The aim of this study was to evaluate the effects of climatization (ventilation or ventilation plus sprinkler) inside a holding pen in a milking parlor on environmental and physiological parameters. The experiment was conducted from August to October during 90 consecutive days. Twenty-one lactating dairy cows with an average milk yield of 21kg.d-1 were randomly allocated in three treatments. The treatments were: holding pen without cooling (control); holding pen with ventilation (V) and holding pen with ventilation plus sprinkler (VS). The physiological parameters measured were respiratory rate (RR), body temperature (BT) and skin temperature (head, flank and mammary gland). These measurements were taken before and after each treatment. The data on the environmental parameters dry bulb temperature (DBT), black globe temperature (BGT) and relative humidity (RH) were collected both from each treatment session and from a meteorological station at a nearby site three times a day. Results showed that VS reduced DBT (6.4°C) and BGT (6.5°C); and increased the RH. Both V and VS reduced significantly respiratory rate. The skin temperature, with VS showed a decrease of 4.2°C for the head and 2.8°C for the flank. Hence, VS improved the environmental condition and physiological responses and increased heat losses of the dairy cows.
heat stress; physiological responses; evaporative cooling
