Tilapia (Oreochromis niloticus) farming effluents contain high level of ammonia, which poses a significant threat to fish and the surrounding environment. Yucca schidigera extract (YE) has been found to reduce ammonia pollution resulting from fish farming. On the other hand, dietary supplementation of Bacillus subtilis was found to improve anti-oxidation activity, and water ammonia level for fish. Therefore, the aim of the present study was to assess an inclusion of Yucca schidigera extract and Bacillus subtilis separately or in combination on anti-oxidation activity and ammonia reduction in the effluent of Nile tilapia fingerlings.
Fish were divided into 4 groups and fed for 60 days with four experimental diets which supplemented with 0.2 gkg-1diet of YE and 2 g kg-1diet of Bacillus subtilis (B) separately or in combination (YEB) and the control diet was left without addition (CON).
Results revealed the positive role of YE and B on total ammonia nitrogen (TAN) reduction (Table 1); however combination of both YE and B had less efficiency. The addition of YE or B in tilapia diets reduced TAN removing by 50% compared with the control. Superoxide dismutase (SOD) showed the best activity in YEB treatment followed by YE and B treatments while the lowest activity was recorded in the control group. Fig. 1 illustrates the effect of YE and B on anti-oxidative activity of Nile tilapia. The highest activity of Malondialdehyde (MDA) was reported in the control group while the lowest value was found in YEB group followed by YE and then B group. Glutathione peroxidase (GPx) and total antioxidant capacity (TAC) showed the highest activity in YEB followed by B treatment, while the lowest activity was recorded in YE and CON. It could be concluded that Yucca extract and bacillus can efficiently reduce ammonia in Nile tilapia effluent and boost their antioxidative activity.