In aquaculture, there are many things that cause animal to stress for example water quality, environment, disease, stocking density, transportation or sampling. Animal requires a lot of energy to manage stress instead of using it for growth and muscle development. Mineral supplementation is one strategy to solve this problem. Chromium and Selenium are interesting trace minerals. Chromium plays a role in carbohydrate, protein, and lipid metabolism. Selenium plays a role in growth, antioxidant, and reproductive functions. Dietary effects of Zinc-L-selenomethionine (Zn-L-Se) and Chromium-L-methionine (Cr-L-met) on growth performance, blood glucose and pH of digestive tract were investigated in juvenile fingerling Red Tilapia (Oreochromis spp). The trial was a CRD with 6 treatments and 20 replications. Fish were fed isonitrogenous and isocaloric diets with 36% crude protein and 8% crude lipid. The 6 treatment groups were T1) Control diet without Zn-L-Se or Cr-L-met supplementation, T2) Control diet supplement with Cr-L-met 0.5 ppm, T3) Control diet supplement with Cr-L-met 1.0 ppm, T4) Control diet supplement with Zn-L-Se 0.3 ppm, T5) Control diet supplement with Zn-L-Se 0.3 ppm and Cr-L-met 0.5 ppm and T6) Control diet supplement with Zn-L-Se 0.3 ppm and Cr-L-met 1.0 ppm. Red Tilapia with an average weight of 35 to 40 g were stocked in 100-L tanks at a density of 1 fish/tank/replicate, with 20 fish/treatment to reduce stress. Fish were fed experimental diets 2 time/day at 3 to 4% body weight for 4 weeks. The results showed that growth performance, in terms of final weight, weight gain, average daily growth and feed conversion ratio were not significantly differences among the treatment groups (P>0.05). Immunity, in terms of superoxide dismutase and glutathione peroxidase differed by treatment (P<0.05) as lysozyme activity and blood glucose showed no significant differences (P>0.05). Digestive tract pH was not affected by treatment (P>0.05). Therefore, Zinc-L-selenomethionine (Zn-L-Se) at 0.3 ppm and Chromium-L-methionine (Cr-L-met) at 0.5 to 1.0 ppm in the diet had no significant effect on growth performance in fingerling Red Tilapia.
Keywords: Chromium, Selenium, Red Tilapia