Where W1 and W2 are the initial and final weight, respectively, and T is the number of days in the feeding period.
Feed conversion ratio (FCR) = FI (B2 + B dead – B1)-1
Where FI, B1 and B2 are the feed intake, the biomass at the start and end, respectively, and B dead is the biomass of the dead fish.
Protein efficiency ratio (PER) = (B2 – B1) PI-1
Where B1 and B2 are the biomass at the start and the end of the experiment, and PI is the protein intake.
At the end of experiment, blood samples were taken from the caudal vein of an anaesthetized fish by sterile syringe using EDTA solution used as an anticoagulant. The blood samples were used for determining erythrocyte count (Dacie and Lewis 1984) and hemoglobin content (Vankampen, 1961). Haematocrit value (Hct) were calculated according to the formulae mentioned by Britton (1963).
Plasma was obtained by centrifugation of blood at 3000 rpm for 15 min and nonhaemolyzed plasma was stored in deep freezer for further biochemical analyses. Plasma glucose was determined using glucose kits supplied by Boehring Mannheium kit, according to Trinder (1969). Total protein content was determined colorimetrically according to Henry (1964). Activities of aspartate amninotransferase (AST) and alanine aminotransferase (ALT) were determined colorimetrically according to Reitman and Frankel (1957), while lactate dehydrogenases (LDH)) were measured by using Diamond diagnostics kits according to the method of Cobaud and Warblewski (1958).
After 90 days of feeding, the fish of each group were divided into two subgroups, the first subgroup of each treatment was challenged I/P with pathogenic A. hydrophila (0.3 ml of 107 cells / ml) which was obtained from (CLAR). The second subgroup was injected i.p. by 0.3 ml of saline as control. Both subgroups kept under observation for 14 days to record the survival rate daily.
The proximate chemical analysis of fish and diets were done according to the method of AOAC (1990). Dry matter was determined after drying at 105 ºC until constant weight and ash after heating of dry samples in muffle furnace at 580ºC for 6 hours. Crude protien was determined by the Kjeldahl procedure. Total lipid was determined by extraction by petroleum eather in soxhelt apparatus.
The obtained results were analysed statistically using analysis of variance (ANOVA). Dauncan’s multiple range test (Dauncan, 1955) was used to evaluate the mean differences among different treatments at the 0.05 significant level.
In the present study, bacteriological examinations revealed that, the suspected probiotic bacterial isolates were identified as M. luteus and Psuedomonas sp. The physical and the biochemical characters of M. luteus revealed that it was Gram postive cocci, motile, oxidase and catalase were produced and oxidation/ fermintation were negative. It produced acid from arabinose, galactose and insitol. It did not produce acid