Praziquantel form, dietary application method and dietary inclusion level affect palatability and efficacy against monogenean parasites in yellowtail kingfish

Abstract

The bitterness of racemic praziquantel (PZQ) currently constrains its use as an infeed treatment against monogenean flukes in finfish aquaculture. In an effort to increase the palatability of diets containing racemic PZQ for yellowtail kingfish, the palatability and efficacy of 2 forms of racemic PZQ (powder or powder within microcapsules) against natural infestations of skin and gill flukes were compared using 2 different dietary application methods (incorporated within the pellet mash prior to extrusion or surface-coated after extrusion) at active dietary inclusion levels of 8, 16 and 25 g kg −1 in large (3.5−4 kg) yellowtail kingfish. There was no clear benefit of incorporating PZQ into diets prior to extrusion. PZQ microcapsules improved the palatability of PZQ-containing diets but did not completely mask the bitter flavour. At the lowest active dietary inclusion level of 8 g kg −1 , ingestion of the diet containing PZQ microcapsules was equal to the control and significantly better than that containing PZQ powder. At an inclusion level of 16 g kg −1, ingestion of the PZQ microcapsule diet was significantly better than that containing the same inclusion of PZQ powder but significantly lower than the control. Consumption of the diet containing 25 g kg −1 of PZQ microcapsules was poor. All fish consuming medicated feeds had a significant reduction in flukes relative to control fish; however, efficacy data and blood serum analysis suggested that diets containing PZQ microcapsules had lower bioavailability than those containing PZQ powder.

Praziquantel treatment for yellowtail kingfish (Seriola lalandi): dose and duration safety study

“…Few data are available, however, to indicate what the optimised dose is for oral delivery of praziquantel against flukes infecting yellowtail kingfish (YTK) (Seriola lalandi Valenciennes 1833), and contradictory information exists in the literature (e.g. compare Williams et al 2007;Partridge et al 2014). Data on the safety of these doses, furthermore, are not available.…”

A comparison of the palatability of racemic praziquantel and its two enantioseparated isomers in yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

“…Pellets were then top-coated with a 20% (w/v) gelatine solution at the rate of 50 mL kg À1 to adhere the PZQ to the surface (Partridge et al 2014). Prior to stocking, fish were anaesthetized [isoeugenol 20 mg L À1 (AQUI-S, Lower Hutt, New Zealand)] and weighed to the nearest 1 g on a digital balance.…”

“…Each treatment diet was prepared in a 500 g batch by thoroughly hand-mixing the required amount and type of PZQ powder. Pellets were then top-coated with a 20% (w/v) gelatine solution at the rate of 50 mL kg À1 to adhere the PZQ to the surface (Partridge et al 2014). Following the addition of gelatine, the Table 1 Treatments investigated in each trial.…”

“…The typical treatment for such parasites is the routine bathing of fish in hydrogen peroxide, a process which is labour intensive, logistically challenging and potentially dangerous to both the fish and operators if not properly executed. Praziquantel has been demonstrated to be effective against monogeneans infesting yellowtail kingfish Seriola lalandi (Valenciennes) (see Sharp et al 2004;Tubbs & Tingle 2006), as too has the constraint of its bitterness to in-feed application (Partridge et al 2014;Williams et al 2007). Praziquantel has been demonstrated to be effective against monogeneans infesting yellowtail kingfish Seriola lalandi (Valenciennes) (see Sharp et al 2004;Tubbs & Tingle 2006), as too has the constraint of its bitterness to in-feed application (Partridge et al 2014;Williams et al 2007).…”

“…Furthermore, this management practice is expensive, with estimates that it contributes up to 20% of the cost of production (Ernst, Whittington, Corneillie & Talbot 2005). Praziquantel has been demonstrated to be effective against monogeneans infesting yellowtail kingfish Seriola lalandi (Valenciennes) (see Sharp et al 2004;Tubbs & Tingle 2006), as too has the constraint of its bitterness to in-feed application (Partridge et al 2014;Williams et al 2007). The current study tested the hypothesis that enantioseparated R-(À) PZQ will be more palatable than Rac-PZQ, which will in turn be more palatable than S-(+)-PZQ to yellowtail kingfish.…”