INFLUENCE OF MICROCLIMATIC CONDITIONS ON THE DAILY PRODUCTION OF DAIRY COWS

The aim of this paper was to determine the microclimatic conditions (ambient temperature and relative humidity) in dairy farm, as well as to evaluate the effect and significance of temperature - humidity index (THI) values on the daily milk yield. The observation of microclimatic parameters was conducted in the period from 9.03.2012 to 6.05.2012. The study included 136 Holstein Friesian cows. The estimation of the effect of THI on daily production of dairy cows was defined by applying fixed-effect statistical model. Average ambient temperature during measuring months amounted to 15.6°C (ranging from 7.2° C to 24.6°C), while the average value of relative humidity was 56.33% (ranging from 40.30% to 81.80%). During the study, the mean value of THI was 58.93 (ranging from 47.08 to 70.13) and didn't exceed the critical comfort level of 72. All tested fixed-factors were statistically affected the daily milk yield (p <0.01). For each unit of increase in the value of the THI, the amount of milk decreased by 0.05344 kg. This confirmed the importance of regular recording of THI values and microclimatic conditions as a unique indicator of thermal stress in dairy farm.