Document Detail

Resynchronization strategies to improve fertility in lactating dairy cows utilizing a presynchronization injection of GnRH or supplemental progesterone: I. Pregnancy rates and ovarian responses.
MedLine Citation:
PMID:  20723683     Owner:  NLM     Status:  MEDLINE    
Objectives were to evaluate 3 resynchronization protocols for lactating dairy cows. At 32+/-3 d after pre-enrollment artificial insemination (AI; study d -7), 1 wk before pregnancy diagnosis, cows from 2 farms were enrolled and randomly assigned to 1 of 3 resynchronization protocols after balancing for parity, days in milk, and number of previous AI. All cows were examined for pregnancy at 39+/-3 d after pre-enrollment AI (study d 0). Cows enrolled as controls (n=386) diagnosed not pregnant were submitted to a resynchronization protocol (d 0-GnRH, d 7-PGF2alpha, and d 10-GnRH and AI) on the same day. Cows enrolled in the GGPG (GnRH-GnRH-PGF2alpha-GnRH) treatment (n=357) received a GnRH injection at enrollment (d -7) and if diagnosed not pregnant were submitted to the resynchronization protocol for control cows on d 0. Cows enrolled in CIDR treatment (n=316) diagnosed not pregnant received the resynchronization protocol described for control cows with addition of a controlled internal drug release (CIDR) insert containing progesterone (P4) from d 0 to 7. In a subgroup of cows, ovaries were scanned and blood was sampled for P4 concentration on d 0 and 7. After resynchronized AI, cows were diagnosed for pregnancy at 39+/-3 and 67+/-3 d (California herds) or 120+/-3 d (Arizona herds). Cows in the GGPG treatment had more corpora lutea than CIDR and control cows on d 0 (1.30+/-0.11, 1.05+/-0.11, and 1.05+/-0.11, respectively) and d 7 (1.41+/-0.14, 0.97+/-0.13, and 1.03+/-0.14, respectively). A greater percentage of GGPG cows ovulated to GnRH given on d 0 compared with CIDR and control cows (48.4, 29.6, and 36.6%, respectively), but CIDR and control did not differ. At 39+/-3 d after resynchronized AI, pregnancy per AI (P/AI) was increased in GGPG (33.6%) and CIDR (31.3%) cows compared with control (24.6%) cows. At 67 or 120+/-3 d after resynchronized AI, P/AI of GGPG and CIDR cows was increased compared with control cows (31.2, 29.5, and 22.1%, respectively). Presynchronizing the estrous cycle of lactating dairy cows with a GnRH 7 d before the start of the resynchronization protocol or use of a CIDR insert within the resynchronization protocol resulted in greater P/AI after resynchronized AI compared with control cows.
S T Dewey; L G D Mendonça; G Lopes; F A Rivera; F Guagnini; R C Chebel; T R Bilby
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  93     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-08-20     Completed Date:  2010-11-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4086-95     Citation Subset:  IM    
Copyright Information:
Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
University of Arizona, Department of Animal Sciences, Tucson 85721, USA.
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MeSH Terms
Abortion, Veterinary / physiopathology
Estrus Synchronization / methods*,  physiology
Gonadotropin-Releasing Hormone / blood,  pharmacology*
Insemination, Artificial / methods,  veterinary
Lactation / physiology
Milk / secretion
Ovary / drug effects*,  ultrasonography
Pregnancy Rate
Progesterone / blood,  pharmacology*
Reg. No./Substance:
33515-09-2/Gonadotropin-Releasing Hormone; 57-83-0/Progesterone

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

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