Induction of ovulation using repeated doses of sulpiride, adopamine antagonist, in ewe lambs.

Abstract

This study aimed to test the hypothesis that sulpiride can increase the concentration of circulating gonadotropin that can promote puberty in pre-pubertal ewe lambs. Here, 12 1-3-year-old Merino rams and 60 7-9-month-old Merino sheep were included in the study. The sheep were randomly divided into sulpiride (n=30) and control (n=30) groups. The sulpiride group was subcutaneously injected with 0.6mg/kg sulpiride twice daily (morning and evening) for 9 days. During these 9 days, blood samples were taken from the sheep before drug administration and at 4 h after every drug administration. The number of ovulating animals in the sulpiride group was significantly higher than that in the control group (90% vs. 32%). No oestrous signs were observed in either group during ram release. Further, there were no differences in the levels of mean follicle-stimulating hormone in the two groups based on treatment (p=.2), time (p=.3) or treatment-by-time interaction (p=.3). After sulpiride administration, the luteinizing hormone (LH) levels of the sulpiride group rapidly increased and remained stable for a long time, whereas physiological LH fluctuations in the control group remained unchanged. Within-group changes in terms of LH concentrations were significant for both groups (p < .001), whereas LH pulse frequency was significantly different between the sulpiride group (p=.03). Therefore, it is concluded that sulpiride can be used as a non-steroidal alternative to stimulate pre-pubertal ewe lambs and sheep during anoestrus.