Effects of Nutritional Supplements Phosphatidylcholine and Beta-Carotene on Growth and Selected Stress and Immune Parameters in Nile Tilapia, Oreochromis Niloticus (L.)
Dietary supplements phosphatidylcholine and β-carotene, a dimer of vitamin A have been shown have positive effectson a variety of physiological and immunological parameters in humans and other vertebrates. Previous studies have demonstrated that these neutraceuticals enhance growth of Nile tilapia reared under optimal temperature. However, in those studies specially formulated diets were used. Given that tilapia is a commercially important fish, unlike previous studies we wanted to examine the effects of adding these supplements directly to the commercially available basal diet. Since weight gain can be accompanied by poor health and overdose of vitamin A can be toxic we examined condition factor, which is an indicator of overall health. Effects of these neutraceuticals on stress parameters such as blood glucose levels and hematocrit as well as on immune function as measured by macrophage phagocytic activity were also examined. All experiments in our study were conducted on tilapia grown under optimal temperature (28±2℃). Our experiments showed that both phosphatidylcholine and β-carotene supplemented diets significantly enhanced fish growth compared to basal diet.However, there were no significant differences in condition factor and stress or immune parameters. Thus it was apparent that fish remain healthy and stress free. Furthermore, there was no negative effect on immune function. These data collectively suggest that addition of phosphatidylcholine and β-carotene to commercially available basal diet used in this study can be used in tilapia aquaculture to enhance fish growth. This information can also help producers of commercial feed in improving feed composition.