Field Study on the Mycotoxin Binding Effects of Clay in Oreochromis niloticus Feeds and Their Impacts on the Health Status throughout the Culture Season

Total aflatoxin and ochratoxin were detected in 3 naturally contaminated fish feed samples using immune-affinity method. The results revealed that the average levels of aflatoxins in the 3 examined samples were (15, 22 and 12 μg / kg) respectively while the average levels of ochratoxins were (15, 6 and 6μg / kg).The levels of aflatoxins and ochratoxins after adding different doses of clay as a mycotoxin binder, revealed that the levels of aflatoxin in the treated samples after using clay at dose 2kg / ton detected as (2,1 and zero) respectively and levels of ochratoxins were 12, 2 and 2 respectively. The levels of aflatoxins in the treated samples after using clay at a dose 4kg / ton was (1, zero and zero) respectively, while the levels of ochratoxins were 1, zero and zero respectively. The results of determination of the effects of clay on the health status and performance of Oreochromis niloticus in comparing with a control group revealed that the survival rate in control group was 81% after the end of the culture season. The results also revealed that the survival rate in group 2 which received clay treated feed was 86%. The results of regular parasitological examination revealed the identification of trichodina as external protozoa in Oreochromis niloticus from both ponds but without manifestation of disease signs. The results of bacteriological examination revealed the identification of pseudomonas flouresence from some moribund Oreochromis niloticus.