|Rawles, Steven - Steve|
Submitted to: Book of Abstracts World Aquaculture Society
Publication Type: Abstract only
Publication Acceptance Date: 11/24/2003
Publication Date: 5/1/2004
Citation: Gaylord, T.G., Rawles, S.D. Determination of the essential fatty acid requirement of sunshine bass (morone chrysops x m. saxatilis) with respect to the level of dietary lipid. Book of Abstracts World Aquaculture Society. 2004. [abstract] p.491. Interpretive Summary:
Technical Abstract: Current trends in sunshine bass (Morone chrysops X M. saxatilis) culture are to feed diets of higher lipid content in order to spare protein utilization as an energy yielding substrate. The dietary requirement of hybrid striped bass for essential fatty acid (EFA), however, was determined using diets containing 5% total lipid. It is uncertain whether hybrid striped bass requirements for eicosapentenoic acid (EPA) + docosahexanoic acid (DHA) are met when fed diets containing higher levels of fat. Therefore, a 7-wk feeding trial was undertaken to assess the requirements of sunshine bass when fed diets containing 5, 10 or 15% dietary lipid. Isonitrogenous, isocaloric diets were supplemented with levels of EPA+DHA at 0.1, 0.6, 0.85 and 1.1% of the diet when diets contained 5% lipid, 0.1, 0.6, 1.1, 1.6, and 2.6% of the diet when diets contained 10% lipid, and 0.1, 0.85, 1.6, 2.1, and 3.6% of the diet when diets contained 15% lipid. The ratio of EPA:DHA in the diets was held constant (1:3). Sunshine bass with an initial average weight of 7.7 g were stocked into 78-L aquaria receiving flow-through well water maintained at 26 C. Each treatment was fed to three replicate aquaria containing 10 fish each. Increasing the dietary lipid level above 5% had a positive effect on weight gain. Weight gain was improved from an average 328% at 5% dietary lipid to 419 and 424% for fish consuming the 10 and 15% lipid diets, respectively. Feed efficiency also improved from 0.46 at 5% dietary lipid to 0.57 and 0.59 at 10 and 15% dietary lipid, respectively. Non-linear regressions of response variables with respect to dietary EFA level indicate that the EFA requirement of sunshine bass fed diets containing 5% lipid may be as low as 0.5 -0.7 % of diet; whereas the requirement when fed diets containing 10 to 15 % dietary lipid was approximately 1% of diet.