Dietary bovine lactoferrin enhances defense factors on body surface and anti-parasitic effects against Neobenedenia girellae infection, and mitigates low-salinity stress in amberjack (Seriola dumerili) juveniles

Abstract

This study investigated the effects of bovine lactoferrin (bLf) on the body surface defense factors, stress response to fresh water exposure, and anti-parasitic effects against Neobenedenia girellae in amberjack (Seriola dumerili) juveniles. In the first trial, amberjack juveniles were fed test diets supplemented with four different levels of bLf (0, 500, 1000, and 2000 mg kg−1) for 4 weeks to determine the appropriate bLf supplement level and feeding duration, and stress responses to short-term fresh water exposure followed by recovery at ambient salinity were also measured. This showed that a diet supplemented with ≥1000 mg bLf kg−1 for 2 weeks improved skin mucus production, non-specific defense factors, and mitigated stress. In the second trial, amberjack juveniles were fed diets supplemented with 0 and 1000 mg bLf kg−1 for 2 weeks and challenged by N. girellae oncomiracidia. It was found that fish that had been fed a diet supplemented with 1000 mg bLf kg−1 had significantly fewer parasites than fish that had been fed the unsupplemented control diet. Together, these results suggest that dietary bLf enhances defense ability the body surface, mitigates low-salinity stress, and enhances anti-parasitic effects against N. girellae oncomiracidia in amberjack juveniles.