evaporative cooling for lactating sows under high ambient temperature

Two experiments were conducted to evaluate the evaporative cooling of the air at farrowing on the performance of lactating sows under high environmental temperature conditions in the Central West region of Brazil. One hundred and forty-four lactating sows - 46 of first and second farrowing (experiment I) and 98 from the third to eighth farrowing (experiment II) - were used. Sows were distributed in experimental design of randomized blocks consisting of two rooms (with air cooling and control), with the sow as the experimental unit. The average duration of lactation was 21 days. Sows were fed ad libitum with the same lactation diet. In experiment I, the air cooling increased the daily feed intake, reduced the total and percent weight loss, increased the weight of the piglets and litters at weaning and improved the daily milk production of sows. However, the air cooling did not affect the weight of the sows or the number of piglets at weaning. In experiment II the air cooling increased the daily feed intake of the sows, reduced the total and percent weight loss, increased the weight and the weight gain of the piglets and litters and improved the daily milk production of the sows. Air cooling enables the increase of the daily feed intake and, therefore, of nutrients by the sows, with consequent reduction of mobilization of body reserves and the increase in the milk production and in the weight of piglets and litters at weaning, regardless the farrowing order of the sow.