Veterinary session

The management of problems arising due to the adverse effects of heat stress is a significant task from a veterinary point of view. As a result of climate change, the number of days above the annual heat stress limit is increasing, which can cause significant damage in the summer months. In our research, we investigated the effect of improved barn cooling (installation of efficient fans with an air speed of 1.8-2.5 m/s) on the thermal sensation of the animals and how the milk production and the behaviour of the cows change as the degree of heat stress experienced decreases. The effect of the installed fans was tested on two groups of twenty cows, of which new temperature-dependent fans were installed in the barn of the experimental group. In contrast, in the barn of the control group, the older type of fan used on the farm remained (max. 0.5-0.8 m/s airspeed). We found that during the study, the daily average THI value rose above 68 in the barns of both groups. During three of the four test occasions, the mean daily temperature exceeded 25°C; the animals were exposed to significant heat stress. The cows' body temperature in the experimental group was significantly lower with similar barn temperature and THI values. There was also a difference in the behaviour of the animals in the two groups because, in the case of more efficient ventilation, the animals spent more time taking in feed after 20 weeks of lactation, while the time spent rumination was similar to that of the control group. Presumably, due to the increased time spent eating, milk production was significantly higher in the cows of the experimental group. Another reason for higher production may be lower metabolic heat load due to lower body temperature. The results of the study showed that the higher-power fans had a positive effect on the cows' milk production and behaviour.