| Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows. | |
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MedLine Citation:
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PMID: 11721849 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle was tested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectal ultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detected follicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P4; EB + P4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P4 and no CR (n = 9); EB + P4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P4 injections were given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P4 were compared to the EB + P4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P4 injection (10.6 +/- 1.2 d) than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size of ovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P4, and the subsequent luteal phase length was increased in animals that were administered EB + P4. |
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Authors:
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B E Salfen; F N Kojima; J F Bader; M F Smith; H A Garverick |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of animal science Volume: 79 ISSN: 0021-8812 ISO Abbreviation: J. Anim. Sci. Publication Date: 2001 Oct |
Date Detail:
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Created Date: 2001-11-27 Completed Date: 2002-04-09 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 8003002 Medline TA: J Anim Sci Country: United States |
Other Details:
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Languages: eng Pagination: 2688-97 Citation Subset: IM |
Affiliation:
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Department of Animal Sciences, University of Missouri-Columbia, 65211-5300, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Anestrus Animals Animals, Suckling Cattle / physiology* Drug Administration Schedule Estradiol / administration & dosage*, analogs & derivatives* Estrus Synchronization / drug effects* Female Ovarian Follicle / physiology*, ultrasonography Ovulation Induction / veterinary Postpartum Period Progesterone / administration & dosage* Time Factors Weaning |
| Chemical | |
Reg. No./Substance:
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50-28-2/Estradiol; 50-50-0/estradiol 3-benzoate; 57-83-0/Progesterone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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