微量元素硒的营养功能

硒的原子序数为34，具有非金属性和金属性。单质硒有三种同素异性体：无定性硒、晶体硒和金属硒。化合态的硒有低分子量化合物和高分子量化合物存在于生物体内。低分子量化合物如硒代半胱氨酸、硒代胱氨酸、胆汁硒、硒代牛黄酸、硒代辅酶A,此外还有亚硒酸钠(含硒45.7％)、硒酸钠(含硒41.8％)、硒化钠(含硒63．2％)、亚硒酸钙(含硒47．3％)。高分子量化合物有谷胱甘肽过氧化物酶(GSH-PX)、甲酸脱氢酶、甘氨酸还原酶、烟酸羟化酶、黄嘌呤脱氢酶、硫解酶以及各种含硒的蛋白质，例如硒蛋白P。     

微量元素硒的营养功能

1硒的理化性质硒的原子序数为34,具有非金属性和金属性。单质硒有三种同素异性体:无定性硒、晶体硒和金属硒。化合态的硒有低分子量化合物和高分子量化合物存在于生物体内。低分子量化合物如硒代半胱氨酸、硒代胱氨酸、胆汁硒、硒代牛黄酸、硒代辅酶A,此外还有亚硒酸钠(含硒45.7%)、硒酸钠(含硒41.8%)、硒化钠(含硒63.2%)、亚硒酸钙(含硒47.3%)。高分子量化合物有谷胱甘肽过氧化物酶(GSH-PX)、甲酸脱氢酶、甘氨酸还原酶、烟酸羟化酶、黄嘌呤脱氢酶、硫解酶以及各种含硒的蛋白质,例如硒蛋白P。动物体含硒约0.05～0.2m g/kg,肌肉中总硒含量…     

微量元素硒的生物学功能简介

硒是动物生长发育所必需的元素,这是1973年联合国卫生组织正式宣布的。1动物体内硒的存在情况 动物机体内硒含量一般为每千克体重20-25微克。机体所有组织和细胞均含硒,但在各组织中的分布不同。据报道,在综合对比分析绵羊各组织硒含量后认为机体硒含量与日粮硒含量有明显的线性关系,在日粮正常硒含量条件下,机体组织硒含量按肾、肝、胰、脾、心、骨、肌肉、脂肪为顺序依次递减。硒以低分子量化合物如无机硒（亚硒酸钠、硒酸钠、硒化钠、亚硒酸钙等）,有机硒,酵母硒,以及高分子量化合物如谷胱甘肽过氧化物酶,甲酸脱氢酶,甘氨酸还原酶以及各种含硒的蛋白质等存在于生物体内。     

复方亚硒酸钠在畜牧兽医中使用效果经验谈

亚硒酸钠应用到畜牧生产已有几十年的历史,近几年来复方亚硒酸钠(VE亚硒酸钠)在畜牧生产中更加广泛使用,给畜牧业经济带来了较大的效益.复方亚硒酸钠在畜牧兽医中应用主要表现在以下几方面:     

三硫钼酸钠对大鼠镉代谢的影响

补饲三硫钼酸钠,可以减少镉在生命器官内沉着,促进镉从粪、尿中排泄。在镉污染期,日粮中补饲硫钼酸钠,可使粪便镉排泄增多12.95％～33.66％,尿液镉排泄增多7.56％～21.66％,短期试验中显示增加更多。在粪中镉增多同时,钼浓度也增多,两者间呈正相关系（r=0.9596）。当停止镉污染以后,日粮中继续补饲I7ppm、10ppm、5ppm Mo的三硫钼酸钠,可使粪便镉排泄分别增加65.72％、10.18％和22.33％,尿液镉排泄分别增加109.17％、34.20％和50.36％,与未补钼的镉中毒大鼠相比,差异非常显著（P<0.01)。硫钼酸盐促进镉排泄的机理与它可使MT-Cd解离,使Cd转入分子量较大的蛋白质,因而有利于镉排泄有关。     

亚硒酸钠对游离脂肪酸致肝细胞凋亡和线粒体膜电位降低的保护作用

为研究亚硒酸钠对游离脂肪酸 (free fatty acid,FFA) 致体外培养大鼠肝细胞凋亡和线粒体膜电位降低的保护作用,本试验通过胶原酶两步灌流法分离培养肝细胞,在细胞培养液中添加FFA和亚硒酸钠 (0.1 μmol/L)测定细胞的凋亡情况、细胞功能和线粒体膜电位。结果表明,随着培养液中FFA浓度的升高,细胞凋亡加重,肝细胞功能受到影响,线粒体膜电位降低且FFA的这种作用呈剂量依赖性;亚硒酸钠能抑制由FFA引起的肝细胞的上述变化。     

滴定法测定亚硒酸钠维生素E预混剂中亚硒酸钠的含量

采用硫代硫酸钠滴定液(0.01mol/L)滴定,测定该预混剂中亚硒酸钠含量。结果表明,在8.0～12.7mg范围内,滴定亚硒酸钠的取用量与消耗的硫代硫酸钠滴定液体积呈良好的线性关系,其线性回归方程:Vi=2.3918×Mi-0.2878,r(相关系数)=0.9998,方法的平均回收率为99.5%,相对标准偏差(RSD)为0.8%。本法操作简便,结果准确,适合于亚硒酸钠维生素E预混剂中亚硒酸钠含量测定的质量控制。     

微量元素硒在养猪生产中的应用

<正>硒(Selenium,Se)是动物必需的微量元素之一。硒在地壳中含量极低,而且分布很不均匀,动物的白肌病、桑葚心病、营养性肝坏死等疾病均与缺硒有关。饲料原料中的鱼粉含硒较高,苜蓿粉、黑麦等次之,饼粕较少,谷类最低。硒以无机硒和有机硒2种形式存在,无机硒包括亚硒酸钠、硒酸钠、硒化钠、亚硒酸钙等;有机硒包括硒酵母、硒代蛋氨酸、硒代胱氨酸、海藻硒多糖等,猪对有机硒的生物利用率高于无机硒。1硒的抗氧化作用硒在体内的生物学作用有很多种,     

羧甲基壳聚糖硒对小鼠脏器指数、脾脏空斑形成细胞溶血能力及血浆SOD活性的影响

为研究羧甲基壳聚糖硒对小鼠脏器指数、脾脏空斑形成细胞溶血能力及血浆超氧化物歧化酶(SOD)活性的影响,试验选择KM小鼠60只(雌雄各半)随机分为对照组、亚硒酸钠组和羧甲基壳聚糖硒组,每组20只(雌雄各半)。对照组饲喂基础日粮,亚硒酸钠组和羧甲基壳聚糖硒组分别在基础日粮中添加亚硒酸钠和羧甲基壳聚糖硒(其剂量以硒计均为0.2 mg/kg),试验期28 d。结果表明:羧甲基壳聚糖硒组小鼠脾脏空斑形成细胞溶血能力高于亚硒酸钠组,亚硒酸钠组高于对照组,且差异极显著(P0.01);羧甲基壳聚糖硒组小鼠血浆SOD活性高于亚硒酸钠组,亚硒酸钠组小鼠血浆SOD活性高于对照组,且羧甲基壳聚糖硒组与亚硒酸钠组之间无显著差异(P0.05),亚硒酸钠组与对照组之间差异显著(P0.05);羧甲基壳聚糖硒组与亚硒酸钠组和对照组小鼠的肝脏、肾脏、心脏和脾脏指数相比均有所增加,亚硒酸钠组与对照组相比有所下降,但差异不显著(P0.05)。说明羧甲基壳聚糖硒与亚硒酸钠均能显著增加小鼠的脾脏空斑形成细胞溶血能力和血浆SOD的活性,但对小鼠的脏器指数无影响。     

鸡补硒过量的防治方法

正1)预防。坚持微量间断补硒是防止鸡补硒过量引起硒中毒的有效方法。给鸡补硒的方法如下。(1)注射0.005%的亚硒酸钠溶液(0.1%亚硒酸钠1 mL加19 mL灭菌水)1 mL/只,1次注射即可。(2)在鸡1~3日龄、20~23日龄、40~43日龄时以1~2 mg/L的亚硒酸钠溶液饮水或拌料内服,连续饲喂3 d,可预防鸡缺硒症。如果同时在饲料中添加足量的维生素E、含硫氨基酸、抗氧化剂等,则补硒效果更好。     

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。     

Effect of selenate as a feed supplement to dairy cows in comparison to selenite and selenium yeast

The main aim of this trial was to define the possible differences between selenite and selenate in their ability to increase the selenium (Se) concentration of milk, in comparison with organic Se. Dairy cows (n = 42) were fed a basal diet containing .10 to .12 mg Se/kg DM for 5 mo and were then divided into four groups of 10 or 11, as similar as possible in age and stage of lactation. During the next 84 d, the cows in three of the groups were supplemented with 3 mg of Se daily, whereas the cows in one control group remained unsupplemented. The Se supplement was given as sodium selenite, sodium selenate, or a Se yeast product. The total Se concentration of the diets varied with the cows' stage of lactation and was for the supplemented groups .24 to .31 mg/kg DM, but remained between .10 and .12 mg/kg in the control group. At the end of the trial, the mean whole blood Se concentrations in the selenite, selenate, yeast, and control groups were 138, 141, 165, and 104 microg/L, respectively. The Se concentration in plasma apparently reached a plateau level within 4 wk, at approximately 75 microg/L in the selenite group, 80 microg/L in the selenate group, and 90 microg/L in the yeast group. In the control group the mean concentration in plasma remained at approximately 50 microg/L. The increase of the activity of glutathione peroxidase (GSH-Px) in the erythrocytes was significantly higher in the supplemented groups than in the control group. The mean concentrations of Se in milk in the selenite, selenate, and yeast groups were 16.4, 16.4, and 31.2 microg/L, respectively, whereas the concentration remained at approximately 14 microg/L in the control group. The milk Se concentration reached a plateau within 1 wk after the start of Se supplementation. Dietary supplementation with selenite and selenate, thus, had only a limited effect on the Se concentration in milk, and there was no significant difference between the two inorganic compounds in any variable measured. Organic Se was much more effective than inorganic Se in increasing the concentration of Se in milk.     

Effects of a supranutritional dose of selenate compared with selenite on insulin sensitivity in type II diabetic dbdb mice

The present study was performed to examine the mechanism by which selenate ameliorates the insulin sensitivity in type II diabetic dbdb mice. Therefore, 21-adult female dbdb mice were randomly assigned to three experimental groups (0Se, SeIV and SeVI) with seven animals per group. Mice of group 0Se were fed with a selenium-deficient diet (<0.02 mg Se/kg) based on wheat and torula yeast for 8 weeks whereas the mice of groups SeIV (selenite) and SeVI (selenate) were fed with sodium selenite and sodium selenate (up to 35% of the LD(50) for mice in eighth week), in addition to the diet by daily tube feeding. Eight weeks of selenate application led to significantly elevated insulin sensitivity in comparison with selenium deficiency and selenite application. The activity of cytosolic protein tyrosine phosphatases (PTPs) as important negative regulators of insulin signalling was reduced from 53.8% to 22.5% in the liver and skeletal muscle of selenate-treated mice in comparison with the selenium deficient and selenite-treated controls, suggesting an inhibition of PTPs by intermediary selenate metabolites. In an additional in vitro inhibition study, selenate (oxidation state +VI) did not inhibit PTP activity. Selenium metabolites in the oxidation state +IV were found to be the actual inhibitors of PTP activity. In conclusion, the results of the present study show that one possible mechanism by which supranutritional selenate doses enhance insulin sensitivity in type II diabetic dbdb mice is based on the inhibition of PTPS as negative regulators of insulin signalling. Moreover the cellular metabolism of selenate including its intermediary reduction to the oxidation state +IV seems to play a crucial role during this process.     

Effect of Vitamin D 3 on Cadmium Retention by Laying Hens

The effect of cadmium (Cd) and vitamin D 3 on Cd retention in the organism of laying hens was observed. Hens ( n =48) were divided into eight groups with six animals per group as follows: experimental groups 1, 3 and 5 were administered Cd (0.3, 0.6 and 6.0 mg CdCl 2 kg -1 body weight, respectively) daily in water and groups 2, 4 and 6 were administered the same CdCl 2 concentrations supplemented with vitamin D 3 (100 IU hen -1 ). C1 was a control group without any supplements and C2 a control group supplemented only with vitamin D 3 . Samples of inner organs were analysed by atomic absorption spectrophotometry after 6 months of Cd exposure. A significant elevation in Cd levels, mainly in the liver and kidneys, was found. A significant decrease ( P h 0.01) in Cd levels in the liver was recorded after the addition of 6.0 mg CdCl 2 kg -1 body weight and vitamin D 3 , in comparison with the group without vitamin D 3 (18.76 vs. 10.33 mg kg -1 ). A similar decrease in Cd levels in the kidney ( P h 0.001) at the same supplementation dose of Cd was obtained in comparison with the group without vitamin D 3 (145.32 vs. 60.37 mg kg -1 ). The results confirmed that vitamin D 3 is able to reduce the Cd content in the organism of laying hens. The main effect of vitamin D 3 was demonstrated by decreasing Cd retention in the liver and especially in the kidneys.     

Dietary selenate versus selenite for cattle, sheep, and horses.

Food and Drug Administration regulations currently permit addition of .3 mg of Se per kilogram of diet for chickens, turkeys, ducks, swine, sheep, and cattle. However, field reports indicate that this level may not be adequate for ruminants in all situations. Because sodium selenite is the most common supplemental form and is known to be readily absorbed to particles or reduced to insoluble elemental Se or selenides in acid, anaerobic environments, studies were conducted with dairy cattle, sheep, and horses fed sodium selenate to determine whether Se from this source was more bioavailable than Se from sodium selenite. A 2-wk period of no Se supplementation was followed by 49 or 56 d of Se supplementation at .3 mg/kg of dietary DM. Serum Se concentrations and glutathione peroxidase (GSHPx) activities measured initially and periodically thereafter revealed no difference between Se forms in sheep and horses and only a small (P less than .05) advantage for selenate in supporting serum Se concentration in dairy cattle. Selenium concentrations in skeletal muscle and liver of sheep were not different between Se forms. Serum Se, but not GSHPx, increased with time, and .3 mg of supplemental Se per kilogram of dietary DM from either sodium selenate or sodium selenite supported normal serum Se concentrations in sheep, dairy cattle, and horses.     

硒对猪瘟疫苗强化作用的研究

用亚硒酸钠作猪瘟兔化弱毒疫苗的强化剂对体重１８￣２０ｋｇ的６０日龄仔猪进行免疫实验研究。结果表明，硒可使动物外周血液中的Ｂ淋巴细胞增数、血清免疫抗体水平提高，且出现时间较早、维持时间较长。本研究采用的硒剂量（ＮａＳｅＯ３０．１ｍｇ／ｋｇ体重）未见对动物实质器官的损害作用。对６１．８万头猪的推广试验结果表明，该方法确定可增强猪瘟疫苗的免疫效果。     

亚硒酸钠和酵母硒对蛋鸡生产性能、蛋硒含量、蛋品质的影响

本试验旨在研究酵母硒和亚硒酸钠作为硒源对产蛋高峰期蛋鸡生产性能、蛋硒含量、蛋品质以及储存期内蛋品质的影响。选用27周龄600只产蛋高峰期海兰褐蛋鸡,随机分为2个处理,每个处理3个重复,每个重复100只鸡。在日粮中分别添加0.2 mg/kg的亚硒酸钠和酵母硒(试验日粮实测硒含量分别为0.227、0.233 mg/kg),预试期1周,正试期8周,对鸡蛋28 d内的鸡蛋蛋品质进行跟踪检测。结果表明:酵母硒和亚硒酸钠对海兰褐蛋鸡生产性能的影响不显著;与亚硒酸钠组相比,酵母硒组对28 d鸡蛋蛋品质无显著影响,但可显著提高56d鸡蛋的蛋白高度和哈氏单位(P<0.05);与添加亚硒酸钠相比,添加酵母硒减缓了储存期鸡蛋哈氏单位的降低,有利于延长鸡蛋货架期;酵母硒组蛋黄、蛋清中硒含量显著高于亚硒酸钠组(P<0.05)。由此可见,相较于亚硒酸钠,饲喂含酵母硒的日粮在延长鸡蛋货架期、提高蛋黄和蛋清中的硒沉积方面效果更好。     

不同SDS电泳法对家蚕低分子Kunitz型抑制剂分子量鉴定的影响

采用15％SDS聚丙烯酰胺凝胶电泳和tricine—SDS聚丙烯酰胺凝胶电泳分剐对家蚕血液中低分子Kunitz型胰凝乳蛋白酶抑制剂CI-13的分子量进行了检测，SDS—PAGE结果为12．5kDa，而tricine SDS-PAGE结果为7．3kDa。另根据CI-13的氨基酸组成，算出分子量为7，113Da，这表明tricine SDS—PAGE的结果与氨基酸组成测定值接近，是适用于家蚕低分子Kunitz型抑制剂分子量鉴定的电泳方法。     

The Effect of Cysteine and Sodium Selenite on the Toxicity of Cadmium in Staphylococcus Aureus

Cysteine was shown to have a protective effect on the killing rate caused by cadmium (Cd) but no effect on the uptake of Cd in S. aureus 3719-. The addition of 254 × 10⁻³ mmol/l of sodium selenite or more into the liquid growth medium increased the lag phase of growth of S. aureus 3719-. Sodium selenite had no protective effect on the toxicity of Cd in S. aureus 3719- as evaluated by the length of the lag phase of growth in the presence of Cd and varying amounts of sodium selenite. 534 × 10⁻⁶ mmol/l of sodium selenite in the growth medium had no effect on the uptake of Cd in S. aureus.     

Chronic cadmium treatment induces islet B cell injury in ovariectomized cynomolgus monkeys

In an attempt to establish a primate model of chronic cadmium (Cd) toxicosis, we ovariectomized cynomolgus monkeys and treated with CdCl2 by repeated intravenous injections for 13 to 15 months. The animals showed an increase in blood glucose from Month 10 and a decrease in blood insulin at Month 11of the Cd-treatment. Histopathological examination of the Cd-treated animals revealed islet atrophy with reduction in islet number and vacuolation of the islet cells, whereas there was no remarkable change in the acinar cells of the exocrine pancreas. In histomorphometrical examination, insulin-positive areas in the islets were significantly decreased, accompanying a relative increase of glucagon-positive areas. Large amounts of Cd accumulated in the pancreas, and metallothionein (MT), a Cd binding protein, was localized in the islets of Cd-treated animals. The present study demonstrated that the chronic intravenous injection of Cd to cynomolgus monkeys induced the accumulation of the metal in the pancreas, degeneration of islet B cells and the diabetic clinical signs. Therefore the islet B cell is one of the major targets of the chronic Cd poisoning in monkeys.