Evaluation of Natural-Source Vitamin E, RRR-α-Tocopheryl Acetate, as a Micronutrient in Sunshine Bass Feed

Abstract

A variety of vitamin E isomers can be used in the manufacture of animal feeds, though the efficacy of these sources varies. Our purpose was to evaluate natural-source vitamin E, RRR-α-tocopheryl acetate (NSVE), as an alternative to synthetic vitamin E, all-rac-α-tocopheryl acetate (SYNE), in the diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Our specific objectives were to evaluate graded levels of NSVE in terms of meeting the vitamin E requirement of sunshine bass and to address the physiological and economic suitability of NSVE by direct comparison with SYNE. Five isocaloric, isonitrogenous, semipurified diets were prepared and supplemented with NSVE at 0, 10, 20, or 30 mg/kg or SYNE at 30 mg/kg. Each dietary treatment was fed to fish in four replicate tanks, each housing 10 juvenile sunshine bass (mean weight = 25.1 g) in a recirculating system. One-way multiple analysis of variance (MANOVA) indicated that significant differences among treatment groups (Wilks' λ = 0.006) were most greatly attributable to differential survival, growth, food conversion ratio, and liver aldehyde concentration. Fish fed diets containing NSVE at less than 22 mg /kg (as-fed concentration, or 20 mg/kg supplemental dietary treatment) exhibited significantly lower survival (≤65% versus ≥92%) and weight gain (≤359% versus ≥591%), impaired food conversion ratio (2.9 versus ≤1.9), and evidence of heightened liver tissue oxidation (aldehyde, 0.62 nmol/g of tissue versus ≤0.22 nmol/g). Fish fed diets containing an NSVE as-fed concentration of 22 mg/kg or more exhibited performance equivalent to those fed the SYNE control within all parameters. Accordingly, we conclude that NSVE is as effective as SYNE, but at lower concentrations, and that it may be of greater value as a micronutrient source for aquaculture feeds.