Manejo reprodutivo de vacas sob estresse calórico

• Autor(a) principal: Vasconcelos, José Luiz Moraes [UNESP]
• Data de Publicação: 2011
• Outros Autores: Demétrio, Daniela Garcia Borges [UNESP]
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.revista.sbz.org.br/artigo/index.php?artigo=66295; http://hdl.handle.net/11449/141115
• topic: Conception; Dairy cows; Heat stress; Pregnancy; Concepção; Estresse calórico; Gado de leite; Prenhez

Heat stress negatively affects the productivity of lactating dairy cows. Lactating dairy cows are more sensitive to heat stress as milk yield increases, because increases metabolic heat production. Selection for milk yield reduces heat tolerance and could increase the susceptibility to heat stress decreasing milk production and pregnancy during the summer. The objective of this review is to discuss how heat stress affects pregnancy, and some strategies to decrease this effect. In a study in Brazil within 33 farms in the southeast, more than 60% of cows have rectal temperature >39.1ºC between 2 to 8PM. In another study rectal temperature at day 7 affected negatively pregnancy rates after artificial insemination or embryo transfer and was detected a tendency of increase in embryonic losses between 25 and 39 days within higher rectal temperature at day 7. Also were detected that high producer cows have lower pregnancy only if also have increase in rectal body temperature. Heat stress is a problem in Brazil, we need to evaluate the rectal temperature at afternoon to determine if cows are in heat stress (>39.1°C) and utilize strategies to minimize negative impact on the profitability of lactating dairy cows.