Dietary β-glucan enhances the contents of complement component 3 and factor B in eggs of zebrafish

• Dietary β-glucan enhanced transfer of C3 and Bf from female zebrafish to eggs.
• Embryos from β-glucan-treated females were more resistant to pathogenic challenge.
• Transferred C3 and Bf were involved in antimicrobial defense of early embryos.
• β-glucan can be used safely to promote non-specific immunity of offspring.

β-glucan has been shown to increase non-specific immunity and resistance against infections or pathogenic bacteria in several fish species, but no information is available regarding its trans-generational effects to date. Here we clearly demonstrated that β-glucan enhanced the contents of immune-relevant molecules C3 and Bf in eggs of zebrafish, and the embryos derived from β-1,3 glucan-treated zebrafish were more resistant to bacterial challenge than control embryos. Moreover, the transferred C3 and Bf were directly associated with the antimicrobial defense of early embryos. In addition, feeding female zebrafish with β-glucan had little detrimental effects on the number of spawned eggs and their embryonic development. Collectively, these data show for the first time that β-glucan can be safely used to promote the non-specific immunity in offspring of fishes.