Abstract

LEHLOENYA, K.C.; GREYLING, J.P.C.; SCHWALBACH, L.M.J.  and  GROBLER, S.. Superovulatory response of Boer goat does pre-treated with a GnRH-agonist during the natural breeding season. S. Afr. j. anim. sci. [online]. 2006, vol.36, n.5, pp.63-66. ISSN 2221-4062.

A trial was conducted to evaluate the effect of pre-treatment with a GnRH agonist (GnRHa) on the superovulatory response in Boer goats during the natural breeding season. Twenty-one does were synchronised with CIDR's for 17 days and superovulated with a total dose of 200 mg FSH/doe, administered i.m. in seven dosages, at 12 h intervals, starting 48 h prior to CIDR removal (the first dose being 50 mg and all the others being 30 mg each). The treatment group (n = 11) additionally received a GnRHa (Lucrin^® 40 μg/day/doe) treatment for seven days, starting on day 7 of CIDR insertion, while the control group (n = 10) received only FSH. Laparoscopic inseminations with fresh diluted Boer goat semen were performed 36 h and 48 h following CIDR removal. Embryos were flushed six days following the second artificial insemination. The oestrous response (80 vs. 100%), onset (25.5 ± 7.4 h vs. 24.0 ± 7.4 h) and duration of the induced oestrous period (26.9 ± 4.0 vs. 19.6 ± 5.5 h) for the FSH and FSH/GnRHa treated groups, respectively, did not differ significantly. Similarly, no significant differences were recorded between groups in terms of the mean total number of structures, embryos and unfertilised ova flushed/doe. The pre-treatment with a GnRHa had no real advantage over the use of FSH alone, as it tended to reduce the number of transferable embryos (3.4 ± 2.7 vs. 9.3 ± 6.1, respectively) by increasing the total number of degenerated embryos (6.6 ± 4.2 vs. 1.7 ± 1.5, respectively) in Boer goats during the natural breeding season. Under these conditions treatment with GnRHa is not recommended.

Keywords : Does; oestrous synchronisation; MOET; embryo; Lucrin^®.

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