Effect of heat stress and feeding management on growth and physiological responses of finishing pigs

National audience; The objective of the study was to determine whether heat stress (HS) effects in pigs were caused directly by heat exposure (regardless of feeding level and pattern) or indirectly due to the reduction of feed intake, and to determine if splitting heat increments via increasing feeding frequency can improve pig response to HS. A total of 48 female pigs (66.1 ± 1.7 kg) were allotted to 4 groups in 3 replicates. After 7 d in thermoneutral conditions (TN; 22°C; P1), pigs were placed in either TN or HS (32°C) conditions for 20 d (P2). The diet was provided either ad libitum (AL; 2 distributions/d) or pair-fed (PF8; 8 distributions/d) using HS-AL pigs as the reference group. Thus, the 4 experimental groups were TN-AL, HS-AL, TN-PF8, and HS-PF8. Daily ration of PF8 pigs was distributed at every 90-min intervals from 09h00 to 19h30. Data was analyzed using the PROC MIXED procedure with replicate (n=3), experimental group (n=4), and their interactions as fixed effects and the REPEATED statement was used to for repeated measures data. Pigs had similar ADFI during P1 (P>0.05), while HS-AL and PF8 pigs had lower ADFI (-19%), ADG (-25%), and final BW (-6.1 kg) than TN-AL pigs (P0.05). Muscle temperature (Tmuscle) variation depended on feeding and physical activity for TN pigs while Tmuscle gradually increased throughout the day for HS pigs. Increase in Tmuscle for each meal was lower in HS-PF8 than TN-PF8 (P