INCREASES IN OVULATION RATE AND GONADOTROPIN CONCENTRATION IN GOATS AND MERINO SHEEP AFTER TREATMENT WITH BOVINE FOLLICULAR-FLUID

In this study we treated mixed-breed goat does and Merino ewes with bo vine follicular fluid (bFF), a rich source of the ovarian hormone inhi bin, to test the hypothesis that treatment will increase ovulation rat e. Twenty-two goat does of mixed breeding (non-dairy) and 24 Merino ew es were each divided into two equal groups and injected subcutaneously every 8 h with 2 ml of either saline or charcoal-extracted bFF for th e final 4 days of the luteal phase. Luteolysis was induced 8 h after t he last injection with a synthetic protaglandin. The concentrations of follicle-stimulating hormone (FSH) and luteinising hormone (LH) in bl ood plasma were monitored daily during treatment and then every 8 h fo r 3 days after luteolysis. Ovulation rate was determined by laparoscop y on Day 11 of the subsequent cycle. During treatment with bFF the pla sma concentration of FSH in both the ewes and the does was significant ly (P<0.01) reduced; however, the plasma concentration of LH in the do es was not reduced by bFF treatment. When the treatment with bFF was s topped, FSH concentrations increased three-fold over normal control le vels. The LH concentrations of both the control and the bFF-treated do es increased (P<0.01) after withdrawal of treatment, but the maximum v alue of the bFF-treated does was two-fold higher than that of the cont rol does. Ovulation rate significantly increased by 40% from 1.17 to 1 .64 in the ewes (P<0.05), and by 29% from 1.55 to 2.00 in the does (P< 0.05). The results from this study extend on other reports on the effe ct of high doses of follicular fluid in highly fecund breeds of sheep by showing that ovulation rate can be increased with low doses in goat s and low fecundity Merino sheep.