Abstract
Cattle show a high sensitivity to changeability of microclimate conditions and heat stress that causes changes in the welfare and behaviour of cows. The presented study aimed at determining the relationship between the temperature humidity index (THI) value during the summer period and daily behaviour of dairy cows, including eligibility of lying boxes. All these aspects were measured under real production conditions. The investigated area, where microclimate conditions measurements were conducted, was a free-stall barn with single and double boxes, with manure and feeding alleys, housing 40 Holstein-Friesian cows. Observations were made on the behaviour of the cows based on a preference test concerning their choice of the best areas with respect to three ranges of THI values: neutral (N), warm (W) and hot (H). During the warm and hot period the research demonstrated a positive correlation between the level of THI and the share of standing cows (in period W - P<0.03 and H - P<0.008), and an inversely proportional one between the level of THI with participation of lying down cows (periods: W - P<0.06; H - P<0.004) and the length of their laying bouts in double boxes. The double boxes area was predominantly occupied, whereas single boxes area was the least often used. The occupation of manure alley areas was positively correlated with the level of THI.