Climatização da sala de espera para vacas criadas a pasto sem sombreamento

The aim of this study was to evaluate different climatization systems in the holding-pen and their effect on physiological variables and Holstein milk production raised on paddock without shade access. The treatments were shade (Control - CT), forced ventilation (VT) + nebulization (VN) during 30 minutes before milking. Twelve multiparous Holstein cows were used in a replicated 3x3 Latin square, with 18-d periods comprised of five days for adaptation followed by three-day sample. Dry bulb temperature (DBT), black globe temperature (BGT), relative humidity (RH), wind speed (WV), Black globe-humidity index (BGHI), rectal temperature (RT), respiratory rate (RR), surface temperatures of head, back, leg and udder and milk production were analysed. After 30 minutes in the holding-pen, treatment VN showed lower microclimate variables TBS, TGN and ITGU. Treatment VN decreased (p 0.05) between CT and VT treatments. Cows receiving VN treatment had 0.47 kg/cow/day greater (p<0.02) milk yield compared to those in which CT was applied. The use of forced ventilation plus nebulization at holding-pen improved microclimate conditions, enhanced thermal comfort and increased milk yield of Holstein grazing pasture without shade access.