Submitted to: Book of Abstracts World Aquaculture Society
Publication Type: Abstract Only
Publication Acceptance Date: August 5, 2003
Publication Date: March 1, 2004
Citation: Gaylord, T.G., Davis Jr, K.B., Rawles, S.D. The dietary tryptophan requirement of hybrid striped bass (morone chrysops x m. saxatilis). Book of Abstracts World Aquaculture Society. 2004. [abstract] 217. Technical Abstract: Only four of the 10 essential amino acids have been quantified for hybrid striped bass: arginine, lysine, threonine and the total sulfur amino acids. We hypothesized that the tryptophan (TRP) requirement of hybrid striped bass could be estimated from a four- or five-parameter saturation kinetics model (SKM) of tissue responses to a suitable range and number of dietary supplementation. The basal diet was formulated to contain 35% protein with 10% supplied by intact protein (fishmeal) and the remainder by a crystalline amino acid mixture that mimicked the amino acid profile of hybrid striped bass muscle, without TRP, when added to the intact protein. The basal diet, containing 0.1% endogenous TRP, was supplemented with increasing levels of TRP for a total of 15 diets containing 0.1%, 0.13, 0.16, 0.19, 0.22, 0.25, 0.28, 0.31, 0.34, 0.37, 0.4, 0.5, 0.6, 1.0, and 1.4 % dietary TRP. Diets were fed twice daily to near satiation to aquaria (60-L) containing 10 fish each (42 g ave.fish weight). Mortality of fish receiving the basal diet (0.1% TRP) was 60% after 5 wk, while the remaining 4 fish were in poor health and subsequently sacrificed for compositional analyses. Survival of fish receiving the 0.13% TRP diet had declined to 70% by the termination of the trial. Survival in all other treatments was 100%. Fish weight gain was 100% or greater for fish receiving diets containing 0.16% TRP or more. HSI, MR and IPF also were responsive to dietary TRP concentration. Non linear regressions of response data indicate that the SKM fits the data well. The TRP requirement of hybrid striped bass will be presented.