| Aflatoxins were widespread contaminants of foods, feeds and soil ,which could result in a variable toxicosis from death to adverse effects on productivity and health of host consuming contaminated diets ,depending on their concentration . They were among the most potent hepatocarcinogens and their high toxicity to both animals and humans made them the most dangerous known mycotoxins. The most toxic aflatoxin has been designated aflatoxin B1(AFB1) and its toxic metabolite could residue in animal products. Consequently, how to alleviate the toxicity of AFB1 had become the highlight in the area of feed science . Montmorillonite was stability with chemical characteristic and had great specific surface area and high adsorption ability ,which implied a good prospect of montmorillonite utilized as mycotoxin adsorbents in feed. The objective of this study were to investigate the adsorptive properties of AFB1, lysine (Lys), methionine (Met), vitamin B2 (VitB2), on montmorillonite and modified montmorillonite, inspect the detoxify effect of montmorillonite and modified montmorillonite for AFB1 in animals , and explore the mechanism of AFB1 adsorption on them by isothemal adsorption experiment , desorption experiment, everted small intestine sack experiment, acute toxicity experiment with duckling and chronic toxicity experiment with broiler , X-ray diffraction and infrared absorption spectrum. The main results of the study were as following.1 The isothermal adsorption of AFB1 on montmorillonite and modified montmorillonite was fitted by Langmuir and Freundlich equation. The maxium amount of AFB1 adsorbed on montmorillonite was 613.5 and 628.9 礸/g at pH 2.0 and pH8.0 respectively, and that on modified montmorillonite was 598.8 and 625.0 礸/g, respectively. There was no significantly different for the the maxium adsorption between montmorillonite and modified montmorillonite, but the desorbing rate of the latter was lower than the former. This results indicated that montmorillonite could get better detoxification effect for AFB1 after modified treatment.2 The level of Lys added in formula feed was about 0.2%, and Lys of the ratio did not affect the adsorption of AFB1 on montmorillonite and modified montmorollonite.3 The infrared absorption bands at 1403cm-1 and 1355cm-1 of montmorillonite and modified montmorillonite were weaken or disappeared after AFB1 was adsorbed ,which indicated mat the chemical adsorption existed. The main chemical mechanism of the adsorption was the formation of double hydrogen bands between AFB1 and montmorillonite or modified montmorillonite.4 The adsorption reaction of AFB1 on montmorillonite and modified montmorillonite was described by the first order reaction,the half time of AFB1 disappeared ranged from 14.4 to 16.7 min in initial stage of the reaction. The adsorption reaction reached balance after 20 min.5 The bigest infrared absorption band of AFB1 in a thin KBr disk prepared under high pressure was 1749cm-1, the sequence after 1749cm-1 were 1589 cm-1,l479 cm-1,1621 cm-1, 1548 cm-1, 1126 cm-1,1425cm-1, 1066 cm-1.6 The maximum amount of Lys adsorbed on montmorillonite was 64.1mg./g and 49.3mg/g at pH2.0 and pH8.0 respectively ,and the maximum amount of lysine adsorbed on modified montmorillonite was45.4mg/g and 33.8mg/g respectively. Met was not adsorbed on montmorillonite and modified montmorillonite as the concentration of was lower than 0.2%.The isothermal adsorption of vitamin B2 on montmorillonite and modified montmorillonite was fitted by the Nernst model .Lys and VitB2 could be desorbed from adsorptive complex partially. The adsorption amount of Lys and VitB2 on montmorillonite was more than that on modified montmorillonite, but their desorbing rate from montmorillonite adsorptive complex was less than that from modified montmorilloniteadsorption complex.These results showed that the adsorptive characteristic of montmorillonite could be improved by modified treatment.7 There was a active assimilation mechanism of aflatoxin B1 in chick small... |
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