Document Detail

A new presynchronization system (Double-Ovsynch) increases fertility at first postpartum timed AI in lactating dairy cows.
MedLine Citation:
PMID:  18468675     Owner:  NLM     Status:  MEDLINE    
This study evaluated a novel presynchronization method, using Ovsynch prior to the Ovsynch-timed AI protocol (Double-Ovsynch) compared to Presynch-Ovsynch. Lactating Holstein (n=337) cows, were assigned to two treatment groups: (1) Presynch (n=180), two injections of PGF 14 d apart, followed by the Ovsynch-timed AI protocol 12 d later; (2) Double-Ovsynch (n=157), received GnRH, PGF 7 d later, and GnRH 3 d later, followed by the Ovsynch-timed AI protocol 7 d later. All cows received the same Ovsynch-timed AI protocol: GnRH (G1) at 68+/-3 DIM (mean+/-SEM), PGF 7 d later, GnRH (G2) 56h after PGF, and AI 16 to 20h later. Pregnancy was diagnosed 39-45 d after timed AI. Double-Ovsynch increased the pregnancies per AI (P/AI) compared to Presynch-Ovsynch (49.7% vs 41.7%, P=0.03). Surprisingly, Double-Ovsynch increased P/AI only in primiparous (65.2% vs 45.2%; P=0.02) and not multiparous (37.5% vs 39.3%) cows. In a subset of 87 cows, ovarian ultrasonography and progesterone (P4) measurements were performed at G1 and 7 d later. Double-Ovsynch decreased the percentage of cows with low P4 (<1ng/mL) at G1 (9.4% vs 33.3%) and increased the percentage of cows with high P4 (> or =3ng/mL) at PGF (78.1% vs 52.3%). Thus, presynchronization of cows with Double-Ovsynch increased fertility in primiparous cows compared to a standard Presynch protocol, perhaps due to induction of ovulation in non-cycling cows and improved synchronization of cycling cows. Future studies are needed, with a larger number of cows, to further test the hypothesis of higher fertility with Double-Ovsynch, and to elucidate the physiological mechanisms that underlie apparent changes in fertility with this protocol.
A H Souza; H Ayres; R M Ferreira; M C Wiltbank
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Publication Detail:
Type:  Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-05-12
Journal Detail:
Title:  Theriogenology     Volume:  70     ISSN:  0093-691X     ISO Abbreviation:  Theriogenology     Publication Date:  2008 Jul 
Date Detail:
Created Date:  2008-06-16     Completed Date:  2008-11-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  208-15     Citation Subset:  IM    
Department of Animal Reproduction, University of São Paulo, São Paulo 05508, Brazil.
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MeSH Terms
Cattle / physiology*
Dinoprost / administration & dosage,  pharmacology*
Estrus Synchronization / methods*
Fertility Agents, Female / administration & dosage,  pharmacology
Gonadotropin-Releasing Hormone / administration & dosage,  pharmacology*
Insemination, Artificial / veterinary*
Lactation / physiology*
Ovary / drug effects,  physiology
Postpartum Period
Pregnancy Rate
Reg. No./Substance:
0/Fertility Agents, Female; 33515-09-2/Gonadotropin-Releasing Hormone; 551-11-1/Dinoprost

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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