1 前言
霉菌毒素是農(nóng)作物或動(dòng)物性蛋白因霉菌而產(chǎn)生的有毒代謝產(chǎn)物，對(duì)人和動(dòng)物具有廣泛的毒性作用，人或動(dòng)物食入被霉菌毒素污染的食物或飼料后就會(huì)引起霉菌毒素中毒。霉菌種類繁多，約12萬多個(gè)種，其中能產(chǎn)生毒素的有170余種，它們廣泛存在土壤、空氣、水及腐敗有機(jī)物上，范圍遍及全世界。據(jù)聯(lián)合國糧農(nóng)組織（FAO）統(tǒng)計(jì)，全球每年大約有25%的農(nóng)作物不同程度地受到霉菌毒素的污染，約有2%的農(nóng)作物因污染嚴(yán)重而失去飼用價(jià)值，每年由此造成的經(jīng)濟(jì)損失可達(dá)數(shù)千億美元。我國受霉菌毒素污染的情況更為嚴(yán)重，中國農(nóng)科院畜牧所的一項(xiàng)調(diào)查表明，配合飼料中不同程度霉菌毒素的污染達(dá)80%以上，每年由霉菌毒素造成的直接經(jīng)濟(jì)損失達(dá)500億以上。由此可見，霉菌毒素污染已成為影響飼料業(yè)發(fā)展的一大危害，如何認(rèn)識(shí)和防控霉菌毒素已經(jīng)成為能否解決飼料安全的突出問題。
2 霉菌毒素產(chǎn)生原因
在飼料生產(chǎn)過程中，飼料原料、生產(chǎn)工藝、管理等任何一個(gè)環(huán)節(jié)的不合理都可能導(dǎo)致霉菌毒素的產(chǎn)生。
2.1 原料飼料原料霉菌毒素感染主要發(fā)生在田間收割和儲(chǔ)藏過程中。在田間，植物受霉菌感染的因素很多，包括土壤的水分、播種收割的時(shí)期、植病的發(fā)生、雜草、鳥類及害蟲等。在儲(chǔ)藏過程中，飼料倉庫潮濕、鼠害嚴(yán)重，庫區(qū)未經(jīng)常清掃和定期消毒、堆垛不合理、庫存時(shí)間過長、運(yùn)輸時(shí)受到雨淋、曝曬等都容易引起霉變。此外，飼料原料受霉菌感染的程度也與其的成熟度、顆粒的完整度等有較大關(guān)系，成熟度差及破損粒較多的原料易受霉菌的侵染。石永峰等人關(guān)于玉米破碎粒和整粒谷物中串珠鐮孢菌B1毒素的含量的研究表明，碎粒及其它谷物廢料中的霉菌毒素含量是整粒谷物的30倍~500倍。
2.2 加工工藝生產(chǎn)顆粒料過程中，如果設(shè)備選擇不當(dāng)，或使用過程中調(diào)整校對(duì)不準(zhǔn)確，導(dǎo)致顆粒料冷卻時(shí)間不夠或風(fēng)量不足，使得產(chǎn)品水分含量及料溫過高，這樣的產(chǎn)品裝袋后易發(fā)生霉變。未定期清理飼料管道中積存的物料，形成霉積料，脫落后進(jìn)入成品倉和包裝袋，可以導(dǎo)致整批顆粒料霉變。
2.3 管理因素飼料和原料的長期存放，或是存儲(chǔ)地點(diǎn)通風(fēng)不暢、環(huán)境潮濕都易導(dǎo)致霉菌毒素產(chǎn)生。此外，運(yùn)輸過程中日曬、雨淋也容易引起飼料和原料的霉變。
3 霉菌毒素的危害
使用含有霉菌毒素的飼料，將導(dǎo)致畜禽采食量下降、生產(chǎn)性能降低，嚴(yán)重者可直接導(dǎo)致畜禽死亡。
3.1 霉菌毒素對(duì)豬的傷害：改變飼料的養(yǎng)分組成；降低動(dòng)物對(duì)養(yǎng)分的利用率；霉菌毒素誘發(fā)多種動(dòng)物疾病；動(dòng)物組織器官受損，主要危害腎臟、肝臟、生育器官；胚胎的致死率、流產(chǎn)比例增加，外陰道炎，乳房腫大，奶水減少，哺乳仔豬抵抗力下降，母豬淘汰率增加，利用年份減少，公豬精液質(zhì)量下降；免疫系統(tǒng)功能受到干擾，表現(xiàn)免疫力低下、疫苗不能正常發(fā)揮作用，對(duì)疾病易感性高；動(dòng)物采食量下降，胃腸道炎癥，生長速度下降。
3.2 霉菌毒素對(duì)家禽影危害：產(chǎn)蛋率、受精率下降；降低日增重和飼料報(bào)酬；口腔潰瘍，拒食；角色蒼白，蛋黃及皮膚色素差，頭部脫毛，羽毛松亂；免疫機(jī)能下降，死亡率增加。
3.3 霉菌毒素危害機(jī)理：（1）霉菌毒素的毒性危害作用有一個(gè)共同點(diǎn)，那就是免疫抑制。一般認(rèn)為，其作用機(jī)理可能是霉菌毒素與機(jī)體DNA和RNA結(jié)合，抑制其合成進(jìn)而影響機(jī)體蛋白質(zhì)合成，從而降低動(dòng)物免疫力。（2）霉菌毒素通過改變細(xì)胞膜的結(jié)構(gòu)，誘導(dǎo)脂類發(fā)生過氧化反應(yīng)。霉菌毒素通過改變抗氧化劑的濃度，影響抗氧化酶的活性，從而誘發(fā)細(xì)胞的過氧化反應(yīng)。（3）霉菌毒素誘導(dǎo)細(xì)胞程序性死亡。霉菌毒素通過直接影響關(guān)鍵酶或通過改變細(xì)胞中抗氧化劑與氧化劑之間的平衡，尤其是降低細(xì)胞中還原性谷胱甘肽濃度，激發(fā)細(xì)胞程序性死亡。
4 霉菌毒素的檢測(cè)方法
污染飼料的霉菌毒素主要有以下幾種有：黃曲霉毒素B1、赭曲霉毒素、單端霉曲霉毒素、玉米赤霉烯酮、丁烯酸內(nèi)酯、紅色青霉素、黃綠青霉素等，其檢測(cè)方法各異。
4.1 黃曲霉毒素B1（ATFB1）
黃曲霉毒素B1是當(dāng)今世界上發(fā)現(xiàn)最強(qiáng)的致癌物質(zhì)之一，直接對(duì)人類、動(dòng)物的生命安全構(gòu)成危害。許多國家已對(duì)黃曲霉毒素B1的限量標(biāo)準(zhǔn)進(jìn)行提高，并逐漸成為國際貿(mào)易中的技術(shù)壁壘。目前，在食品及飼料ATFB1的國家檢測(cè)標(biāo)準(zhǔn)中提出了三種測(cè)定方法，即薄層層析法、液相色譜法和酶聯(lián)免疫吸附法。薄層層析法是檢測(cè)ATFB1最常用方法，也是我國測(cè)定食品及飼料中ATFB1國家標(biāo)準(zhǔn)檢測(cè)方法，該法設(shè)備簡(jiǎn)單、易于普及，為國內(nèi)外廣泛使用，但該法樣品前處理繁瑣，且提取和凈化效果不夠理想，影響檢測(cè)的精確度。液相色譜法可同時(shí)分離多種黃曲霉毒素，操作簡(jiǎn)便，定量精確，適于大批量樣本分析，但由于儀器昂貴，未能廣泛應(yīng)用。酶聯(lián)免疫吸附法是通過抗黃曲霉毒素B1抗體與酶標(biāo)抗原、待測(cè)抗原的競(jìng)爭(zhēng)免疫反應(yīng)以及酶的催化顯色反應(yīng)相結(jié)合來檢測(cè)ATFB1的含量，前處理簡(jiǎn)單，靈敏度與前兩種相當(dāng)或更高，具有更廣闊的應(yīng)用前景。
4.2 T-2毒素
T-2毒素是常見的污染田間作物和庫存谷物的主要毒素．目前，主要的檢測(cè)方法為液相色譜法、氣相色譜法及免疫法。液相色譜－質(zhì)譜聯(lián)用技術(shù)由于不需要針對(duì)T-2毒素進(jìn)行衍生化處理，具有較高的靈敏度和特異性，目前已成為包括T-2毒素在內(nèi)的單端孢霉烯族真菌毒素的最為廣泛的分析檢測(cè)方法。免疫法、酶聯(lián)免疫吸附分析法具有樣品前處理簡(jiǎn)單快速方便、特異性和靈敏度高、不需要昂貴的儀器設(shè)備等特點(diǎn)，比較適合推廣普及。T-2毒素的免疫檢測(cè)方法由衛(wèi)生部食檢所于1991年建立，方法最低檢出量為1ng/ml，敏感范圍為4ng/ml~1000ng/ml。
4.3 脫氧雪腐鐮刀茵烯醇（DON）
DON又名嘔吐毒素，是一種有很強(qiáng)細(xì)胞毒性、胚胎毒性、一定致畸性、弱致癌性且影響免疫系統(tǒng)的真茵毒素。DON經(jīng)對(duì)甲基苯甲醛噴霧后呈黃色，衛(wèi)生部食檢所于1986年建立了DON薄層層析檢測(cè)方法，1992年建立了免疫檢測(cè)方法，方法最低檢出量為5ng/ml，敏感范圍為5ng/ml~1000ng/ml，該法已批準(zhǔn)為國家標(biāo)準(zhǔn)。小麥、面粉、玉米及玉米粉中脫氧雪腐鐮刀菌烯醇限量標(biāo)準(zhǔn)已于1996年9月1日頒布實(shí)施，最高允許量1000g/kg。
4.4 玉米赤霉烯酮（ZEN）
玉米赤霉烯酮是由禾谷鐮刀菌等菌種產(chǎn)生具有雌激素作用的真菌毒素，能造成動(dòng)物急慢性中毒，引起動(dòng)物繁殖機(jī)能異常甚至死亡，可給畜牧場(chǎng)造成巨大經(jīng)濟(jì)損失。目前，對(duì)ZEN的檢測(cè)方法主要有：薄層色譜測(cè)定方法、高效液相色譜法和酶聯(lián)免疫吸附測(cè)定法。我國于2005年將薄層色譜法列入其國標(biāo)檢測(cè)方法，最低檢測(cè)量為20ng。薄層色譜法對(duì)實(shí)驗(yàn)室儀器設(shè)備要求低，一般的實(shí)驗(yàn)室即可實(shí)施，但此方法操作煩雜，耗時(shí)，測(cè)定時(shí)用目測(cè)半定量，主觀影響較大，靈敏度不高，此方法需大量接觸ZEN標(biāo)準(zhǔn)品，浪費(fèi)毒素，又不利于保護(hù)操作者的健康，不適用于檢測(cè)大批樣品的實(shí)際需要。高效液相色譜法具有準(zhǔn)確度高、靈敏性強(qiáng)、可微量測(cè)定等優(yōu)點(diǎn)，是歐盟國家目前玉米赤霉烯酮毒素檢測(cè)最常用的方法，昂貴的設(shè)備和對(duì)樣品中毒素較高純度的要求，導(dǎo)致檢測(cè)周期長，成本高，無法滿足大批量樣品快速篩選的需要，所以在我國使用受到限制。
4.5 赭曲霉毒素A（OTA）
它是由多種生長在糧食（小麥、玉米、大麥、燕麥、黑麥、大米和黍類等）、花生、蔬菜（豆類）等農(nóng)作物上的曲霉和青霉產(chǎn)生的。至今已有11個(gè)國家制訂了食品（1g/kg～50g/kg）和動(dòng)物飼料（100g/kg～1000g/kg）中OTA的限量標(biāo)準(zhǔn)。我國尚無糧食中OTA的限量標(biāo)準(zhǔn)，其檢測(cè)方法也僅限于薄層色譜法和ELISA法，薄層色譜法為半定量法，ELISA法尚未經(jīng)儀器法驗(yàn)證。
5 存在的問題
中國是世界第一養(yǎng)殖大國，養(yǎng)殖業(yè)受霉菌毒素影響首當(dāng)其沖，據(jù)不完全統(tǒng)計(jì)中國養(yǎng)殖業(yè)由此造成的損失每年都在500億以上。而近年來廣泛流行的動(dòng)物疫情與飼料中霉菌毒素造成免疫抑制有很大的關(guān)聯(lián)，飼料中霉菌毒素已正式被歐美國家認(rèn)定為動(dòng)物疫情源頭。我國霉菌毒素的認(rèn)識(shí)和防控主要存在以下幾方面問題。
5.1 相關(guān)法律法規(guī)不完善，到目前為止在霉菌毒素方面只有黃曲霉毒素列在法令里，而其他霉菌毒素并沒有明確的法律法規(guī)。即便是對(duì)黃曲霉毒素的限定，各國的標(biāo)準(zhǔn)也是不統(tǒng)一的，這種法律法規(guī)必然難以適應(yīng)當(dāng)今的國際性貿(mào)易，一個(gè)全球性的統(tǒng)一的霉菌毒素標(biāo)準(zhǔn)的建立刻不容緩。
5.2 傳統(tǒng)的霉菌毒素檢測(cè)技術(shù)已經(jīng)難以滿足生產(chǎn)一線需求，使得生產(chǎn)單位在面對(duì)各種原材料霉菌污染時(shí)一直處于滯后控制的被動(dòng)局面。目前社會(huì)所公認(rèn)并廣泛使用的霉菌毒素檢測(cè)技術(shù)主要有：一類是生物學(xué)檢測(cè)法，包括種子發(fā)芽試驗(yàn)、嘔吐試驗(yàn)和皮膚毒性試驗(yàn)等，但是檢測(cè)結(jié)果的時(shí)效性很差；另一類是理化檢測(cè)法，薄層色譜法（TLC）和高效液相色譜法（HPLC）。TLC雖然簡(jiǎn)便，但靈敏度差；HPLC雖然靈敏度高，但樣品處理煩瑣，操作復(fù)雜，儀器昂貴，標(biāo)準(zhǔn)品耗用大。還有一類是利用免疫化學(xué)原理開展的實(shí)驗(yàn)室快速檢測(cè)法，如ELISA方法——-即酶聯(lián)免疫法，由于種種條件的限制也難以滿足生產(chǎn)一線現(xiàn)場(chǎng)快速檢測(cè)的要求。
5.3 我國霉菌脫毒技術(shù)尚處于不成熟狀態(tài)，對(duì)霉菌毒素、去毒方法研究較晚，還沒有較為清楚系統(tǒng)的認(rèn)識(shí)。廣泛為人所接受并使用的物理、化學(xué)和生物學(xué)方法降解和吸附飼料中霉菌毒素，很難在飼料中大量、有效并且低成本的實(shí)現(xiàn)。
6 建議
霉菌毒素能夠通過食物鏈對(duì)人類健康造成重大威脅，在實(shí)際生產(chǎn)中我們要對(duì)其危害要有清晰的認(rèn)識(shí)，積極采取措施從多種途徑多種角度入手，減少霉菌毒素對(duì)動(dòng)物健康及生產(chǎn)性能的不利影響。我國對(duì)霉菌毒素的研究起步較晚，我國飼料衛(wèi)生標(biāo)準(zhǔn)GB13078-2002年才第一次對(duì)飼料中的黃曲霉B1有了安全限量標(biāo)準(zhǔn)，2007年才對(duì)嘔吐毒素公布了限量標(biāo)準(zhǔn)。我國許多養(yǎng)殖業(yè)生產(chǎn)者對(duì)霉菌毒素給生產(chǎn)造成的危害認(rèn)識(shí)不足，存在著片面的甚至錯(cuò)誤的觀點(diǎn)，它給生產(chǎn)造成的無形損失也是十分驚人的。針對(duì)我國實(shí)際生產(chǎn)狀況，現(xiàn)提出以下幾點(diǎn)建議。
6.1 提高對(duì)霉菌毒素的認(rèn)識(shí)，建立溯源體系。加強(qiáng)飼料生產(chǎn)企業(yè)從業(yè)人員的科學(xué)文化水平，提高其對(duì)霉菌毒素危害性的認(rèn)識(shí)，建立針對(duì)性有側(cè)重點(diǎn)的霉菌毒素控制體系，避免花費(fèi)過多精力和金錢卻得不到很好的效果。從采購、生產(chǎn)、儲(chǔ)存、運(yùn)輸?shù)拳h(huán)節(jié)進(jìn)行控制，對(duì)每一批次飼料的原料來源、加工工藝條件、成品儲(chǔ)存和運(yùn)輸過程加強(qiáng)監(jiān)管，進(jìn)行詳細(xì)記錄，建立可跟蹤可追溯的控制系統(tǒng)。
6.2 完善霉菌毒素相關(guān)法律法規(guī)，建立一套完整的霉菌毒素?cái)?shù)據(jù)庫。修正國家現(xiàn)有的飼料毒素標(biāo)準(zhǔn)，把真正危害中國飼料工業(yè)的主要毒素黃曲霉毒素、煙曲霉毒素列入法定標(biāo)準(zhǔn)，把次要的毒素如嘔吐毒素、玉米赤霉烯酮、T-2毒素、DAS毒素列入?yún)⒖紭?biāo)準(zhǔn)，霉菌毒素限量標(biāo)準(zhǔn)盡可能與國際標(biāo)準(zhǔn)接軌，避免對(duì)外貿(mào)易過程中其他國家利用技術(shù)壁壘對(duì)我國農(nóng)業(yè)造成阻礙。分季度和年度對(duì)大宗原料、飼料進(jìn)行霉菌毒素批量檢測(cè)，實(shí)時(shí)監(jiān)控毒素的陽性檢出率、含量水平、陽性中值。通過統(tǒng)計(jì)分析，總結(jié)在不同時(shí)節(jié)霉菌毒素含量隨天氣、溫度、地域差異的變化，分類設(shè)定不同區(qū)域的不同原料霉菌毒素的監(jiān)控種類和毒素含量范圍，建立一套完整的霉菌毒素?cái)?shù)據(jù)庫，為采購原料提供霉菌毒素預(yù)警，同時(shí)指導(dǎo)原料在配方中的合理選擇和有效搭配。
6.3 利用現(xiàn)代生物學(xué)技術(shù)，生產(chǎn)出一種能夠快速精準(zhǔn)并且定量的檢測(cè)霉菌毒素產(chǎn)品。在現(xiàn)有霉菌檢測(cè)技術(shù)基礎(chǔ)上，應(yīng)用免疫學(xué)檢測(cè)方法將便攜式霉菌毒素檢測(cè)試劑管大量投入生產(chǎn)，并廣泛應(yīng)用于生產(chǎn)一線現(xiàn)場(chǎng)的快速檢測(cè)，使得霉菌毒素檢測(cè)可以快速精確并且簡(jiǎn)便的實(shí)現(xiàn)。
6.4 建立理想霉菌毒素吸附劑模型，開發(fā)新型復(fù)合霉菌毒素脫毒劑。理想霉菌毒素吸附劑應(yīng)有以下幾點(diǎn)特征：具有廣譜的霉菌毒素吸附特性；可以通過糞便排出霉菌毒素；可改善家畜的生產(chǎn)性能；能恢復(fù)機(jī)體器官功能；可以恢復(fù)免疫功能；能向動(dòng)物提供必需養(yǎng)分；吸附劑不能促生長劑，促生長的特性可能會(huì)掩蓋霉菌毒素的中毒癥狀。理想的毒素吸附劑應(yīng)具備只吸附毒素，不吸附營養(yǎng)物的特點(diǎn)。理想霉菌毒素吸附劑模型建立為今后霉菌毒素吸附劑研發(fā)指明了方向，為未來新型霉菌毒素吸附劑提供了必要條件。受地域環(huán)境和氣候條件等因素的影響，常常是多種霉菌毒素同時(shí)在飼料中出現(xiàn)，使得霉菌毒素引起的有害影響更加復(fù)雜。任何一種單一的吸附劑都不能將所有霉菌毒素都吸附，因?yàn)椴煌咕舅胤肿佑胁煌睦砘再|(zhì)，因此通過將不同類型的吸附劑進(jìn)行適當(dāng)配比研發(fā)出一種新的復(fù)合型霉菌毒素吸附劑是未來發(fā)展趨勢(shì)。
霉菌毒素對(duì)畜禽生長、畜產(chǎn)品及人類健康造成危害以及經(jīng)濟(jì)上的重大損失，這已是無可爭(zhēng)議的事實(shí)。近幾年隨著原料價(jià)格不斷攀升，越來越多糧食副產(chǎn)物被使用，使得飼料中霉菌毒素問題愈演愈烈。因此，完善我國的飼料霉菌毒素標(biāo)準(zhǔn)體系有利于解決飼料安全問題，保障百姓健康，保護(hù)生態(tài)環(huán)境，實(shí)現(xiàn)飼料工業(yè)持續(xù)良性發(fā)展，提高我國飼料和畜禽產(chǎn)品在國內(nèi)國際市場(chǎng)的競(jìng)爭(zhēng)力，更加從容應(yīng)對(duì)市場(chǎng)給我們帶來的機(jī)遇和挑戰(zhàn)。
The English version
1 introduction
Mycotoxins are crop or animal protein for mould and produce toxic metabolite, for people and animals have toxic effects, person or animal feed into the mycotoxin contamination of food or feed after can cause mold toxin poisoning. There are many different kinds of mold, about more than 120000 species, which can produce toxin has more than 170 kinds, they widely exist on organic matter, soil, air, water and corruption throughout the world. According to the United Nations food and agriculture organization (FAO), the world each year, about 25% of the crop from mycotoxin contamination in different degrees, about 2% of the crops because of serious pollution and loss of forage value, the resulting economic losses can be up to hundreds of billions of dollars every year. The mycotoxin contamination is more serious in our country, according to a survey by the Chinese academy of agricultural sciences' animal husbandry, compound feed in different degrees of mycotoxin contamination above 80%, and each year by mycotoxins caused direct economic losses of more than 50 billion. Thus, mycotoxin contamination has become a big threat to affect the feed development, how to understand and control mycotoxin has become can solve the problems of feed safety.
2 mycotoxin causes
In the process of feed production, feed raw materials, production technology, management and so on any one link may result in unreasonable mycotoxin produced.
2.1 raw material feed ingredients mycotoxin infection occurred mainly in the field in the process of harvesting and storing. In the field, the plant by fungus infection of many factors, including soil moisture, seeding the harvest period, the occurrence of plant disease, weeds, birds and insects, etc. In the process of storage, warehouse feed moisture, severe rat, regular cleaning and disinfection regularly reservoir area, unreasonable stacking, storage time is too long, transported by rain and exposure is likely to lead to mildew. In addition, feed raw materials affected by the degree of fungal infection and its maturity, grain of integrity has great relations, such as low maturity and damaged grain more vulnerable to infection of mold materials. Shi Yongfeng fragment of grain and whole grain, and others about the corn beaded B1 of fusarium oxysporum toxin content in the study, debris and other grains of mycotoxin content in waste is whole grain, 30 ~ 500 times.
2.2 processing technology in the process of the production of granular material, if improper equipment selection, or adjust the proofreading is not accurate, in use process cause grain cooling time is not enough or insufficient air volume, makes the product moisture content and temperature is too high, so that products are prone to mildew after bagging. Did not accumulate in the regular cleaning of feed pipe materials, forming mould material, fall off after the finished products warehouse and packing bag, can lead to the whole batch of grain mildew.
2.3 management long stored, of the material and the factors of feed or storage location ventilation, environmental humidity is easy to cause the mycotoxin. In addition, the transport process in the sun, the rain also easy to cause of the material and the feed mildew.
3 the dangers of mycotoxin
Using containing mycotoxins in feed, resulting in a decline in livestock and poultry feed intake, production performance, severe cases can be directly led to the deaths of livestock and poultry.
3.1 mycotoxin damage to the pig: change of feed nutrient composition; Reduce animal utilization of nutrients; Mycotoxin induced by a variety of animal diseases; Animal tissues and organs damaged, the main harm kidneys, liver, reproductive organs; Embryonic lethality, rising rates of miscarriage, vaginitis, breast enlargement, milk, lactation piglet resistance drop, sow elimination rate increases, the use of year decrease, boar semen quality drop; Disturbance of immune system function, low immunity, the vaccine can't normal work, high susceptibility to disease. Animal feed intake down, gastrointestinal inflammation and growth rate decline.
3.2 mycotoxin shadow damage of poultry: laying rate, fertilization rate decline; Reduce the daily gain and feed remuneration; Oral cavity ulcer, refus feeds; Role is pale, egg yolk, or skin pigment is poor, the head hair removal, feathers loose chaotic; Immune function decline, increased mortality.
3.3 mycotoxin harm mechanism: (1) the toxicity of harmful effects of mycotoxin have one thing in common, that is immunosuppression. It is generally believed that the mechanism may be mycotoxin combined with the body's DNA and RNA, inhibit the synthesis, in turn, affect the body protein synthesis, thereby reducing animal immunity. (2) the mycotoxin by changing the structure of the cell membrane, induced lipid peroxidation. Mycotoxin by changing the concentration of antioxidants, influence the activity of antioxidant enzymes, which induce cell peroxidation. (3) the mold toxin induced programmed cell death. Mycotoxin by directly affects the key enzyme or by changing the balance between cell antioxidants and antioxidant, especially lower reducing GSH concentration in the cell, stimulate the programmed cell death.
4 mycotoxin detection method
Contaminated feed mycotoxins basically has the following kinds: aflatoxin B1, ochre and aspergillus toxin, single-ended mould aspergillus toxin, corn gibberellic ketene, crotonic acid lactone, yellow, green, red, penicillin penicillin, etc., the different test method.
4.1 aflatoxin B1 (ATFB1)
Aflatoxin B1 is one of the strongest carcinogens found in the world today, directly to human and animal life safety hazards. Many countries have to improve the standard of set limit to aflatoxin B1, and gradually become technical barriers in international trade. At present, in food and feed ATFB1 national testing standards, puts forward three methods for determining the thin layer chromatography, liquid chromatography (HPLC) and enzyme-linked immunosorbent method. Thin layer chromatography is the most commonly used method in detecting ATFB1, also is our country in food and feed ATFB1 national standard testing method, the equipment is simple, easy to popularize, is widely used at home and abroad, but the sample pretreatment, extraction and purification effect is not ideal, and influence the accuracy of the test. Liquid chromatography separation at the same time a variety of aflatoxin, easy to operate, quantitative precision, suitable for large sample analysis, but due to the expensive instrument, failed to a wide range of applications. Enzyme-linked immunosorbent method is by aflatoxin B1 antibody and enzyme standard antigen, competition for the antigen immune reaction and enzyme catalytic chromogenic reaction combined to detect the content of ATFB1 pretreatment is simple, and the former two kinds of equal or higher sensitivity, it has a wide application prospect.
4.2 T - 2 toxin
T 2 toxin is a common field crops and grain inventory main toxin pollution. At present, the main detection methods for liquid chromatography, gas chromatography and immunoassay. Liquid chromatography - mass spectrometry technology due to no need for T - 2 derivatization toxins, and has high sensitivity and specificity, which is a single ended, including T 2 toxin, spore of alkene mycotoxin analysis detection method is the most widely. Immunoassay, enzyme-linked immunosorbent analysis method is convenient and fast sample preparation is simple, high specificity and sensitivity, don't need expensive equipment etc, and is suitable for popularization. T 2 toxin immune detection method was established in 1991 by the ministry of health food inspection, detection method is the minimum quantity of 1 ng/ml, the sensitive range of 4 ng/ml to 1000 ng/ml.
4.3 DNA snow sickle wormwood enol (DON)
DON and vomiting toxins, poisonous to the cells is a kind of strong, weak embryo toxicity, teratogenicity, carcinogenicity and the liposome toxins that affect the immune system. DON yellow after spray to methyl benzene formaldehyde, was established in 1986 by the ministry of health food inspection DON thin-layer chromatography detection method, immune detection method is established in 1992, the detection method is the minimum quantity is 5 ng/ml, sensitive range for 5 ng/ml to 1000 ng/ml, the law has approved as the national standards. DNA in wheat, flour, corn and corn flour snow sickle germ enol evaluation standard was issued in September 1, 1996, the highest allowances 1000 g/kg.
4.4 corn gibberellic ketene (ZEN)
Corn gibberellic ketene is by the valley of grain sickle bacteria strains produce estrogen effect such as fungal toxins, can cause acute or chronic poisoning animals, animal reproduction function abnormality and even death, can be caused huge economic losses to livestock farm. Currently, the main detection methods of ZEN: thin layer chromatographic method, high performance liquid chromatography (HPLC) method and enzyme linked immunosorbent assay method. In 2005, our country will thin layer chromatography (TLC) listed in the national standard test method, minimum detectable amount to 20 ng. Thin layer chromatography (TLC) requirements for laboratory instruments and equipment is low, general laboratory can be implemented, but this method all the operation, time-consuming and determination in the visual semi-quantitative, subjective influence is bigger, the sensitivity is not high, this method requires a lot of contact with ZEN standard, waste toxins, and not conducive to protect the health of operators, is not suitable for detection of the actual need of the sample. High performance liquid chromatography (HPLC) method with high accuracy, strong sensitivity, determination of trace etc, and is the eu countries are corn gibberellic ketene toxin detection is the most commonly used method, expensive equipment and the requirement of high purity of samples toxin, lead to test cycle is long, cost is high, can't meet the needs of the rapid screening of large sample, so use is restricted in our country.
4.5 ochratoxin A (OTA)
It is made of a variety of growth in grain (wheat, corn, barley, oats, rye, rice and millet class, etc.), peanuts, vegetables (such as beans) produced by aspergillus and penicillium on the crops. With 11 countries formulate food (1 g/kg ~ 50 g/kg) and animal feed (100 g/kg to 1000 g/kg) in the standard of set limit to OTA. There is no food in the standard of set limit to OTA in China, and its detection methods are limited to thin layer chromatography (TLC) and ELISA method, thin layer chromatography (TLC) for the semi-quantitative method, ELISA method has not been verified by instrument method.
Five problems
China is the world's first breeding powers, bear the brunt of the breeding industry affected by the mycotoxin, according to incomplete statistics China farming the resulting loss in more than 50 billion each year. And has been widely popular in recent years animal outbreaks and mycotoxins in feed immunosuppression caused by a lot of associations, mycotoxins in feed source of animal epidemic situation has officially been recognized as the European and American countries. Our understanding and the prevention and control of mycotoxin mainly exist the following problems.
5.1 relevant laws and regulations is not perfect, so far only in terms of mycotoxin aflatoxins are listed in the law, while other mycotoxin and there is no explicit laws and regulations. Even to the demarcate of the aflatoxin, national standard is not unified, the laws and regulations will be difficult to adapt to today's international trade, a global the establishment of a unified standard of mycotoxin is urgently needed.
5.2 traditional mycotoxin detection techniques have been difficult to meet the demand of production line, make the production units in the face of all kinds of raw materials mold pollution has been lagging the control of the passive situation. At present socially recognized and widely used mycotoxin detection techniques mainly include: one kind is biology assay, including seed germination experiment, vomiting and skin toxicity test, etc., but the timing of the test results is very poor; Another kind is the physical and chemical tests, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). TLC, although simple, the sensitivity difference; HPLC, while high sensitivity, the sample handling troublesome, complex operation, instrument is expensive, standard cost. There is one kind is using immunochemical principle to carry out laboratory tests quickly, such as ELISA method -- - namely, enzyme-linked immunoassay, due to various constraints is also difficult to meet the requirements of rapid detection of the scene production line.
5.3 mould detoxification technology in China is still in its immaturity, mycotoxins, methods to poison study late, has not been a clear system of acknowledgement. Be widely accepted and use of physical, chemical and biological degradation and adsorption mycotoxins in feed, it is difficult to a lot in the feed, the realization of effective and low cost.
Six Suggestions
Mycotoxin could poses a major threat to human health through the food chain, in the actual production we must has a clear understanding of the harm from a variety of ways a variety of angles, take active measures to reduce the mycotoxin on animal health and production performance. Study of mycotoxin starts late in our country, our country feed hygiene standard GB13078-2002 years for the first time have on aflatoxin B1 in the feed safety evaluation standard, in 2007 to vomiting toxins released evaluation standard. Many aquaculture producers of mycotoxins in China to produce the damage is insufficient, there exists a one-sided or wrong ideas, it gives the invisible loss caused by production is also astonishing. In view of the actual production situation in China, put forward the following Suggestions.
6.1 to improve understanding of mycotoxin, establish the traceability system. To strengthen the scientific and cultural level of feed production enterprise employees, improve their awareness of mycotoxin harmfulness, establish targeted focus mycotoxin control system, to avoid spending too much energy and money is not very good effect. From procurement, production, storage, transportation, raw material source, for every batch of feed processing technology conditions, finished product storage and transportation process to strengthen supervision, carries on the detailed record, can track the traceability of the control system is established.
6.2 improve mycotoxin relevant laws and regulations and establish a complete set of mycotoxin database. Revised national existing standard of feed toxin, the real harm China's feed industry main toxins aflatoxin, smoke aspergillus toxin in the legal standard, the secondary toxins such as vomiting toxins, corn gibberellic ketene, T 2 toxin, DAS toxins listed in reference standard, evaluation standard as far as possible in line with international standards, mycotoxin avoid other countries use technical barriers in the process of foreign trade of our country agriculture. Quarterly and annual of commodities, feed mycotoxins batch detection, real-time monitoring of toxins in the positive detection rate, levels and positive values. Through statistical analysis, summarized in different time of mycotoxin content varied with the change of weather, temperature, regional differences, different materials in different areas of the classification set mycotoxin toxin and the types of the monitoring scope, establish a complete set of mycotoxin database, provides the mycotoxin warning for purchasing raw materials, and to guide rational selection of raw materials in the formula and the effective collocation.
6.3 use of modern biological technology, produce a kind of can fast accurate and quantitative detection of mycotoxin products. On the basis of the existing mold testing technology, application of immunological detection method will portable mycotoxin detection reagent tube a lot into production, and is widely applied in rapid detection of production line, makes the mycotoxin detection can be quickly and accurately and easy implementation.
6.4 ideal mycotoxins adsorbent model is set up, develop new compound mycotoxin poison. Ideal mycotoxins adsorbent should have the following characteristics: has a broad spectrum of mycotoxin adsorption characteristics; Through its droppings mycotoxins; To improve livestock production performance; To restore the body organ function; Can restore immune function; Can provide you with the necessary nutrients to animals; Adsorbent can't growth promoting agent, the characteristics of the growth may mask the mold toxin poisoning symptoms. Poison ideal adsorbent should have only the adsorption, adsorption characteristics of nutrients. Ideal mycotoxins adsorbent model pointed out the direction of mycotoxins adsorbent for the future research and development, new mycotoxins adsorbent provides necessary conditions for the future. Affected by factors such as geographical environment and climate conditions, is often a variety of mycotoxins in feed at the same time, causing the harmful effects of mycotoxin more complicated. No single adsorbent can all mycotoxin adsorption, because different mycotoxin molecules have different physical and chemical properties, so through the different types of adsorbent proper proportion has developed a new kind of compound mycotoxin adsorbent is the future development trend.
Mycotoxin on growth of livestock and poultry, livestock, and cause harm human health, and significant economic losses, this is beyond dispute. As the raw material price is rising in recent years, more and more food by-product is used, mycotoxins in feed problems worse. Therefore, consummates our country feed mycotoxins standards system is helpful to solve the problem of feed safety, safeguard people's health, protect the ecological environment, realize the benign development of feed industry continue to improve the feed and livestock and poultry products in domestic and international market competitiveness, more easy to cope with the market brings us opportunities and challenges.
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