IMPROVEMENT OF NUTRITIONAL QUALITY OF CULTURED SEA BREAM (Sparidentex hasta) MUSCLE BY PREHARVEST FEEDING TECHNIQUE USING FINISHER FEEDS
The aim of this study was to improve the muscle and nutritional quality of the cultured sea bream (Sparidentex hasta) to be at par with that of the wild. This aim was achieved by feeding them with finisher feeds with high decosahexaenoic acid (DHA) content at the latter part of the grow-out stage so that they become equally acceptable as the wild to the consumers. The highest dietary levels of DHA in finisher feeds were chosen to match the level of DHA in wild sea bream muscle in the pre-spawning season when DHA is in its highest level. The level of DHA in the finisher feeds were maintained by incorporating high DHA tuna oil to a best performed grow-out diet for sea bream. A grow-out feed was used from the beginning until the end of the trial was considered as the control (Diet 1). Diet 2 and Diet 3 were formulated to contain 9.0 and 10.5% DHA, respectively, by incorporating high DHA tuna oil into a sea bream grow-out diet. Diet 4 was a commercial finisher feed from a feed company (Skretting, Italy). The experiment was carried out with grow-out sea bream (202.9 ± 3.6g) using a flow-through system consisting of 12 1-m3 circular fiber glass tank. The stocking density was 20 fish/m3, and the fish were hand fed twice daily at satiation level. All the fish were fed with the same grow-out feeds (Diet 1) from the start of the experiment for 4 months and then, the finisher feeds were fed for another two months. The results showed that all the finisher diets resulted in significantly (P < 0.05) better growth performance, feed utilization and higher muscle eicosapentaenoic acid (EPA) and DHA content in sea bream compared to those fed the control diet. The DHA and EPA in fish fed finisher diets were also higher than those of the whole year average DHA and EPA content of wild sea bream. An organoleptic comparison of muscle quality of cultured and wild sea bream showed no significant (P > 0.05) differences between sensory attributes. A study to determine the best time duration for feeding finisher diet showed that 6 weeks of feeding is optimum for assimilation of DHA in fish muscle.