الفهرس 
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Abstract
The present study aimed to identifying the main bacterial agent causing disease
problem among P.hypophthalamus fish in semi intensive and intensive fish
farms in Egypt and to assessment the efficacy of nucleotides (Nucleoforce™)
on growth, hematological, non-specific immunological parameters and disease
resistance in pangasius hypophthalmus fish.
This study was conducted on 70 diseased Pangasius hypophthalmus fish
collected from different Pangasius fish farms in Egypt. Bacteriological
examination revealed the isolation of Pseudomonas aeruginosa that was
biochemically confirmed using MALDI-TOF MS and VITEK 2 compact
system. The prevalence and virulence of Pseudomonas aeruginosa were
estimated genotypically using species specific 16S rDNA gene, OprL and ToxA
virulent genes for detection of pathogenic strains followed by sequencing
analysis. Pathogenicity of isolated Pseudomonas aeruginosa was confirmed by
experimental intraperitoneal injection of healthy Pangasius hypophthalmus with
positively virulent strains resulting in high mortalities among injected fish.
Dietary nucleotides were incorporated in diet at different concentrations; group I
control, group II 250 g/ ton diet and group III 500 g/ ton diet for 8 weeks. At the
end of feeding trial, weight gain and specific growth rate (SGR) were recorded.
Results showed that there was a significant increase in WG, SGR in fish groups
received diet supplemented with nucleotides in comparison with the controlgroup. Haematogram indices showed a significant elevation in RBCs count, HB
value, WBCs and leukocytic count. Biochemically, High super oxide dismutase
(SOD) activity, total protein and globulin levels were recorded in fish fed on
500g/t nucleotide (NT). Immunologically, Lymphocytic proliferation activity,
Nitric oxide concentration and Serum lysozyme activity were continuously
increased in 250g/t and the 500g/t NT treatment groups along feeding duration.
In conclusion, the supplementation of fish diet with nucleotides in concentration
of 500g/t nucleotide can improve the general health status of P. hypophthalmus
via increasing the disease resistance against P. aeruginosa.