THE EFFECT OF MILD TEMPERATURE STRESS ON THE OVARIAN ACTIVITY IN COWS

The aim of this study was to evaluate the effect of mild temperature stress on ovarian activity (corpus luteum count; transferable embryos; morulae and blastocysts) in cows. The evaluation included 54 Holstein cows superovulated and flushed at one farm in the Czech Republic in three different temperature periods in flushing day (mild hot season THI = 75.66; season with optimal temperature THI = 68.85; season with lower temperature THI = 45.56). The data were analysed using the PROC GEM of Statistica (R). The statistical model included the effect of season and other factors (age; condition; breeding value) on the studied reproduction traits. The results showed significantly higher ovarian activity in the cooler period of the year than in periods of mild temperature stress. There was also a non-significantly better reproduction result in younger animals under optimal condition.