Dietary ascorbyl phosphate results in high ascorbic acid content in eggs of rainbow trout

Abstract

Female and male rainbow trout during their second reproductive cycle were individually tagged and fed ascorbic acid-free (-AA), ascorbic acid (AA) or ascorbyl mono-phosphate (AP) supplemented diets (equivalent of 300 mg AA/kg). The body weight of AP females increased by 42.1 ± 24.1% between the first and second spawning. AA and -AA groups suffered severe mortality. Total ascorbic acid concentration in eggs of AP females ( n = 5) averaged 249 ± 36 μg g −1 and did not correlate with the survival of embryos (46.4 ± 22.2% hatching rate). Embryos utilized 26.3% of their ascorbic acid reserves during embryonic development, and no significant change in the total ascorbic acid pool from hatching to beginning of the exogenous feeding was evident. We conclude that the ascorbic acid requirement for broodstock rainbow trout might be higher than for the growth of immature fish. AP is an excellent source of stable ascorbic acid and is efficiently transferred to eggs and offspring.