B.N. Paul

Effect of Dietary Iron Level on Growth Performance and Enzyme Activity in Rohu (Labeo rohita Hamilton) Fingerlings

The present study was intended to evaluate the effect of different levels of dietary iron (Fe) on growth performasnce of rohu, Labeo rohita, fingerlings. Six isonitrogenous purified diets were formulated using casein, gelatin and dextrin as the major ingredients. Iron was supplemented at the levels of 0, 25, 75, 100 and 125 ppm in the form of ferrous sulphate (FeSO4. 7 H2O) in groups 1, 2, 3, 4, 5 and 6, respectively for 93 days. Rohu fingerlings in group 3 showed best performance in terms of weight gain (final weight 20.66±0.23 g), specific growth rate (0.64 g/d) and feed conversion ratio (1.08). Net weight gain (NWG) was higher (P<0.01) in group 3 containing 50 ppm of inorganic Fe beyond which NWG decreased (P<0.05). The activities of aspartate transaminase, alanine transaminase and alkaline phosphatase were in the physiological range for fish. Hence, supplementation of 50 ppm Fe in the diets showed better performance in rohu fingerlings, however, further studies are required to establish optimum Fe level in this species.

Evaluation of Jute Leaf as Feed Ingredient for Labeo rohita Fingerlings

A 60 day feeding trial was conducted to evaluate the suitability of jute (Corchorus olitorius) leaf powder, as a dietary protein source for Labeo rohita fingerlings. One control feed without jute leaf JL0 (0%) and four experimental feeds were prepared with graded levels of jute leaf powder viz; JL10 (10%), JL20 (20%), JL30 (30%) and JL40 (40%) respectively along with rice bran, soybean meal, mustard oil cake, vegetable oil and vitamin-mineral mixture. The feed with 20% of jute leaves (JL20) showed significantly (P<0.05) higher net weight gain, specific growth rate, protein efficiency ratio and daily growth coefficient. The feed conversion ratio was lower (P<0.05) in JL20. The carcass composition revealed that carcass protein and lipid content was significantly (P<0.05) higher in JL20. It may be concluded that jute leaf powder can be incorporated in the feed of rohu fingerlings up to 20%.

Effect of Plant Based Feed Attractants on Growth of Cirrhinus mrigala Fingerlings

A 60-d experiment was conducted to study the efficacy of plant-based attractants in the feed of Cirrhinus mrigala fingerlings (av. weight 5.24±0.02g). The formulated feed contained mustard cake, soyabean meal, rice bran, vegetable oil, vitamin and mineral mixture with 1% feed attractants replacing rice bran. The different attractants used in feeds are: FA0 (Control), FA1 (Awbel, Cuscuta reflexa), FA2 (Kharboj, Cucumis melo), FA3 (Tambul, Zanthoxylum acanthopodium), FA4 (Chotokakla, Piper cubeba) and FA5 (Jayatri, Myristica fragrans). The net weight gain (g) was 1.05±0.15, 2.43±0.08, 1.45±0.05, 1.53±0.28, 1.50±0.02, 2.05±0.05, respectively in dietary groups Control to FA5. The growth study with different attractants revealed that the net weight gain and specific growth rate (SGR) were significantly (P 0.05) among the groups fed with different plant based feed attractants. Thus it may be concluded that out of the attractants tested in the present experiment, use of Awbel at 1% level (FA1) in the diet induced better performance in terms of growth and feed utilisation in mrigal fingerlings.