The Study of Fillet Quality and the Growth Performance of Rainbow Trout (Oncorhynchus mykiss) Fed with Diets Containing Different Amounts of Vitamin E

Abstract

This study investigated the effects of adding different amounts of α-tocopherol acetate (ATA, 100, 300 and 500 mg kg-1 diet), to a commercial feed on the growth performance, body composition and vitamin E levels in the fillet of rainbow trout (initial weight = 131.3 ±1.0 g) over a period of 58 days. In the analyses of trial diets, average rates of 46.6 ±0.4% crude protein, 13.9±0.1% lipid, and 130.2 (Diet 1), 370.5 (Diet 2) and 580.9 (Diet 3) mg kg-1 diet of vitamin E were found, respectively. The results of the 58-day feeding study were that the specific growth rate and condition factors of the fish were not affected by diets containing different levels of ATA (P>0.05). Fish that were fed 370.5 and 580.9 mg kg-1 ATA diets had significantly lower feed conversion ratios than fish that were fed a 130.2 mg kg-1 ATA diet (P<0.05). The diets containing different levels of ATA did not affect the fillet's proximate composition, viscerosomatic index, or hepatosomatic index, except for the fillet and liver lipid content. The fillet and liver lipid content and hepatosomatic index of the fish increased with growth. The vitamin E levels in fish fillet reflected dietary ATA levels. The increase in dietary ATA affected ATA accumulation in the fish fillets and whole-body lipids. The high level of ATA in the fish flesh indicated good flesh quality. These results showed that fish on Diets 2 and 3 had significantly better FCR than those on Diet 1, and fish on Diet 3 had significantly higher flesh quality than the others.