ESTIMATION OF THE QUANTITATIVE REQUIREMENT FOR DIETARY TAURINE IN FLORIDA POMPANO Trachinotus carolinus JUVENILES
Florida pompano has gained interest as a suitable candidate for the diversification of marine aquaculture. Hence, there is considerable interest in developing species specific feed especially those with high levels of terrestrial protein sources. Although progress in ingredient substitution has been made, performances have been impaired as marine proteins are removed. A growing body of evidence indicates that numerous marine species have a requirement for taurine. Hence, two trials were conducted to study the response of juvenile pompano to graded levels of dietary taurine, from which a requirement level may be estimated. In the first trial, eight diets containing 0.09-1.29% taurine were fed for 58 days, while in the second trial four diets ranging from 0.65-4.16% were fed for 70 days.
In the first trial, a clear dose-response was observed: growth rates (as TGC) significantly improved as dietary taurine increased, until they plateaued around the third diet. Application of a saturation kinetic (SKM) and broken-quadratic (BQM) models yielded requirement estimates and 95% confidence interval (CI) of 0.56% (0.46-0.60%) and 0.28% (0.16-0.39%). In the second trial, no significant differences or correlation in growth performance were observed between the four higher taurine levels. TGC, being independent of body size and water temperature, can be helpful to directly compare two different experiments, and combining data sets. Mathematical models were run again using the combined dataset: the SKM estimated the dietary taurine requirement at 0.54% (95% CI: 0.40-0.68%), while the BQM estimated the requirement at 0.65% (95% CI: 0.37-0.94%). Considering the stability of the SKM estimate and CI overlap between the two models on the combined dataset, it is likely that the initial BQM result was underestimated. Therefore we conclude that dietary taurine is an essential nutrient in Florida pompano, the dietary requirement for which is 0.54-0.65%.