EFFECT OF DIET FORMULATION ON THE GROWTH PERFORMANCE AND QUALITY OF TANK REARED CHINESE LONGSNOUT CATFISH (LEIOCASSIS LONGIROSTRIS G躈THER)

A 90 day growth trial was conducted to investigate the effect of different diet formulations on the growth performance and flesh quality of tank reared Chinese longsnout catfish (Leiocassis longirostris Günther). Five diets were formulated: Cont: the control or the normal diet used for the fish; HP: high protein diet; HC: high carbohydrate diet; HL: high lipid diet; HE: high energy diet. The results showed that HC diet effected in negative growth while HP diet showed the highest specific growth rate (SGR) and feed efficiency (FE). Body water content changed in opposite direction of body lipid, and was the highest in fish of HL diet, than HE diet, and the lowest in HP diet. Most of the fish lipid was accumulated in viscera and was higher in HL and HE fed groups, which lead to significant lower yield and caused more amount of muscle maleic dialdehyde (MDA). At the end of feeding experiment, Yellowness (b*) of fish dorsal skin was highest in fish of HC diet, lower in HE diet and lowest in HP diet. Ventral Redness (a*) was highest in HE diet, than HL diet, and the lowest in HP diet. Color showed no significant difference for fresh fillet until after 3d freezing when fillet Yellowness and Whiteness (ΔE)was decreased in the order: HE > HL > HP > Cont, and fillet Redness was decreased in order: Cont > HL > HE > HP. Texture of fresh fillet showed no significant difference except both Hardness and Gumminess was decreased in order: HP > Cont > HL > HE. The experiment showed that lipid was the emphasis among all diet formulations which influenced fish quality of skin color, texture and MDA content during storage by controlling fish body composition. After frozen storage, fillet Hardness, Gumminess, Chewiness and Liquid holding capacity (LHC) decreased but Adhesiveness increased perceptibly, though changes manifested decreased fish quality.