Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2007
Publication Date: February 10, 2008
Citation: Rawles, S.D., Gaylord, T.G. 2008. The dietary branched chain amino acid requirements of hybrid striped bass(Morone chrysops x M. saxatilis). In: Proceedings of the Striped Bass Grower's Association Industry. Aquaculture America Conference, February 9-12, 2008, Lake Buena Vista, Florida. 2008 CDROM. Technical Abstract: The requirements for branched chain amino acids (BCAAs) are unknown in hybrid striped bass and necessary for formulating efficient and nutritious diets. Moreover, the dietary balance among these three amino acids can substantially influence the performance of meat animals fed those diets. The dietary requirements for leucine (LEU), isoleucine (ILE), and valine (VAL) were determined in juvenile hybrid striped bass (5 g initial weight) in three dose-response trials. Basal diets were formulated to contain 35% protein, 13% lipid, and 3.8 Kcal/Kg available energy and matched the amino acid profile of 35% hybrid striped bass muscle with the exception of the BCAA of interest. A series of 13-14 diets were then formulated to contain increasing concentrations of each BCAA of interest. Each diet series contained about 0.5 to 4.0 g amino acid per 100 grams of diet or about 1.5 to 11 g amino acid per 100 grams of protein. Each diet was fed once daily to a single, randomly assigned tank containing ten fish. Feed intake was measured daily in order to estimate maintenance requirements. Retention efficiencies were determined by comparing body composition before and after the feeding trials. Performance and compositional measures were modeled by nonlinear saturation kinetics models (SKMs) and requirements for each BCAA were estimated as the R95 – the amino acid concentration which yielded 95% maximum response. Complete mortality occurred within 3-6 weeks when diets contained less than or equal to 0.88 g LEU (= 2.5% of dietary protein), 0.53 g ILE (= 1.5% of dietary protein), or 0.72 g VAL (= 2.0% of dietary protein) per 100 g diet. Plots of feed efficiency (FE) were extremely consistent, whereas weight gain was more variable, with respect to diet over the 8-wk trials. Preliminary requirement estimates based on feed efficiency increased at each 2-wk sampling up to 6 or 8 wks. Based on feed efficiency, hybrid striped bass requirements for branched chain amino acids are 1.4 - 1.5 g LEU (4.0 - 4.3% of dietary protein), 0.9 - 1.0 g ILE (2.6 - 2.9% of dietary protein), and 0.8 - 1.1 g VAL (2.3 - 3.1% of dietary protein) per 100 g diet. These data are consistent with current BCAA requirements in other carnivorous fish and will increase the efficiency of both research and commercial diet formulations. Moreover, these data are critical for accurate exchanges of dietary protein sources in aquafeeds and for efforts aimed at reducing the dependence on ocean-derived fishmeal.