Fish oil replacement in rainbow trout diets and total dietary PUFA content: I) Effects on feed efficiency, fat deposition and the efficiency of a finishing strategy

More Judicious Use of Fish Oil in Cobia Feeds: II. Effects of Graded Fish Oil Sparing and Finishing

“…Specifically, differences in fillet LC-PUFA content persisted through harvest, and there was no significant effect of time (i.e., the duration of finishing) on fillet LC-PUFA level; in addition, C 18 PUFA levels increased significantly in all fillet and eye tissues and in some liver tissues during finishing. It has been suggested that C 18 PUFAs are somewhat resistant to change during finishing (Thanuthong et al 2011;Trushenski et al 2011b), but we believe that in the present case these trends are more likely related to differences in fatty acid composition among different batches of finishing feed (Table 3). Batches of the finishing feed were assembled independently and at disparate times.…”

“…The influence of diet on tissue fatty acid profiles in fish has been documented numerous times, with dietary composition affecting tissue composition in a more or less direct manner (Glencross 2009;Palmeri et al 2009;Thanuthong et al 2011;Ng et al 2013) except among fish that are fed SFA-and MUFA-rich lipids (Trushenski et al 2008a(Trushenski et al , 2008b(Trushenski et al , 2011a(Trushenski et al , 2011cLaporte and Downloaded by [University of Texas Libraries] at 06:38 27 September 2014 TABLE 6. Fatty acid composition (g/100 g of fatty acid methyl esters), coefficient of distance (Djh) values, and total lipid content (% dry matter) of postfinishing fillet tissue samples from Cobias in the four treatment groups (feeds are defined in Table 1).…”

The effect of total replacement of fish oil with DHA-Gold®and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant-based diet

“…Higher dietary concentrations of 18:3n-3 and 18:2n-6 as compared to fillet concentrations is supported by earlier findings in rainbow trout (Thanuthong et al 2011) and in salmon (Stubhaug et al 2006(Stubhaug et al , 2007. The authors found that both fatty acids are abundantly used for fatty acid b-oxidation when present in high quantities in fish diets.…”

“…Although it has been suggested that 18:3n-3 is a preferred substrate for the elongases over that of 18:2n-6 and that the enzymes activities are substrate-dependent, it is difficult to ascertain if in the current study elongase was insufficient or that the high contents of 18:2n-6 and 18:3n-3 in the diets prevented the activities of these enzymes. The concentration of 18:3n-3 in the fillets of fish fed the PO diet was not affected by supplementing the PO diet with DHA-G, but fillet 18:2n-6 and 20:4n-6 levels decreased with increased dietary inclusion of DHA-G. As adequate dietary DHA was supplied, it is possible that there was no need for the D-6 desaturase to mobilize 18:2n-6 and 18:3n-3 for elongation as well as subsequent in vivo desaturation to 22:6n-3 (Thanuthong et al 2011). Substrate availability does not explain the low amounts of arachidonic acid detected in the fillets of fish fed FO or DHA- Figure 1 Paired comparison sensory evaluation of fillets from rainbow trout fed a plant-based diet containing different lipid sources.…”

“…For this reason, total replacement of fish oil with vegetable oil for many species, including rainbow trout, is still considered impossible due to the resultant modification of the fatty acid composition of cultured fish. Previous studies have recommended the use of diets containing fish oil during a finishing period to restore the fatty acid composition of the fish previously fed the alternative lipid sources (Mourente & Bell 2006;Trushenski & Boesenberg 2009;Thanuthong et al 2011). However, restoration of muscle fatty acid in carnivorous species requires large quantities of fish oil due to the high dietary levels needed for market size fish (Jobling 2004;Trushenski & Boesenberg 2009).…”