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Effect of probiotics on the survival, growth and challenge infection in Tilapia nilotica ( Oreochromis niloticus )
Author(s) -
Aly Salah Mesalhy,
Mohamed Mohamed Fathi,
John George
Publication year - 2008
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.2008.01932.x
Subject(s) - biology , tilapia , oreochromis , aeromonas hydrophila , bacillus pumilus , zoology , body weight , nile tilapia , veterinary medicine , fish <actinopterygii> , bacteria , fishery , endocrinology , medicine , genetics
This study was conducted in order to evaluate the potential benefit of Bacillus pumilus and a commercial product (‘Organic Green' ™ ) as a probiotic in the culture of the tilapia nilotica . Two doses of B. pumilus (10 6 and 10 12 g −1 diet fed) and Organic Green ™ (1 and 2 g kg −1 diet fed) were used as feed additives and administered for periods of 1 (groups 2, 3, 4 and 5 respectively) and 2 (groups 6, 7, 8 and 9 respectively) months; group 1 served as a control. Each group consisted of 4 equal replicates of 320 fish. Body weight, nitroblue tetrazolium (NBT) activity, haematocrit values and total and differential leucocytic counts (TLC and DLC) were recorded in each group after 1 and 2 months. At the end of the experiment (8 months), survival and individual body weights were recorded. Challenge infections were performed after 1, 2 and 8 months using 0.5 mL culture suspension of a pathogenic reference strain of Aeromonas hydrophila (10 8 bacteria mL −1 ). The NBT values were increased significantly in all treated groups, except those administered B. pumillus (groups 3 and 6). There were significant changes in haematocrit values and TLC and DLCs in the treated groups, except group 3, which showed a significant increase in TLC, lymphocytes and monocytes. There was a statistically significant increase in the individual body weight in groups 5, 6, 8 and 9. The survival rates of all treatment groups were higher than the control group, the differences being statistically significant in groups 3 and 9. The challenge infection showed a variable response with the type and dose of treatment and the period of application. The highest relative levels of protection were an average increase of 62.5% after 1 month (groups 3 and 5), 55.6% after 2 months (group 7) and 15.8% after 8 months (groups 8 and 9). Overall, both types of probiotics induced a similar effect. The results show the potential of using probiotics to enhance immune and health status and improve disease resistance in Oreochromis niloticus , thereby improving growth performance. However, further extensive testing, including a full commercial cost–benefit analysis, is necessary before recommending their application in aquaculture.