Document Detail

Ultrasound and endocrine evaluation of the ovarian response to a single dose of 500 IU of eCG following a 12-day treatment with progestogen-releasing intravaginal sponges in the breeding and nonbreeding seasons in ewes.
MedLine Citation:
PMID:  14662131     Owner:  NLM     Status:  MEDLINE    
A standard dose of 500 IU of eCG is commonly given to progestogen pre-treated anestrous ewes for induction of estrus. Twelve seasonally anestrous and 12 cyclic Western White Face ewes were treated for 12 days with intravaginal sponges impregnated with medroxyprogesterone acetate (MAP). In trials in both the breeding and nonbreeding seasons, six randomly selected ewes were given 500 IU of eCG at sponge removal to determine the effects of low dose of eCG on ovarian antral follicular dynamics and ovulation. Ultrasound scanning and blood sampling were done daily. Treatment with eCG did not have marked effects on antral follicular growth. All ewes ovulated, except for five of six control anestrous ewes. Luteal structures and progesterone secretion were confirmed in all but the control anestrous ewes. In the breeding season, peak progesterone concentrations were greater (P<0.05) in eCG-treated compared to control ewes. Daily serum estradiol concentrations were greater in the periovulatory period in eCG-treated compared to control ewes (treatment-by-day interaction; P<0.05), particularly in anestrus. Progestogen-treated ewes ovulated follicles from several follicular waves, in contrast to ovulations of follicles from the final wave of the cycle in untreated, cyclic ewes. Anestrous ewes exhibited more frequent follicular waves and FSH peaks compared to cyclic ewes after a progestogen/eCG treatment. In conclusion, 500 IU of eCG given after 12 days of progestogen treatment had limited effects on the dynamics of ovarian follicular waves. However, eCG treatment increased serum concentrations of estradiol during the periovulatory period, particularly in anestrous ewes; this probably resulted in the synchronous estrus and ovulation in anestrous ewes.
D M W Barrett; P M Bartlewski; M Batista-Arteaga; A Symington; N C Rawlings
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Theriogenology     Volume:  61     ISSN:  0093-691X     ISO Abbreviation:  Theriogenology     Publication Date:  2004 Jan 
Date Detail:
Created Date:  2003-12-09     Completed Date:  2004-03-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  311-27     Citation Subset:  IM    
Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4.
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MeSH Terms
Anestrus / drug effects
Corpus Luteum / physiology
Estradiol / blood
Estrus Synchronization
Follicle Stimulating Hormone / blood
Gonadotropins, Equine / administration & dosage*
Ovarian Follicle / drug effects,  physiology
Ovary / drug effects*,  physiology,  ultrasonography*
Progesterone / blood
Progestins / administration & dosage*
Reg. No./Substance:
0/Gonadotropins, Equine; 0/Progestins; 50-28-2/Estradiol; 57-83-0/Progesterone; 9002-68-0/Follicle Stimulating Hormone

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