Publications in the Year: 2007

Journal Article

Mahmoud AM, Abeer AERH, Nashwa A-AA.  2007.   Effect Of Confinement Stress On Behaviour, Performance, Clinicopathological And Histopathological Alterations Of Nile Tilapia Challenged With Aeromonas hydrophila With Regard To The Blue Light As Stress Inhibitor . Veterinary Medical Journal. , 55, no.3 :687-717. Abstract

The present study was carried out to assess the effects of blue light as antistressor and its effect on susceptibility of Nile tilapia (Oreochromis niloticus) to Aeromonas hydrophila (A. hydrophila) infection. A total number of (120) O. niloticus was divided into 3 experimental groups (40 fish / group). Group 1 (G1), was exposed to normal day light and considered as control group. Group 2 (G2), was exposed to blue light. Group 3 (G3), was exposed to white light (fluorescent illumination). After 15 days of light exposure, fish in groups 2 and 3 were confined into small area and then challenged with A. hydrophila infection. The obtained data revealed that during exposure to blue light, the fish of (G2) recorded significant lower proportion in behavioural parameters including factors of fright behaviour "creeping, oblique plan position and air-gulping" than those of﴾G3﴿. On the other hand, (G2) showed lower behaviour alterations for fright behaviour during confinement and infection than those of﴾G3﴿. Contrarily, it also had significantly higher proportions of aggressive behaviour during exposure to light, confinement and infection than﴾ G3﴿. SO blue light improved behaviour and fish become more comfortable in (G2) than (G3). Moreover, fish of (G2) showed higher significant growth performance during exposure to blue light and little reduction in growth performance during exposure to both confinement and infection than those of (G3). The clinicopathological studies revealed significant increase in the stress response indicators after exposure to confinement stress in (G.3). Marked elevation in the serum cortisol, glucose levels and significant leukocytosis associated with heterophilia and lymphopenia was observed in group 3 (G3). On the other hand, non significant changes were observed in the measured stress parameters in group (G 2) which exposed to the blue light. Exposure of stressed fish to A. hydrophila infection induced significant leukocytosis with heterophilia, monocytosis and lymphopenia in both (G2&G3). Analysis of serum biochemical constituents showed significant elevation in ALT, AST, BUN, creatinine and glucose while significant reduction in the total proteins, albumen and globulin was achieved. These changes were more pronounced and early detected in A. hydrophila infected stressed fish exposed to white light compared to those exposed to blue light From pathological point of view, fish group which exposed to blue light and infection revealed early positive immune response "activation of melanomacrophage center of spleen" but with time dependent adverse pathological lesion. The lesions were noticed in spleen and gills after 2 weeks. Regeneration of the most observed lesions were detected after 4 weeks. On the other hand, the fish group exposed to white light and infection showed more advanced lesions including diffuse necrosis in hepatic tissue with additional changes in the kidneys. So, the blue light has a protective effect aganist stress in Nile tilapia.

Khalil W-KB, Mahmoud MA, Zahran MM, Mahrous KF.  2007.  A sub-acute study of metronidazole toxicity assessed in Egyptian Tilapia zillii.. Journal of applied toxicology . 27:380-390. Abstract

Metronidazole (MTZ), an antiparasitic and antibacterial compound, is one of the world’s most widely used drugs. Despite being considered as a rodent mutagen and a carcinogen, it is still widely used in humans for the treatment of infections with anaerobic organisms. Therefore, the main objective of the current study was to evaluate the in vivo toxicity of MTZ using the micronucleus (MN) assay and random amplified polymorphism DNA (RAPD-PCR) analysis as well as histopathological examination in Tilapia zillii. Moreover, the protective effect of vitamin C (VitC) against toxicity of MTZ was investigated in the present study. Fish were treated with three doses of MTZ (5, 10 and 20 mg/ l) alone or in combination with VitC (200 mg/ kg food) at several time intervals (2 days, 7 days and 14 days). The results of the present study showed a significant effect of MTZ on micronucleus formation and changes in polymorphic band patterns as well as induction of different histopathological alterations in Tilapia zillii. The effects of the drug were reduced when fish were exposed to a combination of MTZ and VitC.

abd elaziz M, Ali M, yassin S, raafat and rashad AS.  2007.  Study on the effects of some probiotics on the performance, clinicopathological and histopathological changes of Oreochromis niloticus. Veterinary Medical Journal. 55, no.3 :879-897. Abstract

The presen study was carried out to evaluate the use of some probiotics on the growth rate of tilapia fishes and to determine its effect on some hematological and histopathological parameters. Two different commercial probiotics which includes biogen and moreyeast were evaluated for 8weeks. In the experiment, fifty Oreochromis niloticus fishes were classified to 3 groups,Group (1): consisted of 20 fishes which fed diet supplemented by biogen at a dose of 2 kg/ton diet. Group (2): consisted of 20 fishes which fed diet supplemented by moreyeast at a dose of 5 kg/ton diet and Group (3): was control group which consisted of 10 fishes fed diet without probiotics. At the end of the experimental period both biogen and moreyeast administrated groups revealed a significant increase in the body weight gain (W.G.). The results showed significant increase in the values of RBCs, PCV and Hb throughout the experimental period except group 1 (received biogen) at the 6th week of experiment comparing to control group. Fish group received moreyeast (Group 2) had the pronounced effect than group 1. Assessment of leukogram revealed significant leukocytosis allover the experimental period in different groups except during the 2nd week in group 2 (received moreyeast) and at the 6th week in both probiotic administrated groups comparing to control group. Fish group received biogen had pronounced effect comparing to moreyeast administrated group. differential leukocytic picture was recorded. Histopathological examination revealed The biogen and moreyeast administerd groups showed marked activation of the melano-macrophage centers which is a component of reticuloendothelial system and hence part of the defensive system of fish indicating immunoenhancment. the study concluded that: The examined probiotic were safe for the Oreochromis niloticus fish.
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