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

D. J. Kesler, Dan 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 MGA per day for 14 days and then randomly assigned to receive FGF (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 PGF treatment were artificially inseminated at 72 h after PGF . Females in estrus within first 52 h and 78 h to 6 days after PGF were artificially inseminated based on estrus (am/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 PGF 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 PGF treatment and pregnancy rates for heifers and cows with 13, 15 and 17 day intervals from MGA to PGF 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 PGF treatment, 25 of the 65 (39%) females with only 72 h AI became pregnant. The combined G day synchronized pregnancy rate was 44% (38/86). In summary, acceptable pregnancy rates were obtained in beef heifers and cows synchronized with MGA and PGF and bred by a combined estrus detection (1, 2, 4, 5 and 6 days after PGF treatment) and timed insemination (72 h after PGF treatment) procedure.

Original languageEnglish (US)
Pages (from-to)73-81
Number of pages9
JournalJournal of Applied Animal Research
Volume11
Issue number1
StatePublished - Mar 1997
Externally publishedYes

Fingerprint

Melengestrol Acetate
Estrus Synchronization
melengestrol
estrus synchronization
Estrus
Prostaglandins F
prostaglandins
estrus
beef
Pregnancy Rate
pregnancy rate
beef cows
beef cattle
Therapeutics
heifers
Estrus Detection
cows
estrus detection
Insemination
Fibroblast Growth Factor 2

Keywords

  • Estrus synchronization
  • Melengestrol acetate
  • Prostaglandin (PGF )
  • Timed artificial insemination

ASJC Scopus subject areas

  • Animal Science and Zoology
  • veterinary(all)

Cite this

Synchronization of estrus in beef females with the melengestrol acetate/prostaglandin F procedure : Estrus and efficacy of 72-hour timed AI. / Kesler, D. J.; Faulkner, Dan B; Dyson, T. S.; Nash, T. G.

In: Journal of Applied Animal Research, Vol. 11, No. 1, 03.1997, p. 73-81.

Research output: Contribution to journalArticle

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abstract = "Thirty-eight beef heifers and 48 beef cows suckling calves were fed .5 mg of MGA per day for 14 days and then randomly assigned to receive FGF 2α (25 mg Lutalyse{\circledR}) 13, 15 and 17 days after the last day of MGA feeding. Females not in estrus for the first 52 h after PGF 2α treatment were artificially inseminated at 72 h after PGF 2α. Females in estrus within first 52 h and 78 h to 6 days after PGF 2α were artificially inseminated based on estrus (am/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 PGF 2α 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 PGF 2α treatment and pregnancy rates for heifers and cows with 13, 15 and 17 day intervals from MGA to PGF 2α 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 PGF 2α treatment, 25 of the 65 (39{\%}) females with only 72 h AI became pregnant. The combined G day synchronized pregnancy rate was 44{\%} (38/86). In summary, acceptable pregnancy rates were obtained in beef heifers and cows synchronized with MGA and PGF 2α and bred by a combined estrus detection (1, 2, 4, 5 and 6 days after PGF 2α treatment) and timed insemination (72 h after PGF 2α treatment) procedure.",
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