No abstract

ABSTRACThe present investigation was conducted to study the effect of dietary supplementation of the probiotics Bacillus subtilis, Lactobucillus plantarum, a mixture of both bacterial isolates (B.subtilis and L. plantarum) and the yeast, Sacchromyces cerevisiae on the immune response of the Nile tilapia, Oreochromis niloticus. Two experimental diets were conducted. In the first experiment O. niloticus ( 24.55±0.03g) were fed for 60 days on four experimental diets supplemented with B. subtilis (10 7 CFU/g ) (D1), L. plantarum (10 7 CFU/g) (D2) a mixture of B. subtilis and L. plantarum (D3) and the yeast Sacchromyces cerevisiae (D4) and a control non-supplemented diet. All of the four experimental diets showed significantly increased phagocytic activity, acid phosphatase activity, lysozyme activity and total immunoglobulin activity in blood samples of the fish as compared with the control nonsupplemented diet. In the second experiment, O. niloticus (35.05±0.01g) were fed on a diet supplemented with three concentrations of L. plantarum (10 5 , 10 7 and 10 9 CFU/g) (D1, D2 and D3) respectively for 60 days. The probiotic treatment increased significantly the phagocytic activity for fish fed D2, while acid phosphatase activity was significantly increased for fish fed D3. Diets (D2 and D3) showed significantly the highest levels of lysozyme activity. No significant differences between the three diets for phenoloxidase activity, while total immunoglobulin showed significantly increased levels for fish fed D1 and D3 respectively. The results of the present study support the use of probiotics as immunostimulants in common fish diets.

T iver specimens were taken from seventy fish of, Tilapia zillii 9 living-■-' in three different localities in Qalyobya govemorate; unpolluted, agricultural-polluted and industrial-polluted waters of the River Nile. Water analysis was carried out to evaluate the heavy metals in these tested localities. Polymorphism of liver proteins was revealed by SDS-PAGE electrophoresis. Also, DNA damage was detected by counting the fragmentation percent. Results showed that the measured heavy metals were higher in the agricultural and industrial localities than in control; and sometimes exceeded the permissible concentrations. Fractions of liver proteins showed disappearance and polymorphism in the fish especially that was very close to the outlets of agricultural and industrial drainage water. Additionally, both agricultural and industrial pollution caused an increase in the percentage of DNA fragmentation, however the impact of industrial pollution was higher than that of agricultural pollution, The study suggested that there is clear molecular changes in T. zillii; this declares the use of these molecular parameters in diagnosing pollution.

The objective of the present study was to determine the dietary iron requirement for the Nile tilapia, Oreochromis niloticus fmgerlings in intensive fish culture system. O. niloticus fmgerlings (25.36±0.11g) were stocked in fiberglass tanks (lm 3) under water running system at a density of 40 fish/m 3 with a feeding level of 3% of body weight. Six purified diets containing different iron levels (0, 200, 400, 800, 1200 &1600 mg Fe/ Kg) in a form of ferrous sulphate were tested on the Nile tilapia for 8 weeks. Results revealed that FBW and SGR were the highest (P<0,05) in the fish group fed on the diet supplemented with 1200mg Fe /Kg and the lowest were recorded in fish fed on the iron free diet. Each of K and FI were insignificantly affected by dietary iron levels. The lowest value of FCR was recorded for fish fed on 1200mg Fe/ Kg diet. The results of the present study revealed that, the group offish fed 1200-mg Fe /Kg diet had significantly(P<0.05) the highest value of average daily gain in weight PPV and ER. Red blood cell count, haemoglobin and haematocrit values were increased with increasing the level of iron and significantly affected by dietary iron levels. The highest value of MCH was recorded for fish fed 1200 mg Fe /Kg diet. The lowest values of RBCs, Hb, ,Hct s MCV r MCH and MCHC were recorded for fish fed on iron free diet. TotaL plasma proteins and plasma glucose values were not significantly affected by increasing dietary iron level, while plasma cholesterol increased significantly by increasing the level of iron in the diet. The results of the present study suggest that iron supplemented to the diet up to a level of 166 Sabry S. El-Serafy et al 1200mg Fe/ Kg diet from ferrous sulphate improves the growth performance and haematological parameters of O. niloticus fingerlings.