Publication date: 15 January 2020
Source: Aquaculture, Volume 515
Author(s): Eman Zahran, Engy Risha, Mohamed Hamed, Tarek Ibrahim, Dušan PalićAbstract
Consumption of feed ingredients with a naturally low level of total aflatoxins contamination and possible consequences on fish health and seafood quality is a growing concern. To investigate effects of such dietary exposure on fish health parameters, Nile tilapia (Oreochromis niloticus) were fed basal diet (control), and diet naturally contaminated with a mix of aflatoxins (AFs; AFB1and 2, AFG1 and 2) at level of 16 μg/kg (AFs group). To investigate safety and efficacy of surface-modified clinoptilolite adsorber as part of both polar and non-polar mycotoxin control and prevention strategies, we supplemented control and aflatoxin contaminated diets with Minazel-plus® at level of 2 g/kg (MZ, AFsMZ, respectively) during 8 weeks. Effects of AFs and the protective role of Minazel-plus® on fish health were evaluated using growth performance and hepatosomatic index (HSI), hematological parameters, innate immune and antioxidant responses, bioaccumulation of mycotoxins in liver and musculature, and histopathological assessment of liver and kidney tissues. Significant differences in production and health parameters were observed between AF vs. Control, and MZ supplemented groups, including a decrease of red blood cells/RBCs, hemoglobin/Hb, and blood packed cell volume (PCV), changes in dynamics of leukocyte counts (specifically neutrophils), and decrease in serum lysozyme and bactericidal activity. Further, the increase in malondialdehyde (MDA), and decrease in catalase (CAT), reduced glutathione (GSH) and superoxide dismutase (SOD) activity were observed in AFs group compared to other groups. Aflatoxin residues were detected in both liver and musculature at 1.292 and 0.263 μg/kg, respectively. Supplementation of Minazel-plus® decreased AFs residues to 0.9 (liver) and 0.022 (muscle) μg/kg. Histopathology showed marked changes in liver and kidney of fish from AFs group. Reported results strongly suggest that feed-mill monitoring strategies for aflatoxin levels in feed ingredients need to be implemented and strictly enforced especially due to possible illegal use of highly contaminated feed, as well as inadequate or missing regulations of the safety level of aflatoxins in fish feed.