ANABOLICOS EN BOVINOS PDF

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Climatic factors affecting cattle performance in dairy and beef farms. The effect of climate on dairy and beef cattle is variable and complex because it affects the environment in which the animals are raised and reproduced.

Its influence on animal welfare and production have been recognized and studied since 's. The animals cope with these adverse conditions of climate by altering physiological and behavioral mechanisms in order to maintain their body temperature within a normal range.

As a result it is possible to observe changes in the food intake, behavior and productivity. These changes are magnified under extreme conditions of heat or cold, implying drastic reductions in the indices of production, such as average daily gain and daily milk production.

Most of the research conducted in this area has been done mainly in controlled environmental chambers, with emphasis on the animal response and its productivity. Currently, the major scientific focus is on the development of thermal stress indices as practical tools for cattle handling under unfavorable environmental conditions. The objectives of this review are to describe and discuss the most important climatic factors affecting cattle performance as well as the major mitigation alternatives.

It also presents a brief overview of the research carried out in Chile and possible lines of research in this field. Key words: stress, beef and dairy cattle, animal welfare, climatic factors. El efecto del clima en el ganado bovino es variable y complejo, ya que condiciona el medioambiente en el que los animales viven y se reproducen.

Como consecuencia, es posible observar alteraciones en el consumo de alimento, comportamiento y productividad. Temperatura ambiental. Diversos estudios realizados para determinar el consumo de agua en ganado bovino durante el verano demuestran que la temperatura tiene un importante rol.

Humedad relativa. Velocidad del viento. La importancia de la velocidad del viento fue realzada por Mader y col , quienes la incluyeron como uno de los factores de ajuste del THI. Esto fue corroborado por Brown-Brandl y col b evaluando vaquillas en engorda de cuatro razas. Cuando esto ocurre el exceso de calor es acumulado en el cuerpo resultando en un incremento en la temperatura corporal Brosh y col La temperatura corporal sigue patrones diurnos y estacionales.

Sin embargo, aun cuando la temperatura corporal tiende a seguir las fluctuaciones estacionales, existen diferencias en los patrones diurnos para el invierno y el verano Bianca , Davis y col , Collier y col , Mader y Kreikemeier Cambios hormonales. Cambios de comportamiento. Por otra parte, aumenta el tiempo dedicado a beber agua y el que permanecen de pie cerca de los bebederos.

La capacidad del ganado para enfrenar condiciones adversas de clima es variable, influyendo la especie, raza, edad, color del pelaje y piel, largo del pelaje y plano nutritional.

Este tipo de planes debe incluir a lo menos algunos de los siguientes aspectos de manejo:. Sin embargo, no todos los informes indican respuestas positivas al uso de sombra, existiendo muchos resultados inconsistentes. La estructura que provee sombra debe considerar una superficie de 1,85 a 3,70 m 2 por animal y estar ubicada a una altura de entre 2,5 y 4,0 m, ya que se debe considerar espacio suficiente para el movimiento del aire bajo la sombra.

Los autores concluyeron que las temperaturas ambientales de los meses de verano afectaron la temperatura rectal de los animales que permanecieron expuestos al sol.

Finalmente, Olivares y Caro evaluaron el efecto de la presencia de sombra en el consumo de agua y ganancia de peso de ovinos en pastoreo. Aun cuando el estudio corresponde a otra especie, se menciona para reflejar la escasez de publicaciones en torno al tema en Chile. Project: Hair coat effects on heat stress induced by toxic endophyte-infected tall fescue www.

J Anim Sci 41, Ames D, LW Insley. Windchill effect for cattle and sheep. J Anim Sci 40, Ames D. Thermal environment affects production efficiency of livestock. BioScience 30, Glossary of meteorology.

Environmental effects on pregnancy rate in beef cattle. J Anim Sci 84, Arias RA. Environmental factors affecting daily water intake on cattle finished in feedlots. Heat transfer properties of dry and wet furs of dairy cows. Trans Am Soc Agric Eng 34, Bakken GS.

A heat transfer analysis of animals: Unifying concepts and the application of metabolism chamber data to field ecology. J Theor Biol 60, Balling RC Jr. An assessment of the impact of weather conditions on feedlot cattle performance. Center for Agricultural Meteorology and Climatology. CAMaC Progress report Weight gain and mortality in feedlot cattle as influenced by weather conditions: Refinement and verification of statistical models.

Effects of warm climates on milk yield and composition short term effects. In: Smith AJ ed. Milk Production in Developing Countries. University of Edinburgh, Scotland. Potential nutritional strategies for intensively managed cattle during thermal stress.

J Anim Sci 62, Berman A. Estimates of heat stress relief needs for Holstein dairy cows. J Anim Sci 83, Dairy shelter design based on milk production decline as affected by temperature and humidity. Trans ASAE 7, Bianca W. In: Hafez ES ed. Adaptation of Domestic Animals. Water consumption, air and water temperature issues related to portable water systems for grazing cattle. Chicago, Illinois, USA. Seasonal environment, performance and energy metabolism of feedlot cattle in northern Colorado.

Blackshaw J, AW Blackshaw. Heat stress in cattle and the effect of shade on production and behaviour: a review. Aust J Exp Agric 34, Comparative effects of mud, wind and rain on beef cattle performance. Broom DM. Animal welfare: Concepts and measurement. J Anim Sci 69, Effects of solar radiation, dietary energy, and time of feeding on thermo-regulatory responses and energy balance in cattle.

J Anim Sci 76, Indicators of heat stress in shaded and non-shaded feedlot cattle. Paper number Dynamic response indicators of heat stress in shaded and non-shaded feedlot cattle, Part 1: Analyses of indicators. Biosystems Engineering 90, Analyses of thermoregulatory responses of feeder cattle exposed to simulated heat waves. Int J Biometeorol 49, Heat stress risk factors of feedlot heifers. Livest Sci , Comparison of heat tolerance of feedlot heifers of different breeds.

Black globe-humidity index BGHI as a comfort equation for dairy cows. Trans Am Soc Agric Eng 24, An introduction to environmental biophysics. Breed affects thermoregulation and epithelial morphology in imported and native cattle subjected to heat stress. J Anim Sci 73, Cortisol turnover in heat-stressed cows.

J Anim Sci 35, A seven year study of winter performance of feedlot steers in western Canada. Christopherson RJ.

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