Optimum selenium requirement of juvenile Nile tilapia, Oreochromis niloticus

Abstract

A feeding experiment was conducted to determine the optimum selenium requirement in juvenile Nile tilapia. Each of six purified diets with Se‐methionine levels at 0.05, 0.21, 0.41, 0.57, 0.79 and 1.00 mg/kg was assayed in triplicate with initial body weight of 3.00 ± 0.01 g for 8 weeks. The growth of fish was obviously increased when the dietary Se was less than 0.57 mg/kg diet and reached a plateau when the dietary Se was ≥0.57 mg/kg. Serum and hepatopancreatic glutathione peroxidase (GPx) activity increased markedly when the dietary Se was less than 0.57 mg/kg, but then decreased when the dietary Se was higher than 0.57 mg/kg. The malondialdehyde contents in hepatopancreas were significantly decreased when the dietary Se was higher than 0.79 mg/kg. No significant differences were observed in hepatopancreatic total antioxidant capability (T‐AOC) among the groups (p > .05). The results of this study indicated that Se addition as Se‐methionine was essential, while both the deficiency and excess levels of dietary Se would cause negative effects on growth or antioxidant capability in juvenile Nile tilapia. Based on broken‐line regression of WG and piecewise regression of liver GPx, the optimum requirement of Se for juvenile Nile tilapia is 0.57 mg/kg diet.

Nutrition and Metabolism of Minerals in Fish

“…Unlike other micronutrients, gross deficiency of Se alone has not been characterized due to its interaction with vitamin E, polyunsaturated fatty acids and other dietary factors. Early clinical signs of deficiency caused by low dietary intake of Se have been detected in low enzyme activities in plasma and liver glutathione peroxidase of several fish species [ 145 , 146 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 180 , 181 ]. Selenium deficiency led to reduced growth in rainbow trout [ 146 ], carp [ 182 ] and catfish [ 170 ], but Se deprivation did not lead to any pathological signs in these species.…”

Effects of Chromium-L-Methionine in Combination with a Zinc Amino Acid Complex or Selenomethionine on Growth Performance, Intestinal Morphology, and Antioxidative Enzymes in Red Tilapia Oreochromis spp.

“…Selenium is an essential element in nutrition; it is the major component of selenoprotein, which is important for antioxidative stress mechanisms, thyroid hormone metabolism, and immune responses [ 96 ]. Ning et al [ 97 ] showed that the dietary supplementation of selenium at 570 ppb could enhance weight gain and increase hepatopancreatic and serum selenium levels in juvenile Nile tilapia, depending on glutathione peroxidase activities. Accordingly, this supplementation rate is recommended for juvenile Nile tilapia.…”