Modulation of arachidonate and docosahexaenoate in Morone chrysops larval tissues and the effect on growth and survival

Abstract

The extent to which extreme dietary levels of arachidonate (AA) and/or docosahexaenoate (DHA) modulate lipid composition in the body tissues and consequently affect growth and survival in freshwater Morone larvae species was examined. White bass, M. chrysops, larvae (day 24-46) were fed Artemia nauplii enriched with algal oils containing varying proportions of AA and DHA (from 0 to over 20% the total fatty acids). Growth was significantly reduced (P< 0.05) in larvae fed a DHA-deficient Artemia diet. Increases in dietary levels of AA also were associated with a significant growth reduction. However, the inhibitory effect of AA on larvae growth could be suppressed by the dietary addition of DHA (at a level of 21.6% of the total fatty acids in enrichment lipids). Larval brain + eyes tissue accumulated over 10 times more DHA than AA in its structural lipids (phosphatidylcholine, phosphatidylethanolamine) at any dietary ratio. In contrast, DHA accumulation, as compared to AA, in gill lipids declined considerably at higher than 10:1 DHA/AA tissue ratios. DHA and eicosapentaenoic acid (EPA) contents in brain + eyes tissue were most sensitive to competition from dietary AA, being displaced from the tissue at rates of 0.36 +/- 0.07 mg DHA and 0.46 +/- 0.11 mg EPA per mg increase in tissue AA, and 0.55 +/- 0.14 mg AA per mg increase in tissue DHA. On the other hand, AA and EPA levels in gill tissue were most sensitive to dietary changes in DHA levels; AA was displaced at rates of 0.37 +/- 0.11 mg, whereas EPA increased at rates of 0.68 +/- 0.28 mg per mg increase in tissue DHA. Results suggest that balanced dietary DHA/AA ratios (that allow DHA/AA ratios of 2.5:1 in brain + eyes tissue) promote a high larval growth rate, which also correlates with maximal regulatory response in tissue essential fatty acids.

Influences of dietary n−3 long‐chain PUFA on body concentrations of 20∶5n−3, 22∶5n−3, and 22∶6n−3 in the larvae of a marine teleost fish from Australian waters, the striped trumpeter (Latris lineata)

“…Similarly, Izquierdo et al (19) observed increased levels of 22:5n-3 in Japanese flounder when dietary 22:6n-3 was low. An increase in 22:5n-3 in the combined brain and eyes of white bass (Morone chrysops) that was inversely related to dietary (Artemia) 22:5n-3 and 22:6n-3 also has been reported (20), as has an accumulation of 22:5n-3 in 22:6n-3-deficient herring, as described previously (9).…”

Linking fatty acids in the diet and tissues to quality of larval southern flounder (Paralichthys lethostigma)

“…Concentrations of DHA in the brain and eyes are higher than concentrations of ARA in the same tissues of Atlantic herring (Clupea harengus L.) and white bass (Morone chrysops) fed diets supplemented with DHA (Bell et al, 1995;Harel et al, 2000). These higher levels of DHA:ARA are specifically in the structural lipids of the brain synaptic membranes and rod photoreceptor outer segments (Harel et al, 2000).…”

“…Through the eicosanoid pathway, ARA is known to promote inflammation, and higher ARA concentrations are believed to act as a stress-alleviating mediator in small rearing tanks or adverse environmental conditions (Connor, 2000;Bell and Sargent, 2003). Multiple studies have shown correlations between dietary ARA levels and growth and survival (Harel et al, 2000;Koven et al, 2001;Bell and Sargent, 2003). It is also important to recognize that the efficacy of DHA and ARA can be modulated by EPA as well as each other and therefore these fatty acids are frequently analyzed and discussed as ratios of one another (Sargent et al, 1999;Harel et al, 2000).…”

“…Multiple studies have shown correlations between dietary ARA levels and growth and survival (Harel et al, 2000;Koven et al, 2001;Bell and Sargent, 2003). It is also important to recognize that the efficacy of DHA and ARA can be modulated by EPA as well as each other and therefore these fatty acids are frequently analyzed and discussed as ratios of one another (Sargent et al, 1999;Harel et al, 2000).…”

The Ocean supplies more EPA and DHA than we can use

“…The distribution of fish populations may be seriously affected, but the importance of sources of omega 3 fatty acids is of concern. Australian and New Zealand scientists are participating in many similar studies [26,27].…”