Document Detail

Estrus synchronization of beef cattle with a combination of melengestrol acetate and an injection of progesterone and 17beta-estradiol.
MedLine Citation:
PMID:  10229369     Owner:  NLM     Status:  MEDLINE    
Our hypothesis was that estrus synchronization in beef cattle using melengestrol acetate (MGA) and an injection of progesterone (P4) and 17beta-estradiol (E2) to regress dominant ovarian follicles would improve pregnancy rate (number conceived/number in group) to AI compared with feeding only MGA or injecting PGF2alpha. During 2 yr, peripubertal heifers (n = 52) and cows (n = 327) received either 1) MGA for 18 d (d 0 = 1st d of MGA) plus an injection of P4 and E2 in sesame oil (vehicle) on d 11 to regress persistent ovarian follicles (MGA+P4), 2) MGA for 18 d plus vehicle on d 11 (MGA), or 3) two injections of PGF2alpha 10 d apart (d 7 and 17, PG). Concentration of P4 was assessed in blood samples obtained on d 0, 7, and 17 to indicate estrual status (anestrual or estrual) during treatment to induce estrus synchrony. Observations for detection of estrus occurred every 6 h for 180 h following treatment cessation. Females showing estrus were inseminated 6 to 12 h after estrus detection. Conception to AI was determined by ultrasonography 35 to 40 d later. Conception rate was greater (P < .05) in females in the PG than in those in the MGA group but did not differ from conception rate of females in the MGA+P4 group. Among anestrual females, estrus synchrony rates were greatest (P < .10) among females treated with MGA+P4. Among females that were estrual before treatment cessation, estrus synchrony rates were greater (P < .10) among females treated with MGA+P4 or PG than among those given MGA. Pregnancy rates were greater (P < .05) among females that were anestrual before treatment cessation and treated with MGA or MGA+P4 than among those treated with PG. Estrus synchronization using MGA+P4 and E2 differentially improves estrus synchronization and pregnancy rates among anestrual and estrual beef cattle while maintaining conception rates similar to those of PGF2alpha-treated females.
K E Fike; M E Wehrman; B R Lindsey; E G Bergfeld; E J Melvin; J A Quintal; E L Zanella; F N Kojima; J E Kinder
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of animal science     Volume:  77     ISSN:  0021-8812     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-06-17     Completed Date:  1999-06-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  715-23     Citation Subset:  IM    
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
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MeSH Terms
Cattle / physiology*
Drug Combinations
Estradiol / blood,  pharmacology*
Estrus Synchronization / drug effects*
Insemination, Artificial / veterinary
Melengestrol Acetate / pharmacology*
Ovarian Follicle / drug effects
Pregnancy Rate
Progesterone / pharmacology*
Progesterone Congeners / pharmacology*
Reg. No./Substance:
0/Drug Combinations; 0/Progesterone Congeners; 2919-66-6/Melengestrol Acetate; 50-28-2/Estradiol; 57-83-0/Progesterone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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