--	
URL: 	http://www.ainfo.inia.uy/digital/bitstream/item/12194/1/1-s2.0-S0022030209707271-main.pdf	
Registro original: 	INIA Las Brujas (LB)	
Ejemplares: 	LB - (12828-1) - PXI - AP - DD - PP/JR. DAIRY SCIENCE/2009 -  -  - DIS