Impact of low water temperature on natural immunity of Oreochromis niloticus with special reference to haematological and pathological responses
Abstract: The impact of sharp water temperature drop from 25 ± 1C to 10 ± 1 C on natural O.niloticus serum killing activity as well as the consequent haematological , histological and experimental challenge responses were studied . The natural killing activity of O.niloticus fresh serum taken from temperature stressed fish was almost stopped in comparison to the optimum activity in non-stressed fish continuously kept at 25 ± 1C . Haematlogical responses were represented by significant decrease in total leukocytic and lymphocytes counts 70 h post temperature drop . Although non of the temperature stressed fish died , they displayed histological nephrotic changes in the form of cloudy swelling and hyaline droplet degeneration of the renal tubular epithelia 48 h post temperature drop . Challenging trials with Aeromonas hydrophila strains as an estimate of natural immune status and disease resistance of fish groups at 10 ± 1C and 25 ± 1C proved that temperature stressed fishes got infected after challenge . In comparison , fish groups kept at 25 ± 1C developed resistance to the acquisition of infection post challenge . The relative association of virulence profiles of A.hydrophila strains with the serum killing activity and the pathology of challenged fish is also discussed .

Publication year 2003
Organization Name
Country Egypt
serial title مجلة الباثولوجيا المقارنة والباثولوجيا الاكلينيكية
Department Fish Diseases
Author(s) from ARC
Agris Categories Animal diseases
AGROVOC
TERMS		 Immunity. Oreochromis niloticus.
Proposed Agrovoc low water temperature ;
Publication Type Journal
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