Fatty acid profile of fish following a change in dietary fatty acid source: model of fatty acid composition with a dilution hypothesis

Abstract

The fatty acid (FA) content of fish is generally said to reflect fatty acid composition of the diet. In fact, incorporation of FA into tissues is modulated by various metabolic factors, and final composition will depend upon the initial FA content, cumulative intake of dietary fatty acids, growth rate and duration. Analysis of time course of changes in FA composition should be easier with animals having different initial FA profiles, which are subsequently fed a diet with the same FA composition. Data from two studies, one with brown trout and another with turbot were used. Fish were first fed with diets containing one of three different oils (soybean oil (SO), linseed oil (LO) and fish oil (FO)), and subsequently fed the same fish oil-based diet (washout period). If we suppose a model fish having the same initial composition as those fed vegetable oil and which incorporate fatty acid in the same way as the control fish always fed fish oil, we may compute a model of dilution of initial fatty acid content with increasing growth and absolute fat deposition. Experimental data can be compared with a reference fatty acid profile given by this model for the same fatty acid increase. Application of the model to experimental data shows that while muscle neutral lipid (NL) FAs roughly follow this dilution model, those of muscle polar lipids (PL) undergo much faster changes than model values based on increase of total polar lipid quantities. Among observed differences between the model and experimental values, DHA is of particular interest as this fatty acid displays lower change rates (significant in turbot neutral lipids) than expected in contrast to other fatty acids.

Tuna Nutrition and Feeds: Current Status and Future Perspectives

“…Decreased levels of the n-3 lc-PUFA, EPA and DHA, and increased levels of LOA and LNA can compromise the nutritional quality of the flesh . For that reason, some studies have investigated the use of "finishing diets" containing fish oil to restore levels of n-3 lc-PUFA in the flesh (Bell et al, 2003a,b;Bell et al, 2004;Robin et al, 2003;Caballero et al, 2004;Izquierdo et al, 2005;Mourente et al, 2005Mourente et al, , 2006Torstensen et al, 2005). The large tunid market demands very high flesh quality standards suggesting that major changes in flesh fatty acid composition in farmed tuna may not be acceptable.…”

“…It is debatable that a finishing diet strategy could be successful with fish with a very large market size. At lower inclusion levels, dietary vegetable oils have correspondingly less impact on flesh fatty acid compositions (Robin et al, 2003). Therefore, an alternative to finishing diets could be the use of lower levels of fish oil substitution, particularly if the vegetable oil and fish oil blends used are carefully chosen to limit lc-PUFA reduction in the flesh (Torstensen et al, 2004).…”

Characterization of Fish Oil Extracted from Fish Processing By-products

“…These fishes are among the best sources of PUFA. However, the fish oil contents and fatty acid compositions of these fishes are not constant (6), and great variations are reported, in terms of fat content and fatty acid composition, for various marine organisms (7)(8)(9).…”

Marginal efficiencies of long chain-polyunsaturated fatty acid use by barramundi (Lates calcarifer) when fed diets with varying blends of fish oil and poultry fat

“…The fish in this study achieved a minimum 2.5-fold increase in weight over the twelve week study period. Experimental duration is of particular interest in the realm of fatty acid nutrition as the increasing use of alternative oils has an definitive influence on flesh quality (Robin et al, 2003). The NRC (2011) suggest that 300% or a 3-fold increase in weight should be respected and a range of other studies suggest different methods of assessment (Glencross et al, 2003;Jobling, 2004;Morton et al, 2014;Robin et al, 2003).…”