Document Detail

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.
MedLine Citation:
PMID:  21094738     Owner:  NLM     Status:  MEDLINE    
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.
J C Green; C S Okamura; D J Mathew; E M Newsom; M C Lucy
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Journal of dairy science     Volume:  93     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-24     Completed Date:  2011-02-01     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5668-72     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Division of Animal Science, University of Missouri, Columbia 65211, USA.
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MeSH Terms
2',5'-Oligoadenylate Synthetase / metabolism
Cattle / metabolism,  physiology*
Estrus Synchronization / methods*
Insemination, Artificial / methods,  veterinary*
Pregnancy Tests / veterinary*
Progesterone / blood
Time Factors
Reg. No./Substance:
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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