The Effect of Environmental Cooling Rate and Temperature-Humidity Index on the Milk Yield of Holstein Cattle on a Specific Farm

The objective of this work was to assess the effect of environmental cooling rate and temperature-humidity index on the milk yield of Holstein cattle on a specific farm. The experiment took place at a university farm (South Moravia) in the summer of 2017 and lasted over one month. The cows with the highest production have been chosen for this study since these cows have been suspected to be affected by heat stress more than the low-producing ones. The Environmental cooling rate (ECR) was measured by Hill´s thermometer and later calculated according to a formula. The temperature-humidity index (THI) was calculated from temperature and humidity data obtained by a data logger placed in the stable. Milk yield data were obtained directly from the milk parlour. The results show that the ECR is in a weak positive relationship (r= 0.07) with the milk yield. On the contrary, the THI showed moderate negative relation to the milk yield (r= -0.14)