Document Detail

Effects of oxytocin on follicular development and duration of the estrous cycle in heifers.
MedLine Citation:
PMID:  10730982     Owner:  NLM     Status:  MEDLINE    
Holstein heifers were used to study effects of exogenous administration of oxytocin on luteal function and ovarian follicular development. Twelve heifers were monitored for 1 estrous cycle to confirm normal ovarian function. At the subsequent estrus, these animals were randomly assigned to 1 of 3 treatments: saline control, (Group 1, n=4), oxytocin (Group 2, n=4) and saline pregnant (Group 3, n=4). Group 2 received continuous infusion of oxytocin (1.9 mg/d) from Days 14 to 26 after estrus, while Groups 1 and 3 received saline infusion during the same period. Group 3 were artificially inseminated at estrus. Daily blood samples were collected for oxytocin and progesterone assay. Ovarian follicles and corpus luteum (CL) development were monitored daily by transrectal ultrasonography until Day 32 after estrus. Plasma progesterone (P4) concentrations prior to initiation of infusion were 7.6+/-1.3 ng/mL on Day 14. They then decreased to <1 ng/mL on Day 19 for Group 1 and on Day 28 for Group 2. The interestrous interval was longer (P <0.05) for heifers that received oxytocin infusion. During the infusion period P4 concentrations were not different (P >0.05) between Group 2 and 3 but declined gradually from Day 20 in Group 2 despite the presence of high plasma oxytocin concentrations. Control heifers had 2 waves of follicular growth, with the second dominant follicle ovulating. Three of the 4 oxytocin-infused animals had an additional wave, with the third dominant follicle ovulating. Oxytocin infusion had no effect on size of the ovulating follicle (P >0.05) and the number of Class 1 follicles (3 to 5 mm, P >0.1). Differences in the number of Class 2 follicles (6 to 9 mm) among treatments on Days 15 to 22 after estrus were not detected (P >0.1) except on Days 23 to 26, when Group 2 had fewer follicles than Group 3 (P <0.05). The results show that continuous infusion of oxytocin during normal luteolysis delays luteal regression without inhibiting follicular development.
S K Tallam; J S Walton; W H Johnson
Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Theriogenology     Volume:  53     ISSN:  0093-691X     ISO Abbreviation:  Theriogenology     Publication Date:  2000 Mar 
Date Detail:
Created Date:  2000-05-04     Completed Date:  2000-05-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  951-62     Citation Subset:  IM    
Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Cattle / physiology*
Estrus / drug effects*
Ovarian Follicle / drug effects*,  physiology*
Ovary / physiology
Oxytocin / blood,  pharmacology*
Progesterone / blood
Reg. No./Substance:
50-56-6/Oxytocin; 57-83-0/Progesterone

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

Previous Document:  Termination of mid-gestation pregnancy in bitches with aglepristone, a progesterone receptor antagon...
Next Document:  Effects of oxytocin on cloprostenol-induced luteolysis, follicular growth, ovulation and corpus lute...