The Effect of Dietary Lipid Levels on the Nutrition and Growth of Juveniles of Macrobmchium rosenbergii (de Man)

Abstract

The effect of dietary lipid levels on the nutrition and biochemical composition of the giant freshwater prawn Macrobrachimn rosenbergii (de Man) was studied by incorporating graded levels of cod liver oil in semi-purified diets to provide 2,4,6,8,10,12, and 15 % lipid level. A diet devoid of lipid content was used as control diet. Prawns with 63±10 mg initial body weight were used for the study. Maximum weight gain, better feed conversion and higher protein efficiency ratio were recorded in M. rosenbergii juveniles fed with diet containing 6 and 8% dietary lipid level. After 42 days, significantly higher (p< 0.05) weight gain was recorded in 4 to 10% dietary levels of lipid than control and 2% lipid diet. However, there exist no statistically significant difference in weight gain, specific growth rate, FCR and protein efficiency ratio among 4 to 10% dietary treatments. The broken line model suggests a requirement of 4.4% lipid level in the diets of M. rosenbergii juveniles. Moreover, the results of the present study bring out the negative impact of the over supplementation of lipid (12 and 15%) in the diets of M. rosenbergii. The dietary lipid did not affect the survival of prawns and it ranged from 66.11 to 91.11%, however, an addition of 4% dietary lipid increased the survival of prawn to 82.22%. The RNA, DNA and nucleic acid ratios of the muscle tissue of prawns fed with 6 and 8% dietary lipid level were significantly (p< 0.05) higher than that of control diet, 2 and 4% dietary lipid levels. A positive correlation was recorded between the dietary and carcass lipid level, however an inverse relationship was noticed between carcass lipid and moisture content. The results of study revealed that dietary lipid had an important role on the nutrition and biochemical composition of juveniles of M.rosenbergii.