Effect of Zinc-L-selenomethionine and Chromium-L-methionine on Growth Performance, Blood Glucose and Digestive Tract pH in Nile Tilapia (Oreochromis niloticus)

Abstract

Dietary effects of Zinc-L-selenomethionine (Zn-L-Se) and Chromium-L-methionine (Cr-L-met) on growth performance, blood glucose and digestive tract pH were investigated in juvenile fingerling Nile Tilapia (Oreochromis niloticus). The trial was a CRD with 6 treatments and 20 replications. Fish were fed isonitrogenous and isocaloric diets with 36% crude protein and 6% lipid. The Control diet (T1) -  was without Zn-L-Se or Cr-L-met addition. Remaining treatments were as follows: T2, - Control + Cr-L-met at 0.5 ppm; T3, - Control + Cr-L-met at 1.0 ppm; T4, - Control + Zn-L-Se at 0.3 ppm; T5, - Control + Zn-L-Se at 0.3 ppm + Cr-L-met at 0.5 ppm; and T6, - Control + Zn-L-Se at 0.3 ppm + Cr-L-met at 1.0 ppm. Nile tilapia with an average weight of 25 to 30 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 2time/day at 3 to 4% body weight for 4 weeks. Growth performance, in terms of final weight, weight gain, average daily growth and feed conversion ratio differed by treatment (P < 0.05). Immunity, in terms of superoxide dismutase, glutathione peroxidase, lysozyme activity, and blood glucose showed no significant differences (P > 0.05). Digestive tract pH was not affected by treatment (P > 0.05). Adding Zinc-L-selenomethionine (Zn-L-Se) at 0.3 ppm and Chromium-L-methionine (Cr-L-met) at 0.5 to1.0 ppm to the diet of fingerling Nile Tilapia improved growth performance.