Comparison of different cooling systems in a dairy house in Mediterranean climate.

University of Catania, Department of Agricultural and Food Science, Animal Production Division, via Valdisavoia 5, Catania, 95123, Italy *Corresponding author. E-mail: gcascone@unict.it Abstract The solutions aiming to defend cows from heat stress inside dairy houses can be classified into passive systems and active plants. Among the active plants, different systems based on ventilation coupled with sprinkling and/or direct wetting of animals were proved to be efficacy under various conditions in defending cows from heat inside dairy houses. This work shows the results of a two years trial carried out in a commercial dairy house sited in Acate (Ragusa, Italy) to compare an existing cooling system made by sprinklers and box fans placed above the cubicle area with a sprinkler and radial fan system for animal wetting installed along the feeding alley. The results show the effects of the two different cooling systems on the microclimatic conditions inside the dairy house and on the physiological response of the cows. During the trial, the main climatic parameters were measured outside and inside the barn. Thermal Humidity Index (THI) and Black Globe Humidity Index (BGHI) were calculated. Rectal temperature, respiratory rate and milk yield were measured on two 30 lactating Holstein Friesian cows. The results show that the sprinkler and radial-fan system for wetting cows, although it produced small changes in microclimatic conditions inside the barn, was more effective than the sprinkler and box-fan system. Specifically, black-globe temperatures in feeding alley obtained by the sprinkler and radial-fan system were slight lower than in the cubicle area, allowing more comfortable conditions near the rack. The positive effect of this cooling system compared to the existing one on the physiological and productive response of cows was shown by the lower mean values of rectal temperature and respiration rate and by the higher milk yield. Key words : Dairy house, heat stress, cooling systems, sprinkler and fan, animal wetting. 1. Introduction The thermal environment is one of the ambient factor that most influences the comfort of dairy cows and, consequently, the quantity and quality of milk production. This issue assumed a growing interest in the last years, as the genetic improvements shifted the thermo neutrality-zone of the cows to lower temperature, so increasing their sensitivity to heat stress (Khongdee et al., 2006; Kadzere et al, 2002). Different active systems based on ventilation coupled with cooling pads, sprinkling and/or direct wetting of animals were proved to be efficacy under various conditions in defending from heat the cows inside dairy houses. Ryan et al. (1992) found evaporative cooling more effective than spray and fan system on Holstein cows housed in hot-dry climate. Khongdee et al. (2006) obtained an increase in the milk yield using evaporative cooling also in hot-wet conditions.