Performance of growing pigs subjected to lighting programs in climate-controlled environments

ABSTRACT The objective of this research was to evaluate the thermal comfort, physiological responses and performance of pigs in the growth phase, subjected to supplemental lighting programs in air-conditioned environments, in semiarid region of Pernambuco state, Brazil. Twenty-seven pigs (3/4 Duroc, ¼ Pietrain) were subjected to pens with no climate control, pens with forced ventilation and pens with adiabatic evaporative cooling, associated with 12 h of natural light, 12 h of natural light + 4 h of artificial light and 12 h of natural light + 6 h of artificial light. The experimental design was completely randomized, in a 3 x 3 factorial arrangement with three repetitions. Meteorological responses, physiological responses and performance variables of the animals were recorded. The evaporative cooling system attenuated the action of the stressors and ensured adequate thermal conditions for the animals. Respiratory rate and rectal temperature indicated that evaporative cooling ensured the maintenance of homeothermy. Weight gain and feed conversion were positively influenced for the animals exposed to evaporative cooling, but without significant effect of lighting programs. RESUMO O objetivo desta pesquisa foi avaliar o conforto térmico, as respostas fisiológicas e o desempenho de porcos na fase de crescimento, submetidos a programas complementares de iluminação em ambientes climatizados, na região semiárida de Pernambuco, Brasil. Vinte e sete porcos (3/4 Duroc, ¼ Pietrain) foram submetidos a baias sem ar condicionado, baias com ventilação forçada e baias com resfriamento adiabático evaporativo, associadas a 12 h de luz natural, 12 h de luz natural + 4 h de luz artificial e 12 h de luz natural + 6 h de luz artificial. O delineamento experimental foi inteiramente casualizado, em arranjo fatorial 3 x 3, com três repetições. As respostas meteorológicas, fisiológicas e variáveis de desempenho dos animais foram registradas. O sistema de resfriamento evaporativo atenuou a ação dos agentes estressores e garantiu o alojamento térmico adequado para os animais. A frequência respiratória e a temperatura retal indicaram que o resfriamento evaporativo garantiu a manutenção da homeotermia. O ganho de peso e a conversão alimentar foram influenciados positivamente para os animais expostos ao resfriamento evaporativo, no entanto, sem efeito significativo dos programas de iluminação.