Dietary lycopene alters the expression of antioxidant enzymes and modulates the blood lipid profile of pigs

Abstract

Lycopene has the highest antioxidant activity among carotenoids due to its high number of conjugated double bonds; thus, it can be used in pig diets to look for improvements in growth performance and health status, eliminating or preventing the formation of free radicals. Therefore, the aim of the present study was to investigate the effects of dietary lycopene on the growth performance, the gene expression of antioxidant enzymes and blood lipid profile of finishing pigs. In total, 40 barrows and 40 gilts (Piétrain × Landrace × Large White) were used, averaging 75.04 ± 1.6 kg of initial bodyweight. Pigs were distributed in a 2 × 5 factorial arrangement, consisting of two genders (male and female) and five dietary levels of lycopene (0, 12.5, 25.0, 37.5 and 50.0 mg/kg of diet) supplemented for 28 days. It was observed that gilts presented with average daily feed intake (P = 0.001) being lower and the gain:feed ratio (P = 0.001) higher than for barrows. Increasing dietary lycopene concentration provided a linear decrease in the gene expression of the enzymes superoxide dismutase (SOD1; P = 0.018) and catalase (P = 0.001) in the liver of gilts. The gilts showed a lower gene expression than did barrows for SOD1 gene (P = 0.001) receiving 50.0 mg lycopene/kg of diet and for catalase gene (P = 0.001) receiving of 0, 12.5 and 50.0 mg lycopene/kg of diet. Glutathione peroxidase showed a lower expression (P = 0.001) for gilts than for barrows. Total cholesterol, low-density lipoprotein (LDL) and LDL:high-density lipoprotein (HDL) ratio decreased (P = 0.001) as lycopene concentration increased in the diet. Increasing dietary lycopene in pig diets improved the lipid profile of the blood plasma, providing an increase in the concentration of high-density lipoprotein (HDL; P = 0.001). Gilts had greater plasma concentrations of urea (P = 0.001) and triglycerides (P = 0.001) and lower concentrations of HDL (P = 0.001), LDL (P = 0.001) and a lower LDL:HDL ratio (P = 0.004) than did barrows. Dietary lycopene up to 50 mg/kg does not affect the growth performance of pigs, acting as a potent modulator of the lipid profile and also reducing the plasma concentrations of total cholesterol and low-density lipoproteins, while increasing the high-density lipoproteins. In addition, lycopene also reduces the gene expression of superoxide dismutase and catalase enzymes in the liver of gilts.