| Hot topic: Successful fixed-time insemination within 21 d after first insemination by combining chemical pregnancy diagnosis on d 18 with a rapid resynchronization program. | |
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MedLine Citation:
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PMID: 21094738 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Cattle that are not pregnant to first fixed-time artificial insemination (TAI) may be resynchronized for a second TAI if they are found nonpregnant at pregnancy diagnosis. The specific interval between first and second TAI ranges from 4 to 8 wk. The selected interval depends on the available method of pregnancy diagnosis and the efficiency of the resynchronization program. The objective of this experiment was to evaluate a pregnancy diagnosis and resynchronization system that achieved a 21-d interval between TAI. This 21-d interval approximates the natural return-to-service interval. It also enables resynchronization to be implemented within the same estrous cycle in which cattle are first inseminated. Holstein heifers were randomly assigned to a 21-d resynchronization program (21d_resynch; n = 40) or a control group in which estrus was observed for the purpose of re-insemination (control; n = 29). The 21d_resynch heifers were diagnosed for pregnancy on d 18 after a TAI (d 0) by using predetermined cut-off values for 2'-5' oligoadenylate synthetase 1 (Oas1) gene expression in leukocytes and plasma progesterone concentration. Heifers that were not pregnant to first TAI had greater expression of Oas1 at the time of PGF(2α) (d -3) than pregnant heifers, but this relationship was reversed on d 18 after TAI: the heifers that were pregnant to first TAI had almost 5-fold greater expression of Oas1 compared with nonpregnant heifers. Nonpregnant heifers in the 21d_resynch group were injected with a luteolytic dose of PGF(2α) on d 19 and were injected with GnRH on d 21 and submitted to TAI. The pregnancy per AI after first insemination was similar for 21d_resynch (50.0%; pregnancy diagnosis on d 18) and control (51.7%; pregnancy diagnosis on d 27). Likewise, no difference was detected in second insemination pregnancy per AI for 21d_resynch (36.8%; nonpregnant heifers TAI on d 21) and control (35.7%; nonpregnant heifers inseminated at return to estrus or after nonpregnant diagnosis on d 27). The interval between first and second insemination was shorter for 21d_resynch compared with control (21.0 ± 0 and 27.5 ± 2.1 d). The conclusion is that a TAI resynchronization can be programmed within 21 d of previous TAI when a d 18 pregnancy test and a rapid resynchronization are used. |
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Authors:
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J C Green; C S Okamura; D J Mathew; E M Newsom; M C Lucy |
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Publication Detail:
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Type: Journal Article; Randomized Controlled Trial |
Journal Detail:
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Title: Journal of dairy science Volume: 93 ISSN: 1525-3198 ISO Abbreviation: J. Dairy Sci. Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2010-11-24 Completed Date: 2011-02-01 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 2985126R Medline TA: J Dairy Sci Country: United States |
Other Details:
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Languages: eng Pagination: 5668-72 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved. |
Affiliation:
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Division of Animal Science, University of Missouri, Columbia 65211, USA. kevin_anderson@ncsu.edu |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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2',5'-Oligoadenylate Synthetase
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metabolism Animals Cattle / metabolism, physiology* Estrus Synchronization / methods* Female Insemination, Artificial / methods, veterinary* Pregnancy Pregnancy Tests / veterinary* Progesterone / blood Time Factors |
| Chemical | |
Reg. No./Substance:
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57-83-0/Progesterone; EC 2.7.7.-/2',5'-Oligoadenylate Synthetase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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