FACTORIAL EXPERIMENT TO DETERMINE INFLUENCE OF FISH-PROTEIN AND FISH OIL ON SERUM AND LIVER LIPIDS IN RABBITS

Rabbits were fed purified diets consisting of casein (CA), fish protein (FP), and soy protein (SP) combined with MaxEpa oil (ME) or com oil (CN) to determine the effects of dietary protein and lipid sources on serum total, lipoprotein, and hepatic lipid levels. Dietary proteins and lipids exerted significant (p < 0.05) separate effects on serum total cholesterol (TC) (p < 0.005), very-low-density lipoprotein cholesterol (VLDL-C) (p < 0.001), and high-density lipoprotein cholesterol (HDL-C) (p < 0.001), whereas only dietary proteins significantly affected low-density lipoprotein cholesterol (LDL-C) (p < 0.001) and the LDL-C/HDL-C ratio (p < 0.05). Hence, FP induced serum TC (233 mg/dl), VLDL-C (22 mg/dl), and LDL-C (151 mg/dl) intermediary to hypercholesterolemic CA (TC, 319 mg/dl; VLDL-C, 57 mg/dl; LDL-C, 204 mg/dl) and cholesterol-lowering SP (TC, 129 mg/dl; VLDL-C 19 mg/dl; LDL-C, 84 mg/dl). The twofold rise in HDL-C on feeding FP (35 mg/dl), compared with CA (20 mg/dl) and SP (16 mg/dl), resulted in a drop in LDL-C/HDL-C to a level similar to that of SP groups. The cholesterol-lowering action of ME (188 mg/dl), in contrast to CN (266 mg/dl), was reflected mainly in VLDL (ME, 15 mg/dl; CN, 50 mg/dl) but also in HDL (ME, 16 mg/dl; CN, 31 mg/dl) fractions. Compared with CN, the significant (p < 0.05) ME-induced rise in serum and VLDL triglycerides was accompanied by a significant (p < 0.001) drop in lipoprotein lipase activity. Our results indicate that both FP and ME are separately involved in the changes in lipoprotein profile associated with fish intake in the rabbit.