title: Effects of rapid temperature fluctuations prior to breeding on reproductive efficiency in replacement gilts.
abstract: Rapidly cooling pigs after heat stress (HS) results in a pathophysiological condition, and because rapid temperature fluctuations may be associated with reduced reproductive success in sows, it lends itself to the hypothesis that these conditions may be linked. Objectives were to determine the effects of rapid cooling on thermal response and future reproductive success in pigs. Thirty-six replacement gilts (137.8±0.9kg BW) were estrus synchronized and then 14.1±0.4 d after estrus confirmation, pigs were exposed to thermoneutral conditions (TN; n=12; 19.7±0.9°C) for 6h, or HS (36.3±0.5°C) for 3h, followed by 3h of rapid cooling (HSRC; n=12; immediate TN exposure and water dousing) or gradual cooling (HSGC; n=12; gradual decrease to TN conditions) repeated over 2 d. Vaginal (TV) and gastrointestinal tract temperatures (TGI) were obtained every 15min, and blood was collected on d 1 and d 2 during the HS and recovery periods at 180 and 60min, respectively. Pigs were bred 8.3±0.8 d after thermal treatments over 2 d. Reproductive tracts were collected and total fetus number and viability were recorded 28.0±0.8 d after insemination. HS increased TVand TGI(P=0.01; 0.98°C) in HSRC and HSGC compared to TN pigs. During recovery, TVwas reduced from 15 to 105min (P=0.01; 0.33°C) in HSRC compared to HSGC pigs, but no overall differences in TGIwere detected (P<0.05; 39.67°C). Rapid cooling increased (P<0.05) TNFα compared to HSGC and TN pigs during recovery-d 1 (55.2%), HS-d 2 (35.1%), and recovery-d 2 (64.9%). Viable fetuses tended to be reduced (P=0.08; 10.5%) and moribund fetuses tended to be increased (P=0.09; 159.3%) in HSRC compared to HSGC and TN pigs. In summary, rapid cooling prior to breeding may contribute to reduced fetal viability and reproductive success in pigs.
authors.affiliation: USDA-ARS, Livestock Behavior Research Unit, 125 S. Russell St., Rm. 219C, West Lafayette, IN 47907, United States. Electronic address: Jay.Johnson@ars.usda.gov.
authors.forename: J S
authors.initials: JS
authors.lastname: Johnson
authors.affiliation: Purdue University, Department of Animal Sciences, West Lafayette, IN 47907, United States.
authors.forename: K L
authors.initials: KL
authors.lastname: Martin
authors.affiliation: University of Tennessee, Department of Animal Science, Knoxville, TN 37996, United States.
authors.forename: K G
authors.initials: KG
authors.lastname: Pohler
authors.affiliation: Purdue University, Department of Animal Sciences, West Lafayette, IN 47907, United States.
authors.forename: K R
authors.initials: KR
authors.lastname: Stewart
mesh_terms: D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation; D001947:Breeding; D003080:Cold Temperature; D058639:Cold-Shock Response; D005260:Female; D018882:Heat Stress Disorders / Q000097:blood / Q000503:physiopathology / Q000662:veterinary; D018869:Heat-Shock Response; D006358:Hot Temperature; D007333:Insulin Resistance; D008297:Male; D012098:Reproduction; D013312:Stress, Physiological; D013552:Swine / Q000097:blood / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D014409:Tumor Necrosis Factor-alpha
keywords: Breeding; Fetal viability; Pigs; Rapid cooling; Temperature fluctuations