Preparation of teaser bulls and steroid-implanted steers and their effectiveness in detecting estrus

T. J. McDonald, R. H. Foote, Maarten Drost, L. Lu, M. Patrascu, C. E. Hall

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Pen-O-Blocks were easily installed in 15 bulls. Libido appeared to be unaffected. However, with the exception of one bull, infections occurred, or the penis bypassed the block, or the pin broke, and in 14 tests the Pen-O-Blocks were removed within 5 weeks of installation. Recovery from infection following removal of the device was rapid and uneventful. Eight bulls had their penes deviated between 2 weeks and 4 months of age. Four of these also were castrated and implanted with androgens at 12 months of age. Semen quality and libido in the deviated bulls were normal. Bulls and steers were equipped with Chin Ball mating devices. Bulls generally were more effective than steers in detecting estrus. When placed in pens 24 hours per day with 20 heifers each, one bull detected 97% and another bull detected 100% of the potential estruses during a period of two months. An observer watching for .5 hours each morning and each late afternoon detected 74%. While steers were less effective, they were more docile than the bulls. Thus, with selection of active animals and adjustment of hormone therapy, implanted steers may be successful detectors of estrus with minimal danger to the owner. Reproductive development in the androgen-treated steers was delayed but maturation of the penis had occurred in steers slaughtered at 31 months of age. Body weight gains of steers tended to be accelerated during periods when they had implants.

Original languageEnglish (US)
Pages (from-to)51-60
Number of pages10
Issue number1
StatePublished - Jul 1976
Externally publishedYes

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine


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