tendency to develop hypochromic, microcytic anaemia.
M. luteus had a good effect on erthrocytes count, heamoglobin content and haematocrit value was increasing than control group. These results agree with Irianto and Austin (2002), who recorded an increase in erthrocyte count in fish fed on probiotic bacteria than control group. The production of immunoglobulin A (IgA) is also stimulated and protecting the mice against Salmonella typhimurium (Perdigon et al., 1990). Nikoskelainen et al. (2003) reported that the selected probiotic bacteria may have an impact on the spasific and innate immunity of fish. They recorded that (Ig) level was significantly increased with the probiotic feed group.
The plsma glucose concentration was significantly increased in fish fed with diet containing Psuedomonas sp and mixture of M. luteus and Psuedomonas sp. These the results are in agreement with those of Peters et al (1988) who found elevated of glucose levels in plasma of Salmo gairdneri when injected with Aermonas hydrophila or add to water of aquarium. The present study indicated that Psuedomonas sp may cause stress of fish. On the other hand, the plasma total proteins showed decreased significance in fish fed with diet containing Psuedomonas sp and mixture of M. luteus and Psuedomonas sp. These results agree with those of Cruz et al. (1989) who found lower total protein in plasma of Salmo gairdneri when injected with Vibrio anguillarum extracellular products intramuscularly. The present study indicated that the AST, ALT and LDH activities in plasma of O niloticus was significantly decreased in fish fed with diets containing Psuedomonas sp. and mixture of M. luteus and Psuedomonas sp. The present results agree with Palikova et al (2004) who indicated decrease of enzyme activities (AST, ALT and LDH ) in Cyprinus carpio after exposure to extract of Cyanobacteria. The decrease of these parameter may be due the severe damage of some organs liver, spleen, muscle and kidney (Cruz et al .,1989).
At the same time, results of the present investigation proved that Psuedomonas sp exhibited contrary results in the same studied parameters and hence can not be considered as O. niloticus culture. However, a mixture of both bacterial species improved the protein content of fish.
In conclusion, Micrococcus luteus isolate was clearly beneficial for cultured O. niloticus when administered as a food additive. It is argued that such probiotic has a role in disease control strategies, growth promotion and it improves the blood picture and biochemical parameters among O. niloticus in aquaculture.
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