After 112 days on the diets, serum vitamin A and astaxanthin levels in each of the 4
dietary groups were measured (Table 3). Trout fed diets depleted of vitamin A had significantly
(P < 0.001) decreased levels of vitamin A, and whilst the difference in levels of
vitamin A between the supplemented and unsupplemented diets was some 34-fold the
difference in the serum vitamin A levels of fish on these diets was some 8-lo-fold by this
time. As expected, serum astaxanthin was detected in fish fed diets supplemented with
astaxanthin (diets A+Ax+ and A-Ax+) but not from fish fed diets lacking astaxanthin
(diets A+Ax- and A-Ax-). However, supplementing the vitamin A deficient diet with
astaxanthin (diet A-Ax+) had no significant effect on serum vitamin A levels.