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Subject: Aquaculture × End date: 1996 × Start date: 1996 × Type: Thesis ×
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    ThesisItemOpen Access
    Effect of different dietary levels of lecithin on growth,survival,moulting and body phospholipid levels in Macrobachium Rosenbergii postlarvae
    (Department of Aquaculture, College of Fisheries, Panangad, 1996) Mahesh, S; KAU; Sebastian, M J
    The effect of dietary levels of lecithin on growth, survival moulting, FCR and body phospholipid levels of early postlarval freshwater prawn macrobrachium rosen bergii was examined using semi-purified diets in a 56 day feeding experiment. Five casein-egg albumin based semi-purified diets incorporated with 0,2.5,5,7.5 and 10% of purified soy lecithin (60% phosphatidylcholine) were formulated and fed to prawns (ten numbers per treatment) with an initial mean weight of 0.05386g. In order to examine the influence of lecithin at different growth stages of postlarvae the assessment was made every fourteen days during the study period. The result showed that although the overall growth performance was not affected by dietary inclusion of lecithin, SGR% of the prawns fed with the diet containing 2.5% of lecithin showed a significant difference at P<0.01level during the first fourteen days of growth. Similarly the FCR also showed significant variation (P<0.01) between the diets tested in the first and second fortnights (14th and 28th day). In the first fortnight the diets (D1, D2 and D3) produced consistent FCR, while the diets supplemented with higher levels produced higher values. No significant differences (P<0.01) between treatments were detected with regard to survival rate, moulting frequency and body phospholipid levels of the prawns with the termination of the experiment. The prawns moulted once in every night days and no abnormalitied like exuvia entrapment were noticed in any of the experiment animals . Increment of body phospholipids with respect to levels of dietary lecithin suggests a possible replacement of body PL pool with that of dietary PL. The result of the study suggests that supplementation of lecithin at a level of 2.5% in the diet can accelerate growth and improve FCR during the early postlarval phase of Macrobrachium rosenbergii (ie, upto 4 weeks after larval settlement) beyond this, supplementation of lecithin is not needed in the diet. No other deficiency of excess symptoms was detected in the experimental prawns and it is found that lecithin is not responsible for Exuvia Entrapment Disease in Macrobrachium rosenbergii postlarvae.
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    ThesisItemOpen Access
    Dietary phosphorus requirement and deficiency sydromes in macrobrachium rosenbergii juveniles
    (Department of Aquaculture, College of Fisheries, Panangad, 1996) Saju, M S; KAU; Sebastian, M J
    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.