Dietary phosphorus requirement and deficiency sydromes in macrobrachium rosenbergii juveniles
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Date
1996
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Department of Aquaculture, College of Fisheries, Panangad
Abstract
The objective of the present study is to find out the optimum dietary requirement and to characterise the symptoms of the dietary deficiency and excess of phosphorus in Macrobrachiumrosenbergii juveniles.
The prawns were fed with casein – based semipurified diet containing graded levels of supplemental phosphorus in the form of sodium dihydrogen phosphate (NaH2 PO4. 2H2O) under defined environmental conditions for a period of 84 days.
The survival and growth of the prawn was not significantly influenced by the varying dietary phosphorus supplementation. The maximum specific growth rate of 1.9 + 0.13% was obtained in prawns fed with diet containing 1.76% phosphorus and with a Ca:P ratio of 1:1.68. Phosphorus level in the diet and the Ca: P ratio showed significant influence on the food conversion efficiency, protein efficiency ratio, wholebody phosphorus and wholebody calcium content of the prawn. The wholebody calcium increases with phosphorus level of the diet. Non – linear regression estimate based on the phosphorus mineralization of wholebody tissue of prawn indicates an optimum requirement of 1.7861% of phosphorus in the diet. The prawns maintain the body Ca: P ratio of 1:1 at or near the optimum dietary phosphorus level. Very low levels of phosphorus in the diet produced deficiency symptoms such as lack of pigmentation general body opaqueness, stunted growth, reduced protein efficiency and low wholebody phosphorus, calcium and Ca:P ratio. Symptoms of excess level of dietary phosphorus were general body opaqueness, stunted growth, whitish patches on the body, white spots on the walking legs, black melanised lesions on the abdomen, reduced protein efficiency and abnormal increase wholebody phosphorus and calcium with a lowering of Ca:P ratio.
This study shows the optimum requirement of 1.8% dietary phosphorus for the giant fresh water prawn, the deficiency and excess of which leads to adverse effects.
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Citation
170711