Determination of potential risk of heat stress of cattle in four locations of Central and Southern Chile
Determination of potential risk of heat stress of cattle in four locations of Central and Southern Chile
Authors
Arias Inostroza, Rodrigo
Mader, Terry
Mader, Terry
Authors
Date
2011-06-06
Datos de publicación:
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Abstract
Datos climáticos del periodo diciembre a febrero de los años 1999 al 2007 provenientes de estaciones meteorológicas situadas en Curicó, Chillán,
Temuco y Osorno fueron utilizados para calcular un índice temperatura-humedad ajustado por el efecto del viento y de la radiación (THIadj-max). Las
variables climáticas utilizadas para calcular este índice incluyeron: velocidad del viento, temperatura máxima del aire, humedad relativa y un valor
estimado de la radiación solar. Cuando los valores de THIadj-max fueron superiores a 75, estos días fueron considerados como indicadores de “alerta” y
riesgo potencial de estrés térmico en el ganado. Adicionalmente, el impacto en la producción animal fue estimado sobre la base de pérdidas potenciales de
producción de leche para cada localidad, utilizando dos ecuaciones para su estimación. Las localidades de la región central, Curicó y Chillán, presentaron
valores promedios de THIadj-max similares (79,4 y 79,1, respectivamente), pero ambos superiores a las de la región sur (Temuco y Osorno 77,1 y 68,1,
respectivamente; P < 0,05). La probabilidad de días con THIadj-max > 75 fue mayor en la región central. Asimismo, la producción de leche mostró un
mayor potencial de pérdidas en las regiones centrales de Chile (1,5 a 4,3 y 1,2 a 3,6 L*vaca-1*d-1 para Curicó y Chillán, respectivamente). Por otra parte,
las regiones del sur, Temuco y Osorno, presentaron menores pérdidas potenciales (0,9 a 2,6 y 0,1 a 0,6 L*vaca-1*d-1, respectivamente). En conclusión,
el riesgo potencial de estrés térmico para el ganado bovino es mayor en Curicó y Chillán, es moderado en Temuco, y es mínimo en Osorno. Finalmente,
la cuantificación del impacto directo que tiene el clima sobre la productividad y el bienestar de los bovinos en Chile necesita ser estudiada.
Meteorological data from December to January of years 1999 to 2007 from weather stations located in four localities in Chile (Curicó, Chillán, Temuco and Osorno) were used to calculate the adjusted temperature-humidity index (THIadj-max). Climate variables used to calculate the index were: wind speed, air temperature, relative humidity and an estimated value of solar radiation. When the values of THIadj-max were greater than 75, those days were considered as alert and as potential risk of heat stress in cattle. Additionally, the impact of climate on animal production was assessed by means of potential losses in milk production for each locality estimated by two equations. The localities of Curicó and Chillán presented similar values of THIadj-max (79.4 and 79.1, respectively), and both were higher than those for Temuco and Osorno (77.1 and 68.1, respectively, P < 0.05). The probability of days with mean THIadj-max > 75 was greater in the Central region. In addition, the estimated mean milk production loss was greater in the Central regions (1.5 to 4.3 and 1.2 to 3.1 L*cow-1*d-1 for Curicó and Chillán, respectively). Conversely, the Southern regions, Temuco and Osorno, presented lower potential losses with 0.9 to 2.6 and 0.1 to 0.6 L*cow-1*d-1, respectively. In conclusion, the potential risk of heat stress of cattle seems greater in Curicó and Chillán, moderate in Temuco and minimum in Osorno. Additional research is needed in the order to quantify the impacts of environmental conditions in productivity and welfare of cattle in Chile.
Meteorological data from December to January of years 1999 to 2007 from weather stations located in four localities in Chile (Curicó, Chillán, Temuco and Osorno) were used to calculate the adjusted temperature-humidity index (THIadj-max). Climate variables used to calculate the index were: wind speed, air temperature, relative humidity and an estimated value of solar radiation. When the values of THIadj-max were greater than 75, those days were considered as alert and as potential risk of heat stress in cattle. Additionally, the impact of climate on animal production was assessed by means of potential losses in milk production for each locality estimated by two equations. The localities of Curicó and Chillán presented similar values of THIadj-max (79.4 and 79.1, respectively), and both were higher than those for Temuco and Osorno (77.1 and 68.1, respectively, P < 0.05). The probability of days with mean THIadj-max > 75 was greater in the Central region. In addition, the estimated mean milk production loss was greater in the Central regions (1.5 to 4.3 and 1.2 to 3.1 L*cow-1*d-1 for Curicó and Chillán, respectively). Conversely, the Southern regions, Temuco and Osorno, presented lower potential losses with 0.9 to 2.6 and 0.1 to 0.6 L*cow-1*d-1, respectively. In conclusion, the potential risk of heat stress of cattle seems greater in Curicó and Chillán, moderate in Temuco and minimum in Osorno. Additional research is needed in the order to quantify the impacts of environmental conditions in productivity and welfare of cattle in Chile.