COBIA (Rachycentron canadum)

effects upon final product quality, which may have implications in terms of cobia processing anddevelopment of industrial products.239. Lunger, A.N., McLean, E., Gaylord, T.G. & Kuhn, D. & Craig, S.R. (2007). Taurinesupplementation to alternative dietary proteins used in fish meal replacement enhances growth ofjuvenile cobia (Rachycentron canadum). Aquaculture, 271(1-4), 401-410.Two separate 8 week feeding trials were conducted to examine the impacts of fish mealreplacement with an organically certifiable yeast-based protein source with and withoutsupplementation of methionine, tryptophan, and taurine to diets for juvenile cobia. In the first trial,diets were formulated to contain 41% crude protein and 13% lipid, and a yeast-based proteinreplaced fish meal at 50 and 75% of dietary protein with and without supplemental taurine at0.5 g/100 g dry diet. The control diet contained 100% herring fish meal. Methionine and tryptophanwere added to all diets except the control to resemble the amino acid profile of fish meal. Resultsfrom this study indicated that fish fed diets supplemented with taurine exhibited significantly higherweight gain and better feed efficiencies than all other fish. Diet significantly impacted biologicalindices such as muscle ratio (MR), visceral somatic index (VSI), and hepatosomatic index (HSI).The 75% yeast-based protein diet without taurine returned the lowest MR values and the highestVSI and HSI values. In the second trial, diets were formulated to contain 43% crude protein and11% lipid, with the control diet containing 100% herring fish meal and the same yeast-based proteinreplacing fish meal at 50, 75, and 100% of dietary protein. All diets except the control weresupplemented with taurine at 0.5 g/100 g dry diet. Results from this study indicated that increasingamount of yeast-based protein led to decreased weight gains and feed efficiencies regardless oftaurine supplementation. However, weight gain and feed efficiencies did increase when comparedto a previous study [Lunger, A.N., McLean, E., Craig, S.R., 2007. The effects of organic proteinsupplementation upon growth, feed conversion and texture quality parameters in juvenile cobia(Rachycentron canadum). Aquaculture 264, 342–352] using identical diet formulations except fortaurine supplementation. MR values tended to decrease while VSI and HSI values tended toincrease with increasing fish meal replacement. It is obvious from the results from both of thepresent studies that taurine supplementation does have a significant impact on growth and feedefficiency of juvenile cobia when they are fed diets containing high levels of plant-based proteins asreplacements for fish meal. Additionally, alternate proteins, especially those of plant and yeastbasedorigin can be incorporated at very high levels in diets for cobia with proper amino acidsupplementation.240. Luo, Y., Ai, Q., Mai, K., Zhang, W., Xu, W. & Zhang, Y. (2012). Effects of dietary rapeseedmeal on growth performance, digestion and protein metabolism in relation to gene expression ofjuvenile cobia (Rachycentron canadum). Aquaculture, 368-369, 109-116.A 60-day feeding trial in seawater floating cages (1.5 x 1.5 x 2.5 m) was conducted to investigatethe effects of dietary rapeseed meal (RM) levels on feed intake, growth, survival, digestion andprotein metabolism in relation to gene expression of juvenile cobia (initial body weight 94.6 g).Five isonitrogenous (crude protein 450 g kg -1 of dry matter) and isoenergetic (20 kJ g -1 ) practicaldiets were formulated by replacing 0 (the control), 125, 250, 375 and 500 g kg -1 fish meal proteinwith RM protein. Each diet was randomly fed to triplicate groups of fish, and each cage wasstocked with 20 fish. Fish were fed twice daily (06:00 and 18:00) to apparent satiation. The survivalranged from 96.7 to 98.3%, and no significant difference was observed among dietary treatments(P>0.05). With increasing dietary RM levels, feed intake (FI), specific growth rate (SGR) and feedefficiency (FE) decreased. Fish fed the diet with 250 g kg -1 or more protein from RM hadsignificantly lower SGR and FE than the control group (P0.05). Apparent digestibilitycoefficients (ADCs) of dry matter (DM), crude protein and energy significantly decreased withincreasing dietary RM levels (P