AN INVESTIGATION ON THE SUSTAINED RELEASING DELIVERY OF GNRHA USING FREUND'S INCOMPLETE ADJUVANT (FIA) IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

In this study, Freund's incomplete adjuvant (FIA) was used for emulsifying and sustained releasing of gonadotropin releasing hormone agonist (GnRHa) in Rainbow trout (Oncorhynchus mykiss).The hormone [D-Ala6,des GlylO] m GnRHa was diluted in 0.25 ml physiological saline and mixed with equal volume of FIA (GnRHa-FIA). A group of Rainbow trout brood stock were injected with GnRHa-FIA and compared with those receiving the treatment in two steps or one acute GnRHa injection. All of the fish that received GnRHa in emulsified form or in two steps injection ovulated in 10 and 11 days after injection respectively. In contrast, only 75% of the control fish and 60% of the fish with an acute injection ovulated up to 36 days after injection. Results showed that GnRHa-FIA injection as two steps injection protocol was effective in advancing the onset of ovulation, synchronizing the ovulation of treated fish relative to controlor acute GnRHa injected groups (P<0.05). GnRHa-FIA neither affected egg quality (P<0.05) nor did it cause any mortality in the treated fish.