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International Journal of Zoological Research
  Year: 2005 | Volume: 1 | Issue: 1 | Page No.: 41-47
DOI: 10.3923/ijzr.2005.41.47
Effect of Crowding Stress on Some Physiological Functions of Nile Tilapia, Oreochromis niloticus (L.) Fed Different Dietary Protein Levels
Mohsen Abdel-Tawwab, Mamdouh A. A. Mousa , Safaa M. Sharaf and Mohammad H. Ahmad

Abstract:
This study was carried out to evaluate the response of Nile tilapia, Oreochromis niloticus (L.) Fed dietary protein levels to chronic stress induced by doubling fish density. In this study, Nile tilapia (15±1 g) was randomly distributed into the aquaria at a rate of 15 or 30 fish/100 L. The temperature was adjusted at 27±1°C. Fish of each density were fed either a diet containing 25, 35 or 45% Crude Protein (CP) with a feeding rate of 3% of life body weight twice daily for two weeks. The results of this study showed that Hb and Ht were slightly reduced and no significant effect of protein level on both of them. The RBCs count in chronically stressed fish by high fish density showed such elevation and was increased significantly with increasing protein level in the diet. Glucose level in plasma was increased significantly due to high fish density especially at 25 and 35% CP. No marked changes in glucose level were observed at both fish densities at 45% CP. Protein level in the diet significantly induced plasma glucose and protein especially at low fish density. Chronic stress induced by high fish density insignificantly affected protein level in plasma. Similarly, a decrease in plasma cortisol levels due to high densities and high dietary protein levels was verified. The aspartate amninotransferase (AST) activity in liver was insignificantly reduced at high fish density and significantly increased by increasing protein level in the diet. AST activity in plasma was only significantly reduced at 45% CP, however, AST activity in fish muscle is not significantly affected by either fish density or protein level in the diet. Alanine aminotransferase (ALT) activity in plasma, liver and muscle was insignificantly affected by fish density or protein level. It could be concluded that Nile tilapia may quickly adapted to high rearing density by enhancing feed quality especially protein level in the diet to prevent the deleterious effect in fish farm.
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How to cite this article:

Mohsen Abdel-Tawwab, Mamdouh A. A. Mousa , Safaa M. Sharaf and Mohammad H. Ahmad , 2005. Effect of Crowding Stress on Some Physiological Functions of Nile Tilapia, Oreochromis niloticus (L.) Fed Different Dietary Protein Levels. International Journal of Zoological Research, 1: 41-47.

DOI: 10.3923/ijzr.2005.41.47

URL: https://scialert.net/abstract/?doi=ijzr.2005.41.47

 
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