COBIA (Rachycentron canadum)

largely unaffected by partial replacement of FO with SO: feed intake and final weight were reducedonly in the 0% FO dietary treatment. Fillet total lipid fatty acid (FA) composition differed amongthe dietary treatments, closely approximating dietary FA profile. As increasing amounts of FO werereplaced, SO-associated FA became enriched within the fillet lipid at the expense of FO-associatedFA. Fillet lipid classes were associated with a particular FA signature, regardless of dietary FAprofile. SO can replace a substantial amount of dietary FO; however, juvenile cobia appear toexhibit a nominal requirement for intact long-chain polyunsaturated FA. Therefore, aggressive FOreplacement may result in essential fatty acid deficiencies unless the feeds can be amended withalternative sources of these essential nutrients.265. Trushenski, J., Schwarz, M.H., M.H, Pessoa, W.V.N., Mulligan, B., Crouse, C., Gause, B.,Yamamoto, F. & Delbos, B. (2013). Amending reduced fish-meal feeds with marine lecithin, butnot soy lecithin, improves the growth of juvenile cobia and may attenuate heightened responses tostress challenge. Journal of Animal Physiology and Animal Nutrition, 97(1), 170-180.Sparing of marine resources in aquafeeds can be environmentally and economically advantageous;however, fish meal (FM) replacement can affect the production performance and physiologicalcompetence. Phospholipids are increasingly understood to be involved in maintaining growth andvigour in fish and may be deficient in reduced FM formulations. Accordingly, we evaluated thegrowth and stress tolerance of juvenile cobia fed typical (50% FM) or reduced FM feeds (12% FM)with or without phospholipid amendment [1% marine lecithin (12% FM + Marine PL) or soylecithin (12% FM + Soy PL)] for 6 weeks in triplicate tanks (N = 3) in a recirculation aquaculturesystem. The 50% FM feed yielded significantly superior growth and growth efficiency incomparison with the 12% FM and 12% FM+ Soy PL feeds, but the 12% FM+ Marine PL feedyielded comparable results to 50% FM feed. A low-water stress challenge induced elevated plasmaglucose, cortisol and lactate levels in all treatments. However, a significant interaction (diet - stress)effect suggested a lesser cortisol response among fish fed the 12% FM+ Marine PL and 50% FMdiets. These findings demonstrate that growth performance and, perhaps, resilience of cobia raisedon reduced FM feeds may be improved by the addition of marine-origin phospholipid to the diet.266. Trushenski, J., Woitel F., Schwarz, M.H. & Yamamoto, F. (2013). Saturated fatty acids limit theeffects of replacing fish oil with soybean oil with or without phospholipid supplementation in feedsfor juvenile cobia. North American Journal of Aquaculture, 75(2), 316-328.The high cost and limited availability of fish oil makes plant-derived lipids attractive for aquafeedmanufacturing, but replacing fish oil with these lipids can result in long-chain polyunsaturated fattyacid (LC-PUFA) deficiencies. Fatty acid metabolism, specifically the efficiency of LC-PUFAutilization, may be influenced by the dietary saturated fatty acid (SFA) content versus that of C 18polyunsaturated fatty acids (PUFAs). We assessed the growth and tissue composition of CobiaRachycentron canadum (55.3 ± 0.2 g initial weight [mean ± SE]; 10 fish/tank, 3 tanks/diet) fed diets( 49% protein, 10% lipid) containing fish oil; 22:6(n-3)–amended standard, partiallyhydrogenated, or fully hydrogenated soybean oil; and these same soybean oils supplemented withsoybean lecithin for 8 weeks. Although survival (range = 97–100%), final weight (160–189 g), andfeed conversion ratio (1.40–1.52) were unaffected by diet, differences were observed in weight gain(185–241%), specific growth rate (1.87–2.19% body weight/d), and feed intake (2.94–3.44% bodyweight/d). Significant effects of soybean oil type on final weight, weight gain, feed conversionratio, specific growth rate, and feed intake were noted, with standard soybean oil generallyoutperforming the other soybean lipids when oil types were pooled across phospholipidsupplementation treatments, whereas phospholipid supplementation had no significant effect on anyof the performance measures. Differences in dietary fatty acid profile yielded differences in tissuecomposition. Feeding standard soybean oil resulted in the most greatly modified profiles, whereasthe profiles of fish fed fully hydrogenated, completely saturated soybean oil were most similar tothose of the fish oil–fed fish. The magnitude of profile change was greatest in the liver and fillettissues and smallest in the eye and brain tissues. Although further research is necessary todemonstrate whether SFA-rich lipids can effectively reduce the LC-PUFA requirements of Cobia, itis clear that SFA-rich oils offer a strategic advantage in minimizing the effects of fish oilreplacement on tissue fatty acid profile.267. Turner, J.P. & Rooker, J.R. (2005). Effect of dietary fatty acids on the body tissues of larval andjuvenile cobia and their prey. Journal of Experimental Marine Biology and Ecology, 322(1), 13-27.Polyunsaturated fatty acids (PUFAs) have been used as biomarkers in pelagic ecosystems althoughprevious studies have failed to quantify the timing of conservation of dietary PUFAs in pelagic82