Synchronization of estrus in beef females with the melengestrol acetate/prostaglandin f2a procedure: Estrus and efficacy of 72-hour timed ai

D. J. Kesler, D. B. Faulkner, T. S. Dyson, T. G. Nash

Research output: Contribution to journalArticle

Abstract

Thirty-eight beef heifers and 48 beef cows suckling calves were fed .5 mg of MG A per day for 14 days and then randomly assigned to receive FGF., U (25 mg Lutalyse®) 13, 15 and 17 days after the last day of MGA feeding. Females not in estrus for the first 52 h after PGF2u treatment were artificially inseminated at 72 h after PGF2u. Females in estrus within first 52 h and 78 h to 6 days after PGF2a were artificially inseminated based on estrus (am I pm rule). Pregnancy was determined per rectum 44 to 47 days after the 72 h AI. Only two of the 86 females (2%) were in estrus during the 14 day MGA feeding period. During the interval from the last day of MGA feeding to PGF2a treatment 16 of the heifers (42%) and 6 of the cows (13%) were in estrus after an average of 5.4 + .4 days after the last day of MGA feeding. Estrus response after PGF2u treatment and pregnancy rates for heifers and cows with 13, 15 and 17 day intervals from MGA to PGF2a treatment were similar(P>0.10) and summarized together. Only 5 of the 86 females (6%) were in estrus 1 or 2 days before the 72 h AI while 16 of the 86 females (19%) were in estrus 1 to 3 days after the 72 h AI. Two of the 5 females (40%) in estrus before the 72 h AI became pregnant while 11 of the 16 females (69%) in estrus after the 72 h AI became pregnant. Of the other 65 females, although only 2 were detected in estrus 52 to 78 h after PGF2u treatment, 25 of the 65 (39%) females with only 72 h AI became pregnant. The combined 6 day synchronized pregnancy rate was 44% (38/86). In summary, acceptable pregnancy rates were obtained in beef heifers and cows synchronized with MGA and PGF2aL and bred by a combined estrus detection (1, 2, 4, 5 and 6 days after PGF2a treatment) and timed insemination (72 h after PGF2u treatment) procedure.

Original languageEnglish (US)
Pages (from-to)73-81
Number of pages9
JournalJournal of Applied Animal Research
Volume11
Issue number1
DOIs
StatePublished - Jan 1 1997

Keywords

  • Estrus synchronization
  • Melengestrol acetate
  • Prostaglandin (PGF2a)
  • References
  • Timed artificial insemination

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)

Fingerprint Dive into the research topics of 'Synchronization of estrus in beef females with the melengestrol acetate/prostaglandin f2a procedure: Estrus and efficacy of 72-hour timed ai'. Together they form a unique fingerprint.

  • Cite this