Reversibility of the effects of GnRH-vaccination used to suppress reproductive function in mares

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dc.contributor.author Schulman, M.L. (Martin)
dc.contributor.author Botha, A.E.
dc.contributor.author Muenscher, Stefanie B.
dc.contributor.author Annandale, C.H. (Cornelius Henry)
dc.contributor.author Guthrie, Alan John
dc.contributor.author Bertschinger, H.J. (Hendrik Jan)
dc.date.accessioned 2013-04-17T07:33:32Z
dc.date.available 2014-01-31T00:20:03Z
dc.date.issued 2013-01
dc.description.abstract Reasons for performing study: Active immunisation against gonadotrophin-releasing hormone (GnRH) provides a reversible method for control of oestrous behaviour and fertility in mares. Previous reports failed to demonstrate the interval to resumption of cyclic ovarian activity after GnRH-vaccination. Hypothesis: Administration of the GnRH-vaccine ImprovacÒ1 in a large group of mares of various ages will result in effective, reliably reversible suppression of ovarian activity within a two-year period. Methods: The mares, subdivided into three age categories were vaccinated twice (with a 35 d interval) using ImprovacÒ1 and were monitored via blood samples until Day 720 after initial vaccination for serum progesterone concentration determination by radio-immune assay and anti-GnRH antibody titre by enzyme immuno-assay. Samples were collected until individuals resumed cyclic ovarian activity. Results: All mares showed suppression of cyclic ovarian activity (SPC <1 nmol/l) and 92.2% resumed cyclic activity at Day 720 with a mean interval = 417.8 d (SD = 23.19) and median = 344 d. A significant age effect (P=0.028) on the interval, but not on GnRH-AB titre response, was observed between the youngest (<4 years) and oldest (>11 years) categories. Conclusions: Immunising adult mares of all ages with ImprovacÒ1 resulted in a reversible suppression of cyclic ovarian activity in most mares. An age effect, with the youngest mares showing a longer interval to reversibility was observed. en
dc.description.librarian hb2013 en
dc.description.librarian ab2014
dc.description.sponsorship The Equine Research Centre of the University of Pretoria en
dc.description.uri http://www.evj.co.uk/journals/ en
dc.identifier.citation Schulman, ML, Botha, AE, Muenscher, SB, Annandale, CH, Guthrie, AJ & Bertschinger, HJ 2013, 'Reversibility of the effects of GnRH-vaccination used to suppress reproductive function in mares', Equine Veterinary Journal, vol. 45, no. 1, pp. 111-113. en
dc.identifier.issn 0425-1644 (print)
dc.identifier.issn 2042-3306 (online)
dc.identifier.other 10.1111/j.2042-3306.2012.00577.x
dc.identifier.other 7006535470
dc.identifier.other J-6375-2013
dc.identifier.other 0000-0001-7729-9918
dc.identifier.uri http://hdl.handle.net/2263/21295
dc.language.iso en en
dc.publisher Wiley-Blackwell en
dc.rights © 2012 EVJ Ltd. The definite version is available at http://www.evj.co.uk/journals/ en
dc.subject GnRH-vaccination en
dc.subject Horses en
dc.subject Mares en
dc.subject Anoestrus en
dc.subject Gonadotrophin-releasing hormone (GnRH) en
dc.subject Titres en
dc.subject Reversibility en
dc.subject.lcsh Vaccination of animals en
dc.subject.lcsh Mares -- Vaccination en
dc.subject.lcsh Luteinizing hormone releasing hormone en
dc.title Reversibility of the effects of GnRH-vaccination used to suppress reproductive function in mares en
dc.type Postprint Article en


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