【作者】 史莹华；

【导师】 许梓荣；

【作者基本信息】 浙江大学 ， 动物营养与饲料科学， 2005， 博士

【摘要】 本课题应用纳米技术构建了专性高效吸附黄曲霉毒素的纳米级硅酸盐结构微粒（NSP）,通过体外和体内试验两个方面研究了NSP对黄曲霉毒素（AF）的吸附,并比较了NSP和普通硅酸盐（SP）的吸附效果,进而探讨了NSP的吸附机理。 体外试验:从吸附时间、吸附剂用量、介质pH、吸附温度等方面研究了NSP对黄曲霉毒素B₁、B₂、G₁、G₂的吸附效果,并比较了硅酸盐材料改性前后对黄曲霉毒素吸附性能的变化。试验结果表明:NSP对黄曲霉毒素具有很强的吸附作用,属于化学吸附;吸附速度快,60min可以达到吸附平衡;且解吸率低,B₁、B₂、G₁、G₂的解吸率分别为6.75%、8.21%、7.18%、9.03%,均低于10%。对吸附性能的比较结果显示:NSP对黄曲霉毒素的吸附行为符合Freundlich等温式,其吸附是多分子层的;而SP对黄曲霉毒素的吸附行为符合Langmuir等温式,其吸附是单分子层的;NSP和SP对黄曲霉毒素的吸附均为热力学自发过程;在吸附容量和吸附速率上,NSP均明显高于SP。 饲养试验:选用144头体重29.8±1.3 kg的“杜长大”三元杂交猪,随机分为6个处理组,分别饲喂如下的试验日粮:基础日粮（不含AF）、基础日粮+0.3%SP、基础日粮+0.3%NSP、基础日粮+0.1 mg/kg AF、基础日粮+0.1 mg/kg AF+0.3%SP、基础日粮+0.1 mg/kgAF+0.3%NSP。每组设3个重复,每个重复8头猪,公母各半。试验预饲期为7天,正式试验期为90天。试验猪饲喂粉料,自由采食和饮水。饲养试验结束后,按体重相近的要求,从每个处理组中各选8头（公母各半）,共48头,按常规方法屠宰。取相关组织样品进行残留量、抗氧化指标、免疫学指标、血液学指标、血清生化指标及酶活性指标等的测定。结果表明: （1）在基础日粮中添加0.1 mg/kg的黄曲霉毒素,严重影响了试验猪的生长发育,显著降低了试验猪的日增重和饲料转化效率,抑制了机体的抗氧化能力、免疫功能和造血功能,严重损害了试验猪的肝脏和肾脏功能,造成了相关指标的异常升高或降低。 （2）在基础日粮中添加NSP和SP对试验猪的生长性能及其它各项指标均无明显影响,提示硅酸盐材料本身对动物是无毒无害的,可以安全地添加于饲料中。 （3）在黄曲霉毒素污染的日粮（0.1 mg/kg AF）中,添加0.3%的NSP,可以极更多还原

【Abstract】 In the present work, a novel high affinity sorbent for aflatoxin （NSP） was constructed by nano-technology. The objective of this study was to evaluate the ability of NSP to adsorb aflatoxin （AF） in vitro and the efficacy of NSP to protect against aflatoxicosis of pigs and to reduce aflatoxin residues in body tissues （in vivo）.The influence of shaking time, NSP amount, solution pH and equilibrium temperature on the adsorption of NSP for aflatoxin was studied and the influence of modification on adsorption was also evaluated. The results showed that the adsorption of NSP for aflatoxin was strong and quick, the adsorption reached equilibrium after 60 min, the desorption rate of aflatoxin from NSP was low and less than 10% （the desorption rate of B₁, B₂, G₁ and G₂ were 6.75%, 8.21%, 7.18%, 9.03% respectively）, which was a chemisorption process. The adsorption of NSP for aflatoxin occured in polylayers, the data was fitted to Freundlich equation; the adsorption of SP for aflatoxin occured in monolayer, the data was fitted to Langmuir equation. Both the adsorption process were spontaneous in thermodynamics, but the adsorption ability of NSP was significantly better than SP in adsorption affinity, capacity and rate, via nano-modification.A total of 144 crossbred （Duroc×Landrace×Large white） weaned barrows and gilts （mean body weight, 29.8±1.3 kg） were identified by individual ear tags and tattoos, and randomly assigned to six treatment groups by sex （three replicates per treatment with eight pigs per replicate）, housed in concrete-floored indoor pens, and provided with corn/soybean diets and water ad libitum. The diets either met or exceeded critical nutrient concentrations, as recommended by the National Research Council （1998）. Six dietary treatments of control feed without addition of NSP and AF, 0.3% SP, 0.3% NSP, 0.1 mg/kg AF, 0.1 mg/kg AF plus 0.3% SP, 0.1 mg/kg AF plus 0.3% NSP were fed to treatment groups for 90 days.Body weight and feed consumption were recorded to calculate average daily gain （ADG）, average daily feed intake （ADFI） and feed/gain （F/G） for each replicate. Upon termination of the feeding trial, 8 randomly selected pigs （4 barrows and 4 gilts） fromeach treatment were slaughtered after a 24h fast. Blood samples were taken via jugular venipuncture and related tissue samples were collected for analysis. After determination of all samples and statistical analysis of the data, main results were obtained as follows:（1） AF can significantly affect overall pig health and growth performance, decrease BW gain and feed conversion ratio, reduce antioxidant ability and immune competence, injure hepatic and renal function, then cause significant alterations of related parameters.（2） No significant differences in pig growth performance and other related parameters were found between the control pigs, the pigs fed NSP alone and the pigs fed SP alone, indicating that the silicate material was inert and nontoxic and can be added in diet safely as a feed additive.（3） The addition of 0.3% NSP to AF-contaminated diet can significantly reduce aflatoxin residues in pig tissues to a very low level （the aflatoxin Bi concentration in liver, kidney, Longissimus dorsi and Biceps femoris were 1.65 |J.g/kg, 0.76 ug/kg, 1.13 ug/kg, 1.04 ug/kg respectively）, which were less than the most strict EU regulation on toxin residues in animal products （permitted level is 2.0 ppb for aflatoxin Bt and 4.0 ppb for total aflatoxins）. SP has the tendency to reduce aflatoxin residues in pig tissues, but the efficacy was markedly less than NSP.（4） With the addition of 0.3% NSP to AF-containing diet, related parameters returned to normal level, showing beneficial effects of NSP on aflatoxicosis. These findings indicated that NSP had the ability to recover the AF-decreased performance, organ damage and to correct aberrations in related parameters, and NSP can effectively diminish the deleterious effects of AF in growing/finishing pigs, and NSP would be a potential ameliorator of aflatoxicosis in pigs. However, with the addition of 0.3% SP to AF-containing diet, the amelioration effects on pig aflatoxicosis were not as great as NSP.The presumed mechanism of action of NSP is to sequestrate aflatoxin in the gastrointestinal tract and form stable sorption complex, thereby prevent gastrointestinal absorption of toxins, then reduce aflatoxin residues in body tissues, and alleviate adverse effects of AF on pigs.In conclusion, as a new nano-adsorbent, no doubt it would be of great significance toapply NSP to solve the aflatoxin contamination problem, and its application can offer a novel approach to the preventive management of aflatoxicosis in animals and provide an encouraging solution to produce safe and low-residue animal products with AF-contaminated feed.更多还原