Investigation of the Role of Probiotics on Toxicity of Aflatoxin B1

Abstract

The aflatoxins are unavoidable contaminant of feed and food commodities. Among these, aflatoxin B1 (AFB) has established hepatotoxic, immuno-toxic and carcinogenic properties. AFB is grouped as class I carcinogenic by International Agency for Cancer Research (IARC). Various methods to prevent dietary exposure of AFB are: use of chemopreventive agents like Silymarin (SLM) and adsorbents e.g. mycosorb (MYC). Among adsorbents, Probiotics (Live Lactobacilli) have exhibited good AFB binding properties in vitro as well as in vivo. Traditional Pakistani yogurt (Dhai) has been reported to be good source of such Lactobacilli. The current study was designed to evaluate protective effect of these Lactobacilli (PBT) species against AFB toxicity on liver, immunity and kidneys. One day old broilers (n=240) were reared under standard environmental conditions. On 3rd week of age, the broilers were segregated into different treatment groups: I (Basal diet), II (300 g of yogurt [PBT 1X] ), III (400 ppb of AFB), IV ( 600 g of yogurt [PBT 2X]+400 ppb of AFB), V (300 g of yogurt [PBT 1X]+400 ppb of AFB), VI (SLM 600mg/Kg body weight+400 ppb of AFB), VII (MYC 1g/Kg of feed+400 ppb of AFB). The above treatments were continued for two weeks i.e. 4th & 5th week of age. All birds were vaccinated against regional prevailing diseases such as Newcastle disease, Infectious bursal disease, etc. Two ml blood was collected on 4th, 5th, 6th and 7th weeks of age for measuring leukocytes count, serum antibody titre against Newcastle Disease Virus (NDV) and clinical chemistry. Birds after weighing were euthanized and internal xvii organs such as liver, spleen, bursa of Fabricius and kidney were collected for histopathological examination and determination of AFB residue in the liver. Data thus obtained were analyzed by two way ANOVA with LSD test (α=0.05) for multiple comparison. Ingestion of AFB resulted in significant decline in total body weight and relative weight of spleen and bursa of Fabricius, serum NDV antibody titer, total serum proteins and serum albumin. Moreover, significant rise in relative weight of liver, serum GPT, bilirubin and AFB residue in the liver were recorded in AFB-treated birds (p<0.05). Histopathological examination revealed vacuolar degeneration, bile duct hyperplasia and loss of hepatic chord in the AFB-treated birds. MYC intake significantly restored the negative effects of AFB in birds by its adsorptive action during exposure (p<0.05). The SLM intake caused substantial protection against harmful effects of AFB but the effect appeared on second week of exposure (p<0.05). However, protective effects of both SLM and MYC were lost when intake was stopped. Birds receiving PBT showed better NDV-antibody titer, normalized organs weight, serum total proteins, albumin, GPT and bilirubin (p<0.05) Histopathological findings also reflected shielding effects of PBT. The protective action of PBT was observed during the exposure as well as post exposure. It is concluded that Lactobacilli (PBT) in the Pakistani food significantly ameliorate the negative effect of AFB on immune system and liver presumably via its adsorptive properties which result in declined AFB bioavailability. Furthermore, investigations are needed to elucidate mechanism of protective action of such PBT persisting even after stopping of intake of PBT.