Table 4-6. METHODS OF ESTROUS DETECTION IN CATTLE

Twice daily visual observations (estrous females stand-to-be-mounted by other females)
Videotape
Teasers (vasectomized [gomer] or penile-deflected bulls; steroid-treated steers or cows) fitted with marking devices (grease smeared on brisket; halter with a chin-ball marker)
Pressure-sensitive mount detectors placed on the rump of the cow
Increased physical activity monitored with pedometers
Ferning of cervical mucus
Decreased electrical resistance of cervical mucus measured by vaginal probe
Decreased vaginal pH
Increased uterine tone ascertained by rectal palpation
Estrus-related odors detected by trained dogs