【作者】 卢永红；

【导师】 陈杰；

【作者基本信息】 南京农业大学 ， 预防兽医， 2006， 博士

【摘要】 霉菌对饲料的污染十分常见，由饲料传播的霉菌毒素就有可能在这些饲料中存在。饲料被霉菌污染后，主要引起两个方面的危害：一是由霉菌引起的饲料的变质；一是因霉菌产生的毒素而引起的动物中毒。饲料中的霉菌毒素还可能通过食物链而对人体产生危害。霉菌污染饲料后可使之饲用价值降低，甚至完全失去商品价值，从而带来巨大的经济损失。霉变饲料处理是饲料毒物与抗营养因子研究领域的一个热点。目前国内外对霉变饲料的处理主要有化学法（通常采用氢氧化钠、氨、次氯酸钠、氯气等对霉变饲料进行处理）、微生物降解法、酶降解法以及物理吸附等多种方法。本研究旨在研制新型的霉菌毒素脱毒剂，并开发应用进行研究。1、饲料霉菌毒素脱毒剂的吸附力测定通过两个试验测定饲料霉菌毒素脱毒剂的脱毒效果。试验一在霉变饲料中添加200ppm的脱毒剂，并应用ELISA方法测定黄曲霉毒素B1的吸附率。测定结果表明，饲料霉菌毒素脱毒剂对饲料黄曲霉毒素含量的脱毒率为95.48％。添加脱毒剂后，饲料黄曲霉毒素B1的含量显著降低（P＜0.01）。试验二在饲料中添加0ppm、100ppm、200ppm、300ppm和500ppm五个水平的脱毒剂，测定不同水平添加量对脱毒效果的影响。测定结果表明，在轻度霉变饲料中添加300ppm的脱毒剂比较理想。过多添加效果不明显，并使饲料成本增大。2、饲料霉菌脱毒剂的作用机理探讨实验采用Adamson乙二醇法和Grant法对SAL霉菌毒素脱毒剂的吸附面积和吸附机制进行探讨。结果表明：①SAL霉菌毒素脱毒剂的最大吸附表面积为872m²／g。②通过定量测定和定性分析，脱毒剂的△G为-33.2kJ／mol，△H_ads为-42.6kJ／mol。根据Stumm等（1992）和Gu等（1994）的研究结果，可根据脱毒剂的自由能变化（△G）和吸附熵变化△H_ads来判定脱毒剂的吸附类型。当△G=0时，吸附作用主要是物理吸附；△G＞0时为化学吸附。△H_ads＜20 kJ／mol时是物理吸附；△H_ads＞20 kJ／mol时为化学吸附。据此，可将SAL霉菌毒素吸附剂对霉菌毒素的吸附机理定为物理吸附脱毒（“电荷供体”型的物理吸附）。3、饲料霉菌脱毒剂电子显微观察采用电子显微镜对SAL霉菌脱毒剂的晶体结构进行观察，以了解研制的饲料霉菌毒素脱毒剂与常规物质的结构差异。实验通过不同的放大倍率观察脱毒剂晶体的结构特征，并用黄曲霉毒素B₁进行吸附情况的模拟。结果表明：①常规物质的分子结构多呈球状结构，而脱毒剂则明显呈多孔结构，孔径大小十分均匀，不受脱毒剂颗粒大小的影响。②脱毒剂的内表面积远大于外表面积，其内表面在发挥脱毒剂效力方面起决定作用。4、霉菌毒素脱毒剂对饲料维生素的影响实验采用HPLC法分别研究了申维净对OTA的吸附能力，并探讨了V_C、V_E对申维净吸附能力的干扰作用。结果表明：①申维净对OTA有很强的吸附能力，其单位质量的吸附量随OTA浓度的增大呈线性提高；②申维净对OTA的吸附不受V_C、C_E的干扰，表明申维净对霉菌毒素OTA是选择性吸附。5、饲料霉菌毒素脱毒剂对肉鸡生产性能的影响选用900羽1日龄AA健康肉鸡进行为期49日龄的试验，就饲料霉菌毒素对肉鸡生产性能的影响进行研究。试验结果表明：黄曲霉毒素B₁可显著降低肉鸡的体增重和饲料利用率；在饲料中添加霉菌毒素脱毒剂可消除黄曲霉毒素B₁对肉鸡生产性能的不良影响。6、饲料霉菌脱毒剂在养猪生产上的应用本试验旨在对饲料黄曲霉毒素B₁对仔猪生产性能的影响以及添加霉菌毒素脱毒剂后的脱毒饲喂效果进行研究。试验选用35日龄三元杂交仔猪180头，随机分为三组，其中对照组饲喂正常日粮，试验一组日粮在对照组日粮基础上添加2.5mg／kg的黄曲霉毒素B₁，三组日粮在试验一组日粮中添加200ppm的SAL霉菌解毒剂。试验结果表明：①仔猪采食添加黄曲霉毒素B₁的饲料后，采食量和生长速度显著下降，饲料转化率显著降低。其中，仔猪采食量下降是导致仔猪生长速度下降的主要因素。②通过在饲料中添加适量的霉菌毒素脱毒剂，仔猪的采食量和生长速度与对照组无显著差异，表明饲料霉菌毒素脱毒剂可基本消除霉菌毒素对猪增重和饲料转化率的不良影响，饲料转化率得到显著改善。更多还原

【Abstract】 The mold contamination of animal feed is very common because feeds can provideexisting environment for molds. The molds will produce mycotoxins, which are usuallydiffused by contaminated feeds and persist to exist in these feeds. Mold will bring twokinds of endangerment to the contaminated feed. One is feed deterioration caused by mold,and the other is animal intoxication caused by mycotoxins. Mycotoxins in animal feed mayalso bring harm to human health through food chain. Mold contamination will reduceutilization value of feed, even made the commercial value of feed lost completely. Thesevere problem of mold contamination has caused huge economy loss to feed industry.Research on moldy feed treatment is very popular nowadays, which helps combatfeed poison and anti-nourishment factors. There are several methods for detoxifying moldyfeed, among them are chemical methods （usually treating moldy feed with sodium hydrate,ammonia, sodium hypochlorite, chlorine）, microbial degradation methods, enzymedegradation methods and physical adsorption methods.This study was focused on mechanisms of detoxification of a mycotoxin antidote,which was a new product developed in the research group.1. Test of adsorbent capability of the feed mycotoxin antidoteThe experiment evaluated detoxication efficiency of the mycotoxin antidote. AFB1adsorbing capacity of antidote SAL was evaluated by ELISA.①AFB₁ adsorbing rate to SAL was 95.48%;②When concentration of SAL was between 300-500 ppm, aflatoxin B1 detoxifyingefficiency of SAL enhanced with increasing SAL concentration. When SAL concentrationwas above 500 ppm, the detoxification efficiency was no longer improved.2. Function mechanism of the feed mycotoxins antidoteThe experiment was conducted to study the adsorption area and adsorption mechanism of feed mycotoxin antidote SAL prepared with glycol or Grant method. The experimentgave the following results.①The maximum adsorption area of antidote SAL was 872 m²/g.②The A G of the antidote was -33.2 kJ/mol, the A Hads was -42.6 kJ/mol. Referring tothe research by Stumm （1992） and Gu （1994）, we could designate the types of antidote’sadsorption according to the free energy change（△G） and adsorption entropy change (△H_ads).△G=0 characterized a physical adsorption, so△G＞0 meant a chemical adsorption.△H_ads＜20kJ/mol characterized a physical adsorption while△H_ads＞20 kJ/tool reflected a chemicaladsorption. For reasons given above, the mechanism of mycotoxin adsorption to antidote isdesignated as "charge receptor" mediated physical adsorption.3. Ultra-Microstructure analysis of SALMolecular （or crystal） structures of SAL were compared with regular materials and thefollowing results were reached.①Molecular structure of SAL was porous while the regular material was usuallyspheroid and solid. The pore size was uniform, regardless of the size of SAL.②Area of inside surface of SAL was much bigger than the outer surface area, so insidesurface was efficiency deciding in detoxification.③According to chemical composition, detoxification function of SAL depended on"the electron accepter adsorption mechanism"4. The effect of Shenweijig on the vitaminsAbsorptive capacity of Shenweijing to OTA was measured with HPLC. Effect of Vc and Ve onabsorptive ability of Shenweijing to OTA was also analyzed. The study showed that Shenweijing owns aconsiderable capacity of absorption to OTA, the amount of which to be absorbed has a positivelinearized relationship with OTA concentration. The study also showed that the absorptive capacity ofShenweijing to OTA was not influenced by Vc or Ve. The absorption of Shenweijing to OTA is selective in nature.5. Application to broiler production900 AA broilers of 1 day old were selected to determine the effect of SAL onproduction efficiency.①Aflatoxin B1 could reduce the growth rate and feed conversion rate of broilerssignificantly. Adding SAL to feed could alleviate negative effects of aflatxion on weightgain and feed transform rate.②The amount of aflatoxin B1 in broiler liver would increase when the amount or timeof aflatoxin B1 in feed increased. Adding SAL into the feed could reduce the accumulationof aflatoxin B1 in the liver but could not make a complete clearance.6. Application to pig production180 hybrid pigs of 30 day old were selected to determine the effect of SAL on pigproduction. The following were main results.①Aflatoxin could significantly reduce food intake and growth rate of the animals.Aflatoxin could also reduce feed conversion rate.②SAL in pig feed could alleviate or remove the negative effects of mycotoxins on dailygain and feed conversion rate. It was also found that SAL could improve the weight gainand feed conversion efficiency significantly.更多还原