The efficacy of three mycotoxin adsorbents to alleviate aflatoxin B1-induced toxicity in Oreochromis niloticus

Khaled M Selim,Riad H Khalil,Hana El-Hofy

doi:10.1007/s10499-013-9661-6

Abstract

Aflatoxicosis, toxicity of aflatoxin, is of great concern in aquaculture. This study was conducted to assess the efficacies of three adsorbents, a hydrated sodium calcium aluminosilicates (HSCAS), Saccharomyces cerevisiae (S.C.) and an esterified glucomannan (EGM), against feed contaminated with contained 200 μg/kg (ppb) aflatoxin B1 (AFB1). A total of 240 Nile tilapia fingerlings, Oreochromis niloticus (15 ± 2 g), were randomly divided into eight experimental groups (30 fish per group) with three replicates. Group T1 represented the negative control fed on a basal diet, and T2 was the positive control group fed on a basal diet supplemented with 200 ppb AFB1. Groups T3, T4 and T5 were fed the AFB1-contaminated diet (200 ppb) supplemented with 0.5 % HSCAS, 0.25 % S.C or 0.25 % EGM, respectively. Groups T6, T7 and T8 were fed a basal diet supplemented with 0.5 % HSCAS, 0.25 % S.C or 0.25 % EGM, respectively. The reduction in AFB1-bioavailability was judged by toxin residues in fish musculature throughout the study beginning at the second week of exposure. AFB1 reduced the survivability, total weight gain, average daily gain and specific growth rate, evident as early as the second week of exposure. The total erythrocyte count, hemoglobin content and total leukocyte count were significantly decreased after AFB1 exposure for 6, 8 and 10 weeks, respectively. Prolonged administration of AFB1 led to significant increases in serum alanine transaminase, aspartate transaminase and creatinine activity, and produced significant decreases in plasma proteins, including serum globulin. The specific immune response was assessed by an agglutinating antibody titer after immunization of the fish with an Aeromonas hydrophila vaccine. The antibody titer and relative level of protection of fish challenged with Aeromonas hydrophila were reduced throughout the period of examination in AFB1-exposed fish. Supplementation with HSCAS, S.C. or EGM significantly improved growth performance, blood parameters and immune status; in addition, these groups showed decreased AFB1 residues in fish musculature when compared with AFB1-treated fish. HSCAS effectively reduced AFB1 toxicity, whereas S.C. and EGM were less efficacious.

Highlights

Aflatoxins are secondary metabolites of the fungus Aspergillus flavus, A. parasiticus and A. nominus
The groups not exposed to aflatoxin B1 (AFB1) (T1, T6, T7 and T8) showed a significant (P \ 0.05) increase in total weight gain (TWG) of over 200 %
The main clinical signs of AFB1 toxicity are chronic in nature, including impaired liver function, lower growth rate, loss of body weight, increased disease susceptibility, internal organ dysfunction and increased mortality (Murjani 2003; Santacroce et al 2008)

Summary

Introduction

Aflatoxins are secondary metabolites of the fungus Aspergillus flavus, A. parasiticus and A. nominus. Aflatoxin B1 (AFB1) is the most frequent, potent and toxic metabolite in humans, animals and aquatic organisms (Kennedy et al 1998; Hussein and Brasel 2001). Trout are the most sensitive fish to AFB1 (Horn et al 1989). Other species such as channel catfish, coho salmon and zebrafish are less sensitive (Hendricks and Bailey 1989; Plakas et al 1991; Tsai 1996). Nile tilapia is influenced by the deleterious effects of AFB1 as low as 1.5 ppm (Zychowski et al 2013). Albumin and globulin levels were significantly lower in hybrid tilapia and rohu exposed to AFB1 (Deng et al 2010; Mohapatra et al 2011). The bacterial agglutination titer and relative levels of protection were significantly suppressed due to AFB1 exposure (Sahoo and Mukherjee 2001, 2003)

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Conclusion