Effect of density on growth hormone and some physiological parameters and its relation to growth performance

Abstract

The experiment was performed in the central laboratory for aquaculture research, Egypt. Experimental fish about 10.2 g Nile tilapia were divided into four different treatments in different ratios, and fed on 25% protein pellets for 120 days at 3% of body weight. Some parameters like some digestive enzymes (amylase and lipase), glucose, cortisol, insulin, growth hormone, iron and total binding iron capacity were measured in blood serum; the 4th treatment showed the minimum value for theses measurements except for glucose and cortisol 153.6±9.2 mg/dl and 176.3±5.2 ng/ml, respectively. Haemoglobin showed the highest and minimum value (7.63±0.03 g/dl & 6.27±0.03 g/dl) in treatments (1 and 4) respectively. Erythrocytes count showed the highest value 2.52±0.01(X106/Cmm) in the first treatment, while the lowest value 2.09±0.03 (X106/Cmm) was recorded among treatment (4). Water samples for physico-chemical analysis were monitored bi-weekly during the study period then collected and tabulated in one mean. The growth performance of experimental fishes was significantly decreased with increasing fish density.