Body Temperature Variations in Dairy Cattle during the Estrous Cycle and Pregnancy

Abstract

Daily body temperatures were taken vaginally in 24 cows for a total of 54 cycles. The temperatures were found to fluctuate with the estrous cycle, being lowest just before heat, high on the day of heat, low again at the time of ovulation, and high during the luteal phase of the cycle. Observations were made also on nine cows in the terminal stage of pregnancy. In these cows, a precipitous decline in body temperature indicative of the imminence of parturition was noted. In addition, preliminary experiments were conducted in which progestational steroids were administered to spayed cows. The resultant thermogenic responses suggest that endogenous progesterone elaboration is responsible for the cyclic and pregnancy body temperature variations of intact cows. Body temperature observations may provide a useful indicator of corpus luteum activity in the bovine. © 1958, American Dairy Science Association. All rights reserved.