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

Show simple item record Schulman, M.L. (Martin) Botha, A.E. Muenscher, Stefanie B. Annandale, C.H. (Cornelius Henry) Guthrie, Alan John Bertschinger, H.J. (Hendrik Jan) 2013-04-17T07:33:32Z 2014-01-31T00:20:03Z 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 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.language.iso en en
dc.publisher Wiley-Blackwell en
dc.rights © 2012 EVJ Ltd. The definite version is available at 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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