Effects of air temperature on physiology and productive performance of pigs during growing and finishing phases

Thirty-six castrated male pigs were used to determine the influence of thermal environment and reduction of consumption on performance and carcass composition. Animals were housed in two climate chambers. In one, animals were in thermal comfort (TN) (22 °C), and in the other, pigs were under heat stress (HS) (34 °C). Animals were distributed in a randomized block design, making three treatments (TN, HS and animals in thermal comfort with food consumption paired with that observed in HS (PFTN)), with six replicates and two animals per experimental unit. Data were obtained on performance and carcass composition. The weight gains of HS and PFTN animals were reduced by 40.5% and 34.7%, respectively, reflecting a reduction of 13.2% in the final weight of PFTN animals. Triiodothyronine concentration was not affected by heat, but there was an increase in lymphocyte numbers in PFTN animals. The HS and PFTN animals showed lower hot carcass weight. However, there were no effects on hot carcass yield and relative weights of heart, lung and spleen. Heat stress compromised performance. The negative effects of high temperature on pigs include reduction in feed intake and changes in physiology.Keywords: Environment, heat stress, pair feed, pig growth, pig productio

O estresse térmico agudo compromete a fisiologia dos suínos em crescimento

Foram utilizados 24 suínos machos castrados com o objetivo de determinar o efeito da temperatura ambiente sobre suas respostas termorreguladoras durante o estresse agudo por calor durante 48 horas. Os animais foram alojados em duas câmaras climatizadas com controle de temperatura, umidade e ventilação. Em uma das câmaras, os animais estavam em conforto térmico para a categoria (22ºC) e em outra, em estresse por calor (34ºC). Em cada câmara foram alojados 12 suínos, sendo a parcela experimental representada por dois animais na baia, totalizando seis repetições. As condições ambientais das câmaras climáticas e os parâmetros fisiológicos de frequência respiratória, temperatura retal e superficial foram monitoradas no início e a cada 12 horas durante o período experimental. No período observado, suínos em crescimento apresentaram respostas termorregulatórias efetivas a partir de 12 horas de exposição ao estresse agudo de calor (34°C)