Heat stress of dairy cows subjected to different cooling systems

This paper presents the results of a research study which had the objective of investigating the effect of a sprinkler system coupled with forced ventilation on the heat stress of dairy cows bred in a free stall barn without paddock. To this aim, an experiment was carried out inside a free-stall dairy house equipped with two different cooling systems: a fogging system associated with forced ventilation in the resting area and a sprinkler system associated with forced ventilation in the feeding alley. The experiment regarded two adjacent boxes of the barn and was constituted by three different trials carried out in the following periods: 27th June – 7th July (P1), 25th July – 4th August (P2), 24th August – 3rd September (P3). The experimental protocol of each trial required that in one box the two cooling systems were always activated following an established timetable, whereas in the other box the sprinkler system associated with forced ventilation was always deactivated. Climatic parameters were measured inside each box of the barn and outside. Then, THI index was calculated. Rectal temperature and respiration rate of a sample of dairy cows were monitored each day during the three periods considered (P1, P2 and P3). During the experiment, the cows of each box were subjected to mild or moderate heat stress. Although the sprinklers do not influence the microclimatic conditions, their use contributed to relieve heat stress as attested by a worsening of the physiological conditions of the cows that were bred in the box with the sprinkler system deactivated.