A cold manipulation of rainbow trout (Oncorhynchus mykiss) at eyed-stage has few impacts on hepatic lipid metabolism in juveniles

Metabolic programming through thermal manipulation in the early stages of life has been observed in animals such as birds and fish. Here, we analysed two lines of rainbow trout selected for their lipid content, which have been shown to exhibit divergent regulation of lipid metabolism. The eyed eggs of the fat and lean lines, which were produced in the seventh generation of selection, were subjected to cold manipulation for 15 days at 3 °C. The effect of this stimulus on lipid and cholesterol metabolism in the livers of juvenile fish was then investigated later in life. Although the differences between the two lines were confirmed with regard to lipid metabolism (beta-oxidation, lipogenesis, and cholesterol metabolism), no major differences were observed in relation to the early cold manipulation with respect to metabolic and growth levels. Indeed, our data showed that early cold manipulation at the eyed stage has no adverse effects on fish performance or metabolism, confirming that this common aquaculture practice has no drastic consequences for fish rearing.