Effect of black globe, dry bulb temperatures and relative humidity in cows housed in free-stall under tropical conditions

摘要

Dairy cows exposition to an adequate environment may lead to a good result in the milk production, for permitting a better use of cooling equipments and reducing the thermal stress in the animals, as well as improving level of productivity. This research work evaluated the effect of environmental dry bulb and black globe temperatures in dairy cows lodged in a free-stall building, separated in two groups: the most productive ones with milk yield above 29 kg/day and the less productive, with milk yield below 14 kg/day. Results showed the effect of the environmental variables and the temperature and humidity index in the decrease in milk yield. No high correlation was found between the index and the milk yield.