期刊
JOURNAL OF ANIMAL SCIENCE
卷 96, 期 3, 页码 941-949出版社
OXFORD UNIV PRESS INC
DOI: 10.1093/jas/skx036
关键词
gilts; heat tolerance; thermoregulation
资金
- Iowa Pork Producers Association
- National Pork Board
- Agriculture and Food Research Initiative Competitive from the USDA National Institute of Food and Agriculture [2011-67003-30007]
Identifying traits associated with susceptibility or tolerance to heat stress (HS) is a prerequisite for developing strategies to improve efficient pork production during the summer months. Study objectives were to determine the relationship between the thermoregulatory and production responses to acute HS in pigs. Prepubertal gilts (n = 235; 77.9 +/- 1.2 kg BW) were exposed to a thermoneutral (TN) period (P1, 24 h; 21.9 +/- 0.5 degrees C, 62 +/- 13% RH; fed ad libitum) followed immediately by a subsequent acute HS period (P2, 24 h; 29.7 +/- 1.3 degrees C, 49 +/- 8% RH; fed ad libitum). Rectal temperature (T-R), skin temperature (T-S), and respiration rate (RR) were monitored and BW and feed intake (FI) were determined. All pigs had increased T-R, T-S, and RR (0.80 degrees C, 5.65 degrees C, and 61.2 bpm, respectively; P < 0.01) and decreased FI and BW (29% and 1.10 kg, respectively; P < 0.01) during P2 compared to P1. Interestingly, body temperature indices did not explain variation in FI during P2 (R-2 <= 0.02). Further, the percent change in BW during P2 was only marginally explained by each body temperature index (R-2 <= 0.06) or percent change in FI (R-2 = 0.14). During HS, T-R was strongly correlated with P1 T-R (r = 0.72, P < 0.01), indicating a pig's body temperature during TN conditions predicts the severity of hyperthermia during HS. Additionally, the change in T-R (Delta T-R, HS T-R - TN T-R) was larger in pigs retrospectively classified as susceptible (SUS) as compared to tolerant (TOL) pigs (1.05 vs. 0.51 degrees C, respectively; P < 0.01). In summary, thermoregulatory responses and production variables during acute HS are only marginally related. Further, changes in BW and FI were unexpectedly poorly correlated during acute HS (r = 0.34; P < 0.01). Collectively, suboptimal growth is largely independent on the thermoregulatory response and hypophagia during acute HS. Consequently, incorporating solely body temperature indices into a genetic index is likely insufficient for substantial progress in selecting HS tolerant pigs.
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