Document Detail


Characteristics of estrus before and after first insemination and fertility of heifers after synchronized estrus using GnRH, PGF2alpha, and progesterone.
MedLine Citation:
PMID:  12462245     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Our objectives were to determine fertility of heifers after synchronization of estrus using PGF2alpha, preceded by progesterone (P4), GnRH, or both, and to examine the variability of estrual characteristics in heifers before first and second AI. Dairy (n = 247) and beef (n = 193) heifers were assigned randomly to each of three treatments: 1) 50 microg of GnRH (injected i.m.) administered on d -7 followed by 25 mg of PGF2alpha (i.m.) on d -1 (GnRH + PGF; modified Select Synch protocol); 2) placement of an intravaginal progesterone (P4)-releasing insert on d -7, PGF2alpha on d -1, and insert removal on d 0 (P4+PGF); and 3) 50 microg of GnRH plus a P4 insert on d -7, followed by 25 mg of PGF2alpha on d -1, and insert removal on d 0 (P4+GnRH+PGF). Characteristics of estrus were examined before first AI and before the next eligible AI (18 to 26 d later), including duration of estrus, number of standing events, and total and individual duration of standing events. In addition, all heifers were checked visually at least twice daily for estrus. Blood samples were collected on d -7, -1, and 0 for determination of P4, and pregnancy status was diagnosed by ultrasonography 27 to 34 d after AI. Rates of detected estrus were less (P < 0.05) in dairy than in beef heifers, and greater (P < 0.05) in heifers treated with P4. Pattern of conception and pregnancy rates among treatments differed between beef and dairy heifers (treatment x group interaction; P < 0.05). In dairy heifers, conception and pregnancy rates were greatest with P4+PGF, followed by P4+GnRH+PGF and GnRH+PGF, respectively. The opposite was observed among treatments in beef heifers. Administration of P4 without the preceding injection of GnRH produced the lowest pregnancy rates in beefheifers. Ofthe quantified sexual behavioral characteristics during the synchronized estrus, the number of standing events and total duration of standing events were greater (P < 0.01) than those observed during the next eligible estrus before second AI, whereas duration of estrus was unaffected.
Authors:
A M Richardson; B A Hensley; T J Marple; S K Johnson; J S Stevenson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of animal science     Volume:  80     ISSN:  0021-8812     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2002 Nov 
Date Detail:
Created Date:  2002-12-03     Completed Date:  2003-03-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2792-800     Citation Subset:  IM    
Affiliation:
Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cattle / physiology*
Dinoprost / pharmacology*
Estrus / drug effects*
Estrus Detection
Estrus Synchronization
Female
Fertility / drug effects*
Gonadotropin-Releasing Hormone / pharmacology*
Insemination, Artificial / veterinary
Pregnancy
Pregnancy Rate
Progesterone / blood,  pharmacology*
Random Allocation
Reproduction / drug effects
Chemical
Reg. No./Substance:
33515-09-2/Gonadotropin-Releasing Hormone; 551-11-1/Dinoprost; 57-83-0/Progesterone

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


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