预防重于治疗才是避免或减少危害的有效途径霉菌毒素的危害及其控制

导读:黄曲霉素1993年已被世界卫生组织划定为一类致癌物,是一种毒性极强的剧毒物质.在当今养殖业生产中饲料发霉和霉菌毒素引起的动物中毒以及死亡所造成的危害仍然是普遍存在的严重问题.     

动物常见的两种重金属中毒与防治

铅在动物营养学中铅为毒性重金属,是动物中毒的常见因素。其来源主要为日粮、水和空气,畜禽主要通过消化道和呼吸道吸收,在体内骨骼中含量最高(50～70ppm),也是机体的固毒器官。铅是一种慢性蓄积性毒物,排泄速度比较缓慢。铅对动物各种组织均有毒性,主要造成神经系统、造血系统     

饲料霉菌污染的综合防制

霉菌污染是饲料中最突出的微生物污染,污染饲料的霉菌主要有曲霉菌、青霉菌、镰刀霉菌、毛霉菌等.饲料霉变过程中,霉菌生长消耗了饲料中的营养物质,并分解饲料中的蛋白质和糖化淀粉,产生异味. 霉变饲料可导致人畜的急性和慢性中毒或癌肿等,许多原因不明的疾病被认为与饲料或者食品的霉菌污染有关.迄今人类从广泛分布在各种谷物及混合饲料中仅分离出几种霉菌毒素,重要的毒素有黄曲霉毒素、赭曲霉毒素、单端孢霉素、桔霉素和玉米赤霉烯酮,其中黄曲霉毒素的毒性最强,对人和动物都是一种超剧毒物质.孕妇若食入被霉菌毒素污染了的食品,霉菌毒素可通过胎盘祸及胎儿,引起胎儿染色体断裂畸变,有的停止发育.黄曲霉毒素是真菌、曲霉属菌、黄曲霉等的产物,其基本结构为二呋喃氧杂奈邻酮,但化学结构不同的黄曲霉毒素的毒性有所差异,其中B1毒性最大,对所有动物的肝脏都是原发性毒,它与细胞核和线粒体DNA结合,影响蛋白质和类脂的代谢,是揭示肝癌发病机理的模型致癌物.每年饲料等农产品因遭霉菌的侵害而导致的经济损失难以估计,已越来越引起人们的关注.     

减少有害重金属对畜禽机体危害及残留的措施

畜禽由于饲食有害重金属含量超标的饲料、饲料添加剂、违禁药物,饮用工业污水等原因,常引起有害重金属铅、镉、砷、汞等离子对畜禽机体危害或残留。有害重金属离子进入畜禽机体后,通过氧化反应产生有害物质,可使动物机体免疫下降,能引起动物的神经系统、引动系统、消化系统、呼吸系统     

马鹿营养性衰竭症的诊断与防治

营养性衰竭症(Dietetic exhaustion)是由于多种营养物质缺乏所引起的营养不良综合症.其发病因素主要是饲养管理不当,长期饲料供给不足,饲料营养成分不全面或动物机体能量消耗增多等而引起的动物机体新陈代谢、生理功能紊乱和机体衰竭.在动物临床医学上,营养性衰竭症可发生于牛、羊、马、猪等,而马鹿营养性衰竭症的发生比较罕见.     

不同剂量黄曲霉毒素B_1对雏鸭肝线粒体膜通透性的影响

黄曲霉毒素是一种毒性极强的剧毒物质,被世界卫生组织的癌症研究机构划定为1类致癌物[1],黄曲霉毒素主要是对动物肝脏造成危害,急性中毒可引起肝炎,黄疸,肝脏充血、出血、变性和坏死,并伴有严重的血管和中枢神经损伤,动物中毒后几个小时至数天内死亡.黄曲霉毒素慢性中毒畜禽生长不良,饲料转化率降低,死亡率增加,对疾病易感,而且黄曲霉毒素还可以在动物源性食品中残留,给人类健康带来极大的安全隐患[2].     

锌对铅中毒肉仔鸡肝脏脂质过氧化水平的影响

铅是工业生产中普遍应用的化学物质,其毒性已引起人们的普遍重视。人们在对铅毒性的深入研究中发现,低剂量的铅会抑制动物体内抗氧化酶活性,从而使机体脂质过氧化水平加剧。国内外学者关于铅对机体产生毒害的研究有很多,研究的范围也很广,但是铅毒性肝损伤目前尚无特异的生化指标。近年来,有人认为超氧化物歧化酶(SOD)活性可以作为铅接触评价的指标。     

玉米赤霉烯酮所致氧化应激的研究进展

玉米赤霉烯酮是一种真菌毒素,对动物具有生殖毒性、免疫毒性、细胞毒性、遗传毒性,并有促癌作用,还能引起机体的氧化应激。玉米赤霉烯酮广泛存在于饲料和谷物中,能引起动物慢性中毒、机能异常甚至死亡,对畜牧养殖业危害严重。介绍了玉米赤霉烯酮所致的氧化应激作用及其机制,以期为阐明该作用机制涉及的信号转导通路提供理论依据。     

奶牛场的牛奶、饲料中铅污染的检测及分析报告

铅被认为是出现在人类文明史中最严重的环境污染物之一,其生物学意义在于它对人和动物有剧毒,而且是一种累积性的毒物。铅对人体的毒性作用主要是损害骨髓造血系统和神经系统,可引起贫血、高血压、冠心病,引起神经炎,出现运动和感觉障碍,婴幼儿对铅影响更敏感,铅有亲神经性,对儿童尤其是婴幼儿的中枢神经系统易致毒性损害,对儿童智力和行为产生不良影     

红曲霉与健胃中药合生素对小鼠的急性及蓄积毒性试验

试验所研究的复合性饲料添加剂是无公害的新型饲料添加剂,不仅能改善动物胃肠道的环境,使产生致癌物的不良细菌大量减少,促进胃肠消化,增强动物对肠道感染的抵抗能力,提高机体免疫功能,而且在动物体内无残留,对人类健康无危害,对环境无污染,一经研制成功,将有很大的应用价值.     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …     

鸡败血支原体垂直传播模式及其阻断方法

以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

乳酸杆菌作为益生菌广泛用于人和动物。本文综述了乳酸杆菌改善宿主健康的机制。乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道。文章重点讨论了乳酸杆菌表面成分（表面蛋白、脂磷壁酸和肽聚糖）与肠道受体（Ｃ型凝集素受体、Ｔｏｌｌ样受体和 Ｎｏｄ样受体）,阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.