硒中毒

1817年,瑞典化学家Berzelius发现了氧组元素硒(Selenium).在以后的一个多世纪中,硒一直被认为是一种对人畜有毒的物质.直到1957年,Schwarz和Foltz发现从酿酒酵母中分离出来的生物活性因子Ⅲ(即硒),能预防老鼠因维生素E缺乏而引起的肝坏死;同年,这种作用很快由Patterson等和Schwarz等在预     

必需微量元素硒的研究进展

微量元素硒于1817年被瑞典化学家Berzdius首次发现并命名，直到1958年Schwarz等研究发现硒具有抗氧化作用，可防止犊牛白肌病。其营养作用才引起人们的重视，1973年Rofruek等发现硒是谷胱甘肽过氧化物酶的必需成分；80年代初，杨光圻等报道了硒与克山病关系研究的成果，加深了人们对硒的营养生物学功能的认识。至此，硒是人和动物必需的微量营养元素这一观点得到全球科学家的一致公认，推动了硒与人体健康关系的研究。从而，微量元素硒逐渐引起了人们的重视，其研究也成为当前的热点问题。     

仔猪伪狂犬病伴发硒缺乏症的诊治

近年来,随着猪肉行情的上涨,我国养猪规模逐渐扩大,猪群的流动和种猪调运异常频繁,猪伪狂犬病日趋成为严重危害猪群的疾病之一。猪伪狂犬病是由伪狂犬病病毒引起人畜共患的急性传染病,随着患病猪只年龄的不同,其临床症状也不尽相同。哺乳仔猪出现发热、神经症状、消化道症状,病死率极高;成年猪呈隐性感染,上呼吸道呈卡他性症状;妊娠母猪则发生流产、死胎、木乃伊胎、延迟分娩、弱仔增多等现象。而硒缺乏症是由硒或硒和维生素E缺乏所引起的一种营养障碍综合征。该病发病率和死     

酵母硒抗病毒感染研究进展

微量元素硒在抗病毒感染疾病中,与宿主抗氧化能力和免疫应答的改变有关。一系列的研究表明,硒缺乏的人或动物更有容易受到病毒的入侵,甚至引起病毒毒力的增强和病毒基因的变异。营养与病毒感染的关系已成为目前研究的热点。文章就酵母硒抗病毒感染、促进机体的免疫功能等方面做一综述,为酵母硒的应用以及营养与病毒感染的关系研究提供借鉴。     

防治狐、貉、貂妊娠中断的措施

<正>近年来,由妊娠中断使狐、貉、貂等毛皮动物受胎率降低、产仔数减少导致繁殖失败的病例越来越多,严重影响了广大养殖户的生产效益。妊娠中断主要表现为死胎、烂胎、木乃伊胎、流产、早产及空怀等。1引起妊娠中断的原因1.1饲料营养不全主要表现为饲料营养不全,不能满足妊娠期间的营养需求,引起营养代谢失调、营养需要达不到标准,导致妊娠中断;还有维生素缺乏和微量元素锌、硒等缺乏导致妊娠中断;也有饲喂发霉变质饲料     

鸡硒-维生素E缺乏症的诊治

鸡硒-维生素E缺乏症是鸡在生长过程中,因饲料中缺乏硒和维生素E而引起的一种营养代谢疾病。该疾病容易引起鸡营养性肌营养不良、渗出性素质和胰腺变性等症状。因此,养殖户们要加强该病的防治措施。     

硒的生态学——兼谈我国的高硒区

硒的早期历史被认为是对人畜十分有害的元素,1957年发现少量的硒对防治动物肝坏死是十分必要的。1973年世界卫生组织宣布:硒是人和动物生命必需的微量元素,缺乏时人畜健康遭到严重损害。已知缺硒遍及     

饲料中添加硒的注意事项

硒是畜禽维持生长和生育力所必需的微量元素,缺硒易引起畜禽多种疾病,甚至造成大批死亡。但另一方面,硒又是一种剧毒物质,使用时必须十分慎重。在饲料中添加硒时必须注意以下几个方面:一、只能用硒酸钠或亚硒酸钠作饲料添加剂。二、硒酸钠和亚硒酸钠是剧毒物质,易引起人畜中毒,应妥善保管,专人负责。三、限制用量:(1)鸡、鸭、猪、羊、肉牛、奶牛的全价饲科中含硒量不得超过0.1ppm(即1公斤混合料中添加硒0.1毫克)。(2)仔猪开食前期料与开食料中含硒量不得超过0.3ppm。(3)火鸡全价饲料中含硒置不得超过     

微量元素硒对家畜的营养作用

微量元素种类很多,但一般指硒、钴、铁、锌、锰、铜、碘等元素,其中硒是家畜的一种必需营养素,它的生理功能及在动物体内代谢过程等问题,正越来越引起动物营养学家和病理学家的重视。现已证明家畜有一些疾病是由于缺硒所引起的,在世界各地均有发生,给畜牧业带来了严重的危害,缺硒已成为世界性的畜牧业问题。因此,探讨硒对家畜的营养作用十分重要。本文就微量元索硒对家畜的营养作用中的几个问题概述如下。一、微量元素硒的生理功能瑞典化学家 Berzelius 于1817年发现此种元素,并命名为硒(Se)。1930年发     

鸡硒-维生素E缺乏症的诊断与防治要点

<正>鸡硒-维生素E缺乏症是由于日粮中硒-维生素E供给不足或消化吸收障碍,引起的以脑软化、渗出性素质及肌营养不良为主要病变特征,且表现形式多样的营养代谢性疾病。严重时,可造成大     

日粮硒水平对北京鸭生长及发病死亡的影响

将1日龄北京雏鸭180只按体重随机分成6组,每组30只。在低硒日粮中补充亚硒酸钠,调正各组日粮含硒水平为0.01,0.03,0.05,0.10,0.30及0.50ppm,测定体重,组织硒含量及血液谷胱甘肽过氧化物酶活性,研究日粮不同硒水平对北京鸭生长及发病死亡的影响。结果表明,日粮含硒在0.03ppm以下时,北京鸭死亡率高,增重差,缺硒病变严重。日粮含硒在0.05ppm以上才能维持北京鸭不发生缺硒死亡,其中以0.30ppm对生长发育更为适宜。     

硒对镉在鸡体内分布的影响

本试验按照在日粮中分别添加45ppm Cd、45ppm Cd 5ppm Se、45ppm Cd 10ppmSe、45ppm Cd 15ppm Se和仅饲喂基础日粮的处理方法,将成年蛋鸡100只分成5组,对各组鸡在试验40、60、90、120d不同时期肝、肾、心、肌肉组织硒、镉的含量进行了检测.结果表明,硒可降低镉在组织器官的蓄积,且在本试验条件下,随着日被硒水平的增加,其降低效果超明显;硒对镉损害的保护效应,主要取决于日粮中适宜的Sc/Cd摩尔比值,其最适Se/Cd摩尔比约为1:3.     

Comparative effects of high dietary levels of organic and inorganic selenium on selenium toxicity of growing-finishing pigs

This experiment evaluated the effect of high dietary Se levels using organic or inorganic Se on the selenosis responses in growing-finishing swine. A 2 x 4 factorial arrangement of treatments in a randomized complete block design was conducted in two replicates. Sodium selenite or Se-enriched yeast was added at 5, 10, 15, or 20 ppm Se to corn-soybean meal diets. A basal diet without added Se was a ninth treatment group. Ninety crossbred barrows initially averaging 24.7 kg BW were allotted at five pigs per pen. Pigs were bled at 3-wk intervals and plasma Se, glutathione peroxidase (GSH-Px) activity, glutamic oxalacetic transaminase (PGOT), hemoglobin, packed cell volume, and blood cell Se concentration were measured. After 12 wk, pigs were killed and various tissues and bile were collected for Se analyses. Pig body weights, daily gains, and feed intakes were similar for both Se sources when provided at < or = 5 ppm Se, but each measurement declined in a different manner for each Se source as the dietary Se level increased. The decline was more rapid when the inorganic rather than organic Se source was fed, resulting in interaction responses (P < 0.01). Hair loss (alopecia) and separation of the hoof at the coronary band site occurred at > or = 10 ppm inorganic Se but at > or = 15 ppm organic Se level. Plasma GSH-Px activity increased (P < 0.01) when high dietary Se levels of either Se source was fed. Plasma and blood cell Se increased at each period as dietary Se level increased (P < 0.01) and was greater when organic Se was provided (P < 0.05). Blood cell Se concentration reached a plateau when inorganic Se, but not when organic Se, was fed and increased as the experiment progressed. This resulted in a three-way interaction (P < 0.01). Plasma GOT activity at the 12-wk period was elevated when inorganic Se was provided at > or = 15 ppm Se but not when organic Se was fed, resulting in an interaction (P < 0.05). Tissue Se concentrations increased as dietary Se level increased and when organic Se was provided, resulting in interaction responses (P < 0.05). Bile was a yellow color when the basal diet was fed but was dark brown at > 10 ppm inorganic Se and at 20 ppm when organic Se was provided. Bile Se increased as dietary Se level increased (P < 0.01). These results suggest that dietary Se from inorganic or organic sources was toxic at > or = 5 ppm Se, but subsequent selenosis effects were more severe and occurred sooner when sodium selenite was the Se source.     

雏鹅实验性缺硒病及高锌对缺硒影响的病理学研究

１００只一日龄雅安本地白鹅随机分三组，分别喂给低Ｓｅ（含Ｓｅ０．０３１６ｐｐｍ）、低Ｓｅ高Ｚｎ（含Ｓｅ０．３１６ｐｐｍ，Ｚｎ１５００ｐｐｍ）和补Ｓｅ（含Ｓｅ０．０３１６ｐｐｍ＋０．３ｐｐｍ）饲粮，饲喂８周。低Ｓｅ组和低Ｓｅ高Ｚｎ组于第３周至第６周发病、死亡高峰。临诊症状表现为精神沉郁、食欲降低、腹泻、脱水和生长缓慢。特征性的损害为肌胃和骨骼肌变性、坏死和钙化；胰腺萎缩、变性、坏死和纤维化；淋巴免疫     

Biochemical and physiological indicators of selenium status in animals

Selenium (Se) concentrations in animal tissues vary with the tissue and with the amount and chemical form of Se in the diet. In cattle, sheep and swine, Se concentrations rank in kidney greater than liver greater than heart greater than skeletal muscle greater than adipose tissue. Selenium concentrations (wet basis) in skeletal muscle of swine (.03 to .52 ppm) reflect natural dietary Se concentrations ranging from .03 to .49 ppm. Inorganic Se additions to diets low in natural Se (.05 ppm) increase skeletal muscle Se concentrations until dietary Se levels are adequate. After a period of Se repletion, skeletal muscle Se concentrations should be at least .08 ppm on a wet basis. Selenium concentrations in plasma, serum or whole blood are also related to inorganic Se intake and rise in direct relation to each other in the deficient to adequate range. Plasma or serum Se concentrations of .08 to .12 ppm are consistent with dietary adequacy. Selenium-dependent glutathione peroxidase (GSH-Px) activity of plasma or whole blood may also be used to assess Se status in some animals since plasma or whole blood Se concentrations are positively correlated with GSH-Px activity in animals that are low to adequate in dietary inorganic Se. However, inter-laboratory variation in GSH-Px values is large, and it is doubtful that limits of normalcy developed in one laboratory are applicable in others. In certain tissues it is important to distinguish between GSH-Px and glutathione (GSH) S-transferases, which can reduce organic hydroperoxides but which are not Se-dependent. It is also important that the instability of GSH-Px be considered so that losses in activity during handling and storage may be minimized. Urinary Se excretion and Se retention as percentages of Se intake may be helpful in assessing Se status when facilities for metabolism studies are available.     

Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.     

Effect of inorganic selenium supplementation on selenosis in postweaning swine

A total of 72 pigs weaned at 4 wk of age were allotted by litter and weight to nine treatment groups and fed 20% protein cornsoybean meal diets supplemented with various levels of inorganic Se during a 37-d postweaning period. Eight groups were fed diets with 0, 2.5, 5.0, 7.5, 10, 15, 20 or 40 ppm Se provided as sodium selenite, while a ninth was offered the 0- and 40-ppm Se diets in separate feeders. Gains and feed intakes were similar during the trial for the 0- and 2.5-ppm Se diets. Both gain and feed intake declined as dietary Se levels above 5.0 ppm increased. At a dietary Se concentration of 40 ppm, feed consumption ceased within a few days of feeding and subsequent gains were negative. Pigs offered both the 0- and 40-ppm Se diets preferentially selected the basal as compared with the 40-ppm Se diet. When the feeders were switched at 28 d they refused the 40-ppm Se diet within a few hours. After a 17-d period, pigs fed the 20- or 40-ppm Se diet were not able to coordinate their walk, with many exhibiting an inability to stand. Alopecia was demonstrated in pigs fed 15 ppm Se or higher at 17 d, but was evident in the 5.0-ppm group at 37 d. At the termination of the trial, abnormal hoof formation at the coronary band was evident in pigs fed diets containing Se greater than or equal to 5 ppm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of organic and inorganic selenium sources and levels on sow colostrum and milk selenium content

A study was conducted to evaluate the short-term effects of feeding two dietary Se sources at various Se levels on the transfer of Se to the dam's milk and nursing pig. Six dietary treatments were arranged in a 2 x 2 factorial arrangement with two additional treatments in a randomized complete block designed experiment. Inorganic (sodium selenite) or organic (Se-enriched yeast) Se sources were added to the diet at .15 or .30 ppm Se. A non-Se-fortified corn-soybean meal basal diet served as a negative control, and a sixth group was fed .15 ppm Se from both inorganic and organic Se sources. A total of 43 sows were fed their treatment diets at 2.2 kg/d from 6 d prepartum to parturition and at full feed through a 14-d lactation period. Ten sows were initially bled at 6 d prepartum, and three sows and three pigs from their litters were bled at 7 and 14 d postpartum. Serum was analyzed for its Se concentration and glutathione peroxidase (GSH-Px) activity. Colostrum was collected within 12 h postpartum and milk at 7 and 14 d of lactation. When the basal diet was fed, sow serum GSH-Px activity declined from 6 d prepartum and remained low throughout lactation. When dietary Se levels increased, sow serum Se concentration and serum GSH-Px activity increased (P < .05) at both 7 and 14 d postpartum. The short-term feeding of either Se source at .15 or .30 ppm Se did not affect colostrum Se content when inorganic Se was fed, but it was increased when organic Se was provided. This resulted in a significant Se source x Se level interaction (P < .01). Milk Se at 7 and 14 d postpartum was 2.5 to 3 times higher when the organic Se source was provided and resulted in a significant Se source x Se level interaction (P < .05). When the combination of inorganic and organic Se was fed at .15 ppm Se, colostrum and milk Se contents were similar to those of sows fed .15 ppm Se from the organic Se source. Pig serum GSH-Px activity was not affected at 7 and 14 d of age by dietary Se level or Se source fed to the sow, but serum Se increased (P < .05) as dietary Se level increased, particularly when sows had been fed organic Se. The results demonstrated that organic Se increased milk Se content more than did inorganic Se and increased the nursing pig's serum Se. These results indicate that inorganic Se was more biologically available for sow serum GSH-Px activity, but organic Se was more effectively incorporated into milk.     

Efficacy of dietary sodium selenite and calcium selenite provided in the diet at approved, marginally toxic, and toxic levels to growing swine.

A 2 x 3 factorial experiment conducted in three replicates of a randomized complete block design compared the effects of calcium selenite and sodium selenite at three different levels of Se (.3, 5, or 15 ppm) in the diets of growing swine on performance and tissue Se concentrations. Ninety pigs averaging 12.5 kg of BW were given ad libitum access to corn-soybean meal diets fortified with one of the treatment Se sources and dietary levels for a 35-d experimental period. Growth and feed intake were similar in pigs fed .3 and 5 ppm of Se but were lower (P less than .01) in those fed 15 ppm from either Se source. Serum Se increased (P less than .01) as dietary Se level increased with no difference between Se sources at each dietary Se level. Liver, kidney, and longissimus muscle Se concentrations increased (P less than .01) as the dietary level of Se increased and were similar when either Se sources was provided. These results indicate that calcium selenite was as effective as sodium selenite using the measurement criteria of growth, serum, and tissue Se concentrations and glutathione peroxidase activities of growing swine when fed at approved, marginally toxic, and toxic dietary Se levels.     

Effect of dietary calcium on selenium retention in postweaning swine

Two experiments were conducted to evaluate the effect of dietary Se and Ca on Se utilization in postweaning swine. Two levels of dietary Se (.3 or 5.0 ppm) supplemented as sodium selenite and four levels of total dietary Ca (.50, .80, 1.10 or 1.40%) in a 20% protein, corn-soybean meal diet were evaluated. Inorganic Ca was supplied from dicalcium phosphate and limestone. In Exp. I, 135 pigs weaned at 4 wk of age were allotted by sex, litter and weight and fed a basal diet for 7 d and then their treatment diets for a 28-d period. Plasma and tissue were collected at the end of the trial for Se concentration and glutathione peroxidase (GSH-Px) activity. Dietary Ca had no effect on gain or feed measurements but 5.0 ppm Se depressed daily gain slightly. When 5.0 ppm dietary Se was fed, there resulted higher liver, kidney, heart and longissimus muscle Se concentrations than when .3 ppm was provided, but dietary Ca had no effect on tissue Se values within each dietary Se level. Plasma GSH-Px increased when higher dietary Se was provided, whereas neither heart nor liver GSH-Px activity was affected by dietary Se or Ca level. In Exp. II, a 5-d balance trial was conducted with 32 barrows after adjustment to their treatment diet for a 28-d period. Selenium retention increased quadratically as dietary Ca increased, whereas Ca retention was not affected by dietary Se. These results suggest that low dietary Ca levels may reduce total Se retention but not Se metabolism within body tissue.