Growth performance, feed utilization and blood components of Nile Tilapia ( Oreochromis Niloticus) as affected by dietary energy levels and zinc supplementation [electronic resource].

Includes references.

The study was conducted at the Department of Animal Production, Agriculture Faculty, Zagazig University and the practical work was carried out at Central Laboratory for Aquaculture Research, Abbassa, Sharkia, Egypt. The experiment was carried from August to November, 2012. Fish were divided into twelve groups, each group was stocked into 3 aquaria and each one contains 10 fish. The fish of the first four groups were fed the diet containing 4113 Kcal/kg diet (normal energy level), the second four groups were fed the diet containing 4337 Kcallkg diet (medium energy level) and the other four groups were fed on the diet containing 4559 Kcal/kg diet (high energy level). Within each dietary energy level, fish groups were fed diets supplemented with vitamin zinc to supply 0, 25, 50 and 75 mg/kg diet. The non significant differences between the experimental groups for initial live body weight indicated that the groups at the beginning of the experiment were homogenous. Live body weight, daily gain, relative growth rate and feed conversion of Nile tilapia fish was affected insignificantly with dietary energy level. Daily weight gain of fish increased in fish fed high and medium energy levels by 5.69 and 0.19%, respectively. The energy levels on fish diets did not affected the mortality rate. Serum total protein, albumin, globulin, urea-N, creatinine, AL T and alkaline phosphatase insignificantly affected with dietary energy level, while AST and total lipids affected significantly (P<O.OO 1 or 0.01 ). Moisture, crude protein and ether extract content of the fish flesh increased with increasing dietary energy level. Final live body weight increased by 7.19, 9.20 and 13.23%, respectively in fish fed diets supplemented with 25, 50 and 75 mg zinc/kg diet, when compared with fish fed diet without zinc supplementation. The same figures for daily weight gain were 9.65, 12.28 and 17.54 %, respectively. Also, feed conversion at 0-14 weeks of the experimental period improved by 3.62, 8.72 and 8.95%, respectively. Fish groups fed diet supplemented with 75 mg zinc/kg diet recorded higher growth rate and the best feed conversion. Serum total protein, albumin, globulin, serum creatinine, alkaline phosphates and lipids significantly (P<0.001 or 0.05) affected with.

Summary in Arabic.

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