Fatty acids in extremity tissues of finnish beavers ( Castor canadensis and Castor fiber) and muskrats ( Ondatra zibethicus)

Site-specific differences in fatty acid composition of adipose tissues from Finnish beavers (Castor canadensis and Castor fiber) and muskrats (Ondatra zibethicus) were studied by gas liquid chromatography. In the total lipids of heterothermic extremities the proportions of potentially endogenous (Δ9-desaturated) monoenoic fatty acids were 1.5-fold and those of the saturated fatty acids 0.5-fold the proportions of subcutaneous or inner depots. Thus the role of Δ9-desaturation in the biochemical adaptation of the extremity tissues is discussed. Dietary polyunsaturated fatty acids, with the exception of 18:3ω3 in the beavers, did not accumulate selectively in the extremity tissues. The liver of the muskrat (which also eats fish and mussels) contained high proportions of 22:6ω3, which was a minor component in the beaver (exclusively a herbivore).