PSII-26 Changes in growth performance, cytokine profile and eating and drinking behaviors of growing pigs subjected to an induced heat stress

Abstract

Abstract This study was conducted to determine effects of induced heat stress on growth performance, cytokine profile and eating and drinking behaviors of growing pigs. Pigs (n = 32; average BW =42.25±0.78 kg) were housed individually in thermo-neutral conditions (CON) or subjected to constant high ambient temperatures (mean 81.7°F) for 15 d (HS), followed by a 7 d recovery period (mean 68.6°F). Pig weights and feed disappearance were recorded on d 0, 8, 15 and 22 for calculations of ADG, ADFI and GF. Blood samples were taken via venipuncture on d 2, 8, 15 and 22, and serum was analyzed for cytokine profile by multiplex-ELISA. Four pigs per treatment were video-recorded on d 2, 6, 9, 16 and 21 for 2 h at 800, 1300 and 1600. Frequency and duration of eating and drinking were recorded. HS pigs had lower ADFI (1.97 kg/d) and ADG (0.91 kg/d) compared to CON pigs (2.39 and 1.11 kg/d, respectively) during wk 1. HS pigs had lower ADFI (2.24 kg/d) during the recovery period compared to CON (2.74 kg/d) pigs. During the overall trial period, HS pigs had lower ADFI (2.30 kg/d) and ADG (0.99 kg/d) compared to CON pigs (2.69 and 1.14 kg/d, respectively), however, GF for HS pigs (0.43) was not different from CON (0.42). HS pigs had increased IL1β (617 pg/mL) and IL12 (1380 pg/mL) compared to CON pigs (248 and 1127 pg/mL, respectively). IL8 was increased for CON (1340 pg/mL) compared to HS (522 pg/mL; P < 0.001). HS pigs ate less frequently in the morning (2 times/h) compared to CON pigs (4.1 times/h; time x treatment interaction, P = 0.003). Regardless of treatment, drinking frequency increased from 1600–1800 (5.7 times/h) compared to 800–1000 (2 times/h; P < 0.001). Heat stress reduces performance, increases circulating inflammatory cytokines and alters daily time of eating.