tokens: 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 .