Effects of dietary fatty acids on the respiratory and cardiovascular physiology of fish

In animals, the composition of fatty acids (FAs) in body pools reflects die tary intake. This paper reviews evidence that the manipulation of tissue li pids of farmed fish, by feeding them different natural oils: can have signi ficant effects on their respiratory and cardiovascular physiology. Sturgeon and eels with tissue lipids rich in highly unsaturated FAs of the n-3 seri es (n-3HUFAs, accumulated from dietary menhaden oil) had significantly lowe r metabolic rates than fish with tissues rich in saturated FAs (SFAs, from coconut oil), although they grew equally well. In sturgeon, the difference in metabolism influenced tolerance of hypoxia. Degrees of hypoxia that depr essed oxygen uptake and spontaneous activity in fish rich in SFAs had no su ch effects on fish rich in n-3HUFAs. In the isolated sturgeon heart working in vitro, reduced oxygen supply depressed the performance of hearts with l ipids rich in SFAs but not that of hearts rich in n-3HUFAs. In salmon fed d iets with graded mixtures of menhaden and canola oils, there was no relatio nship between tissue n-3HUFA content (from menhaden oil) and any measured a spect of swimming performance, but a linear relationship between maximum su stainable swimming speed and muscle oleic acid levels (from canola oil). Su ch exploratory studies indicate that an animal's responses to its environme nt may be profoundly affected by the oils and FAs it consumes in its diet. (C) 2001 Elsevier Science Inc. All rights reserved.