Comportamento e termorregulação de vacas leiteiras em sistema de confinamento compost barn

Abstract

The observation of thermoregulatory and behavioral variables are indicators to infer the level of welfare of animals. Thus, studies that seek to evaluate and minimize the effects of climate on animal production have intensified, especially in confinement systems for dairy cows. However, for the containment system compost barn, information related to thermal comfort and behavior are still scarce, especially in subtropical climates. In this sense, the aim of the present study was to evaluate the thermoregulation and the behavior of dairy cows in different lactation orders and times of the day, kept in compost barn confinement system. The study was conducted on a dairy farm in the municipality of Two Neighbors, between September 2015 and February 2016. The treatments were two lactation orders (primiparous and multiparous) and hours of the day (08 to 17 hours). Two groups were formed six primiparous cows and multiparous six, distributed at random. The evaluation of diurnal behavior was performed by focal method, duration of 10 minutes and 30 minute interval between observations. To obtain the thermoregulation data were measured surface temperature of the animals and respiratory frequency. Climate variables were superficial and internal temperature of the bed, dry bulb temperature, relative humidity and wind speed, which were measured 3 in 3 hours. For the ambient thermal variables descriptive statistics were performed. Thermoregulatory variables were analyzed in the Tukey test at 5% significance. The behavior data were analyzed using statistical software via Bayesian inference R. The temperatures and relative humidity were found above the comfort range of from 12 hours. The surface temperature accompanied the increase in the ambient temperature and the internal temperature of the bed remained below the values recommended. The respiratory rate and the average surface temperature were higher for multiparous over primiparous, with maximum values found from the 12 hours. The food intake activities, lying ruminating and lying idle were observed most likely in the morning. In the afternoon there was a higher occurrence of rumination and idle standing and water intake. Multiparous starting the 13 hours had more social interactions, relative to primiparous. It is concluded that the environmental conditions of the compost barn from the 12 hours were above the comfort range and these influenced the behavior of cows. Thus, there was increased activity gasp over the hours and the activity of pushing was different between multiparous and primiparous, in the early hours and the hours passed.