title: Testosterone of estradiol treatment of heifers or freemartins to detect estrus in confined dairy cattle.
abstract: Dairy heifers and freemartins were injected with either testosterone or estradiol and then used to detect estrus in mature dairy cows maintained indoors year-round on slatted-concrete floors. During a 15-mo period, 1,026 occurrences of estrus were confirmed from 339 cows. Observations by the herdsmen detected 92% of all occurrences of estrus compared to the heifers (39%) and freemartins (23%). There was great variation among animals in their ability to detect estrus. Conception rates were not affected by the method of detection of estrus.
authors.affiliation: Animal Research Centre Ottawa, Ontario, Canada K1A 0C6.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hackett