Fish meal replacement studies

While fish oils are rich in omega-3 polyunsaturated
fatty acids, vegetable oils mainly contain omega-6 polyunsaturated fatty acids
and saturated fatty acids.  These differences may modify the metabolic
processes involved in lipid storage.

However, INRA showed that the total
replacement of fish oil by a mixture of vegetable oils had no effect on either
growth or muscle lipid levels in the trout. However, feed containing the
mixture of vegetable  oils caused a reduction in the levels of plasma
cholesterol and circulating LDL (low density lipoprotein, transport proteins)
and in the expression of the LDL receptor gene in the liver and adipose tissue.

A total replacement of fish
oil by a mixture of vegetable oils is thus possible in the trout, although
further studies are necessary to clarify the mechanisms responsible for the
cholesterol-lowering effect of vegetable
oils.