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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
3
|
| pubmed:dateCreated |
1997-5-27
|
| pubmed:abstractText |
Experiments were conducted to test the hypothesis that estrogen treatment will regress a persistent dominant follicle developed during melengestrol acetate (MGA) treatment in the absence of a functional corpus luteum (CL) with normal fertility following development and ovulation of a newly recruited follicle. In Exp. 1, nonlactating beef cows (n = 31) were administered .5 mg.cow-1.d-1 of MGA (d 0) for 14 d with 25 mg of prostaglandin F2 alpha (PGF2 alpha) administered on d 6 and 8 to regress the CL. On d 11 of treatment, approximately half the MGA-treated cows received 5 mg of estradiol valerate (EV) i.m. (MGAEV, n = 14) and the remainder were maintained on MGA (n = 17). Ovaries were checked with ultrasound on d 8, 10, 12, and 14 of MGA treatment and every day until ovulation. A persistent dominant follicle developed in 90% of the MGA-treated cows by d 10 of treatment. Most of the MGA-treated cows ovulated the persistent dominant follicle (n = 13/17), whereas EV treatment regressed the persistent dominant follicle (n = 10/14) with the recruitment of a new follicle that ovulated (n = 8/10). Diameter of the ovulatory follicle was larger (P < .05) for the MGA (19.8 +/- .6 mm) than for the control (15.1 +/- .8 mm) and MGAEV (14.8 +/- .7 mm) cows. In Exp. 2, nonlactating, multiparous beef cows (n = 97) and yearling heifers (n = 38) were equally allotted to either a control, MGA alone, or MGA + estradiol-17 beta (MGAE) group with the same dose of MGA as administered in Exp. 1. The 1st d of MGA feeding was the 1st d of treatment. On d 10 of treatment half the MGA-treated animals were injected i.m. with 5 mg of estradiol-17 beta. In controls, behavioral estrus was detected and animals were artificially inseminated (AI) for 5 d (d 10 to 14 of experiment). All controls not exhibiting estrus by d 15 of experiment were injected with 25 mg of PGF2 alpha. The remaining controls and all MGA cows were observed for behavioral estrus and AI commenced for 7 d following withdrawal of MGA (d 15 to 21 of experiment). More (P < .05) controls (90.3%) than MGA (84.8%) or MGAE (63.6%) cows showed estrus within 7 d after MGA withdrawal. The percentage of animals conceiving to the synchronized estrus did not differ (P > .05) among treatments. The data support our hypothesis that a persistent dominant follicle developed and can be regressed with exogenous estrogen treatment followed by the recruitment and ovulation of a new follicle after MGA withdrawal and fertility of that estrus does not seem to be significantly compromised.
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| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Dinoprost,
http://linkedlifedata.com/resource/pubmed/chemical/Estradiol,
http://linkedlifedata.com/resource/pubmed/chemical/Estrogens,
http://linkedlifedata.com/resource/pubmed/chemical/Melengestrol Acetate,
http://linkedlifedata.com/resource/pubmed/chemical/Progesterone,
http://linkedlifedata.com/resource/pubmed/chemical/Progesterone Congeners
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Mar
|
| pubmed:issn |
0021-8812
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| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
75
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| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
745-54
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| pubmed:dateRevised |
2003-11-14
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| pubmed:meshHeading |
pubmed-meshheading:9078492-Animals,
pubmed-meshheading:9078492-Cattle,
pubmed-meshheading:9078492-Dinoprost,
pubmed-meshheading:9078492-Drug Synergism,
pubmed-meshheading:9078492-Estradiol,
pubmed-meshheading:9078492-Estrogens,
pubmed-meshheading:9078492-Estrus,
pubmed-meshheading:9078492-Estrus Synchronization,
pubmed-meshheading:9078492-Female,
pubmed-meshheading:9078492-Luteolysis,
pubmed-meshheading:9078492-Melengestrol Acetate,
pubmed-meshheading:9078492-Ovarian Follicle,
pubmed-meshheading:9078492-Ovary,
pubmed-meshheading:9078492-Ovulation,
pubmed-meshheading:9078492-Pregnancy,
pubmed-meshheading:9078492-Pregnancy Rate,
pubmed-meshheading:9078492-Progesterone,
pubmed-meshheading:9078492-Progesterone Congeners,
pubmed-meshheading:9078492-Random Allocation,
pubmed-meshheading:9078492-Time Factors
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| pubmed:year |
1997
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| pubmed:articleTitle |
Persistence of the dominant follicle during melengestrol acetate administration and its regression by exogenous estrogen treatment in beef cattle.
|
| pubmed:affiliation |
Department of Animal Science, Oklahoma State University, Stillwater 74078-0425, USA.
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| pubmed:publicationType |
Journal Article
|