Effects on fetal and maternal body temperatures of exposure of pregnant ewes to heat, cold, and exercise.
We exposed Dorper-cross ewes at approximately 120-135 days of gestation to a hot (40 degrees C, 60% relative humidity) and a cold (4 degrees C, 90% relative humidity) environment and to treadmill exercise (2.1 km/h, 5 degrees gradient) and measured fetal lamb and ewe body temperatures using previously implanted abdominal radiotelemeters. When ewes were exposed to 2 h of heat or 30 min of exercise, body temperature rose less in the fetus than in the mother, such that the difference between fetal and maternal body temperature, on average 0.6 degrees C before the thermal stress, fell significantly by 0.54 +/- 0.06 degrees C (SE, n = 8) during heat exposure and by 0.21 +/- 0.08 degrees C (n = 7) during exercise. During 6 h of maternal exposure to cold, temperature fell significantly less in the fetus than in the ewe, and the difference between fetal and maternal body temperature rose to 1.16 +/- 0.26 degrees C (n = 9). Thermoregulatory strategies used by the pregnant ewe for thermoregulation during heat or cold exposure appear to protect the fetus from changes in its thermal environment.
Laburn
Helen P
HP
Brain Function Research Unit, Department of Physiology, University of the Witwatersrand, Parktown 2193, South Africa. 057Helen@chiron.wits.ac.za
Faurie
Alida
A
Goelst
Kathleen
K
Mitchell
Duncan
D
D000818:Animals; D001831:Body Temperature; D003080:Cold Temperature; D005260:Female; D005333:Fetus / Q000502:physiology*; D006358:Hot Temperature; D009043:Motor Activity / Q000502:physiology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012756:Sheep / Q000196:embryology; D013686:Telemetry