| Introduction of bulls at different days postpartum on resumption of ovarian cycling activity in primiparous beef cows. | |
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MedLine Citation:
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PMID: 16100065 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The objective of this study was to evaluate postpartum resumption of ovulatory cycles among primiparous, suckled beef cows that were exposed continuously to mature bulls beginning at various intervals after calving. We sought to determine whether cumulative distributions of proportions of cows resuming ovarian cycles and interval from the start of bull exposure to resumption of ovarian cycling activity differed among cows exposed continuously (BE) or not exposed (NE) to bulls beginning on d 15, 35, or 55 after calving. Angus x Hereford cows (n = 56) were assigned randomly to one of six treatments in a 2 (exposure type) x 3 (day exposed postpartum) factorial arrangement. Blood samples were collected from each cow starting on d -1, and every third day until the end of experiment. An increase in baseline progesterone concentrations that exceeded 1.0 ng/mL in three consecutive samples was used as evidence of resumption of ovarian cycling activity. More (P < 0.05) BE cows resumed cycling activity by the end of the experiment than NE cows. Proportions of cows resuming cycling activity did not differ (P = 0.30) among cows exposed to bulls on d 15, 35, or 55 postpartum. Proportions of BE cows that were exposed to bulls on d 15, 35, or 55 were greater for each 10-d interval (P < 0.05) than those for NE cows during the first 40 d after exposure. More (P < 0.05) BE cows exposed to bulls on d 55 resumed cycling activity by 30 d after exposure than BE cows exposed to bulls on either d 15 or 35. Interval from calving to resumption of cycling activity was decreased (P < 0.05) by the presence of bulls. Day of exposure did not affect (P = 0.21) interval from calving to resumption of cycling activity; however, interval from day of bull exposure to resumption of cycling activity decreased (P < 0.05) linearly as day of exposure to bulls after calving increased. We conclude that exposing primiparous beef cows to bulls decreased the postpartum anovulatory interval and increased the proportion of cows that exhibit resumption of ovarian cycling activity, independent of day of bull exposure. Furthermore, cows exposed to bulls at progressively later intervals postpartum seemed to respond more rapidly to the biostimulatory effect of bulls than when they were exposed earlier in the postpartum anestrous period. |
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Authors:
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J G Berardinelli; P S Joshi |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Journal of animal science Volume: 83 ISSN: 1525-3163 ISO Abbreviation: J. Anim. Sci. Publication Date: 2005 Sep |
Date Detail:
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Created Date: 2005-08-15 Completed Date: 2008-01-02 Revised Date: - |
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: 2106-10 Citation Subset: IM |
Affiliation:
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Department of Animal and Range Sciences, Montana State University, Bozeman, 59717, USA. jgb@montana.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cattle / physiology* Female Least-Squares Analysis Male Menstrual Cycle / physiology* Parity Postpartum Period / physiology* Pregnancy Progesterone / blood Random Allocation Sexual Behavior, Animal* Time Factors |
| Chemical | |
Reg. No./Substance:
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57-83-0/Progesterone |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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