The Thai Journal of Veterinary Medicine


The aim of this study was to determine the effects of temperature and humidity on the conception rate of Holstein crossbred dairy cows in smallholder farms in Chiang Mai, Thailand. 7,312 pregnancy diagnosis examinations on 3,166 dairy cows in 510 herds and artificially inseminated, were collected by Chiang Mai AI Research and Biotechnology Center. The monthly average weather data, including minimum and maximum of both temperature and humidity, were obtained from the Thai Meteorological Department for the months January 2001 to December 2002. The relationship between temperature, humidity and conception rates were analyses by using a generalized estimation equation. For univariable analysis, all weather data were negatively related to conception rates (p < 0.05). For multivariable analysis, the final model consisted of monthly average minimum temperature (p < 0.01) and monthly average maximum humidity (p = 0.1). This study indicated that an increase in the minimum temperature and maximum humidity resulted in decreased conception rates in Holstein crossbred dairy cows.

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