Estrus-related odors in body fluids of dairy cows

Six experiments were to test for estrus-associated odors in 1) swabs of the vulva and vestibule, 2) fluids from deep in the vagina, 3) naturally voided urine, 4) urine obtained from the bladder by catheter, 5) milk, and 6) blood plasma. Tests were with dogs trained to identify vaginal fluids from estrous cows. In the tests, dogs were walked along lines of seven sample bottles consisting of samples from two estrous cows, two luteal-phase cows, one vaginal swab from estrous cows used as a standard, and two blank sample bottles. Correct responses to fluids from estrous cows averaged 97, 86, 96, 97, 99, and 94% for the six fluids listed. Incorrect responses to fluids from luteal-phase cows were 2, 1, 1, 1, 1, and 8%. Responses to blank samples were usually zero. Results indicate that odors associated with estrus are spread throughout the cow's body fluid.