Enzymatic alterations in Litopenaeus vannamei (Boone,1931) juveniles exposed to different levels of dietary potassium and magnesium reared in inland saline water.

Abstract

Inland saline water (ISW) are deficient in potassium with high levels of calcium and variable concentrations of magnesium, large steps were taken to balance these essential ions using commercial fertilizers for growth of Litopenaeus vannamei. Since these methods needs large quantities of fertilizers and involves high cost, the present study was made to explore the use desired mineral supplements through feed rather than in water. A 60 days trial was conducted to investigate the effect of different dietary levels of K+ , Mg2+ on L. vannamei juveniles in two types of water namely raw (R-ISW) and 100% K+ - Mg2+ fortified water (F-ISW) as sea water at constant salinity 10 ppt. Three gelatin coated diet were formulated with varied K+ and Mg2+ levels (K+ = 5 g/kg, Mg 2+ = 150 mg/kg, K+ = 10 g/kg, Mg2+= 300 mg/kg, K+ = 15g/kg, Mg2+ = 450 mg/kg) and commercial shrimp feed serves as basal diet. There is a significant difference in enzymatic activity in all treatments regarding with or without supplemented feed in F-ISW and R-ISW. Enzymatic activity of hemolymph parameters, SOD, Catalase, AST, ALT and total haemocyte counts were significant different (P<0.05) in both F-ISW with dietary minerals ions alteration and in FISW without supplemented feed as compared to other treatments. There was a significant (P<0.05) higher difference in digestive enzymes in F-ISW compared to other treatments. The present study indicates that there is stress for treatments where lack of dietary mineral ions in ISW compared to F-ISW.