Effect of gonadotropin-releasing hormone on fertility in repeat-breeder California dairy cows

Robert Bondurant, I. Revah, C. Franti, R. J. Harman, D. Hird, D. Klingborg, M. McCloskey, L. Weaver, B. Wilgenberg

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


To assess the potential benefit to fertility from gonadotropin-releasing hormone (GnRH) administration to third service cows managed in typical California dairy systems, 963 cows were enlisted from 14 dairies served by 6 veterinary practices. The cows were randomly assigned to receive either GnRH (100 μg) or placebo at the time of the third artificial insemination. Fertility data were entered onto a proprietary microcomputer program common to all six practices, and collated independently by a third party. For the duration of the trial (1 yr), GnRH and placebo-treated cows had 43.2 and 39.3% conception rates, respectively (P=0.35). When treatments administered in summer months (July, August, September) were excluded, conception rates were 48.1 and 41.0%, respectively (P<0.1). The conception rates of cows treated with GnRH in August tended to be lower than those of placebo-treated cows (95% logarithmic confidence intervals of odds ratio = -1.139, 0.377). Between-herd variation in benefit from GnRH was evident, with two dairies showing no benefit, one dairy showing a negative effect, and four showing a range of effects from lightly beneficial to significantly beneficial. First-lactation cows did not benefit at any time from GnRH treatment. The data suggest that GnRH administered to third-service dairy cows under California conditions may result in increased conception rates in non-summer months, but that other unidentified variables may have important influence on the outcome of such treatment.

Original languageEnglish (US)
Pages (from-to)365-374
Number of pages10
Issue number2
StatePublished - Jan 1 1991
Externally publishedYes


  • conception rate
  • GnRH
  • infertility
  • repeat-breeder

ASJC Scopus subject areas

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


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