Diets with soybean oil and l-carnitine alter lipid metabolism and improve the growth and reproduction of Rhamdia quelen females

Abstract

This study aimed to evaluate the reproduction, growth, biochemical parameters of blood, hepatic and gonadal redox parameters, hepatic and gonadal histology, and lipid metabolism of silver catfish females (Rhamdia quelen) fed diets containing l-carnitine and different lipid sources. Females were fed for 223 days with eight (08) isoproteic (282 g of digestible protein kg of ration−1) and isoenergetic (13.34 MJ of digestible energy kg of ration−1) diets, containing 0.00, 0.15, 0.45, and 0.75 g l-carnitine kg−1 of feed, and soybean or marine fish oils. Feeding the females diets containing l-carnitine and the different oils resulted in an interactive effect (p < 0.05) that improved the growth and reproduction of the fish. Females fed soybean oil and 0.45 g l-carnitine kg−1 had the highest growth rates, the largest ovaries, and produced the most fertile oocytes, which resulted in the highest hatching rates. These females also showed higher levels of total cholesterol and high-density lipoprotein (HDL) cholesterol, and alterations in the levels of alanine aminotransferase in the blood, in addition to greater activity of hepatic superoxide dismutase and a greater amount of saturated fatty acids in the liver. The ovaries of these females also had the highest amount of docosahexaenoic fatty acid (DHA), highest amount of polyunsaturated fatty acids and fatty acids from the n-3 and n-6 series, and the lowest crude protein content. The interaction between l-carnitine and the lipid source of the diets promoted hepatic protection and regulated lipid metabolism and the fatty acid profile in the liver and ovaries of silver catfish females. The benefits of these interactions improved the growth and reproduction of females fed diets containing soybean oil and 0.45 g l-carnitine kg−1.