Document Detail


The effect of timing of administration of oestradiol benzoate on characteristics of oestrus, timing of ovulation and fertility in Bos indicus heifers synchronised with a progesterone releasing intravaginal insert.
MedLine Citation:
PMID:  12054285     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: To compare the timing of onset of oestrus and ovulation, characteristics of oestrus, and fertility in Bos indicus heifers synchronised with a progesterone releasing intravaginal insert (IVP4) and administration of oestradiol benzoate (ODB) either at the time of removal of the insert or 24 h later. Design: Cohort study. PROCEDURE: Bos indicus and Bos indicus cross heifers were treated on two farms (Farm A, n = 273; Farm B, n = 47) with an IVP4 for 8 days with 1.0 mg of ODB administered at the time of device insertion and 250 mg of cloprostenol at the time of device removal. Heifers in the ODB-0 group were administered 0.75 mg of ODB at the time of device removal while heifers in the ODB-24 group were administered the same dose of ODB 24 h after device removal. Heifers were inseminated once daily after detection of oestrus. Heifers not detected in oestrus by 72 h after removal of inserts were inseminated at that time. Oestrus was detected in heifers on Farm A using heatmount detectors while on Farm B oestrus in heifers was monitored using radiotelemetry of mounting pressure. Ovarian follicular development was monitored daily in 30 heifers on Farm B from the time of administration of inserts until ovulation to a maximum of 96 h after removal of inserts, and again 11 days after removal of inserts (Day 19). A blood sample was collected from all heifers on Farm B on Day 19 and analysed for plasma concentration of progesterone. Pregnancy was diagnosed 6 to 8 weeks after insemination. RESULTS: Administration of ODB at the time of removal of inserts shortened the time interval to oestrus and ovulation (P < 0.001), increased the number of mounts recorded during oestrus (P = 0.04) and reduced the odds of pregnancy (P = 0.03). The proportion of heifers ovulating on Farm B was 67% and was not affected by treatment group (P = 0.61). The mean diameter of the largest follicle measured in ovaries was greater at the time of removal of inserts (9.1 +/- 0.6 vs 10.7 +/- 0.4; P = 0.03) and at the expected time of the LH surge (8.1 +/- 0.4 vs 11.5 +/- 0.3 mm; P < 0.001) in heifers that ovulated compared to heifers that failed to ovulate, respectively. Emergence of a new follicular wave was not detected during the synchronisation treatment in heifers that failed to ovulate. Concentrations of progesterone in plasma on Day 19 were less in non-pregnant heifers (P = 0.05) compared to heifers subsequently diagnosed as pregnant to insemination and were affected by the diameter of the ovulatory follicle (P = 0.01). CONCLUSION: Administration of ODB at the time of removal of inserts can shorten the time interval to oestrus and ovulation and can reduce fertility when insemination is carried out once daily. Further work is needed to determine if prolonged suppression of follicular development, anovulatory oestrus and premature ovulation occuring in some heifers is associated with administration of ODB.
Authors:
J Cavalieri; C Coleman; H Rodrigues; K L Macmillan; L A Fitzpatrick
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Australian veterinary journal     Volume:  80     ISSN:  0005-0423     ISO Abbreviation:  Aust. Vet. J.     Publication Date:  2002 Apr 
Date Detail:
Created Date:  2002-06-10     Completed Date:  2002-08-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370616     Medline TA:  Aust Vet J     Country:  Australia    
Other Details:
Languages:  eng     Pagination:  217-23     Citation Subset:  IM    
Affiliation:
Department of Veterinary Science, University of Melbourne, Werribee, Victoria.
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MeSH Terms
Descriptor/Qualifier:
Administration, Intravaginal
Animals
Cattle / physiology*
Drug Administration Schedule
Estradiol / administration & dosage*,  analogs & derivatives*
Estrus / drug effects*
Estrus Synchronization / drug effects
Female
Injections, Intramuscular
Insemination, Artificial
Ovarian Follicle / drug effects,  physiology,  ultrasonography
Ovulation / drug effects*
Pregnancy
Progesterone / administration & dosage,  blood
Chemical
Reg. No./Substance:
50-28-2/Estradiol; 50-50-0/estradiol 3-benzoate; 57-83-0/Progesterone

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


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