亚硒酸钠、酵母硒和富硒螺旋藻对杂交鲟幼鱼生长、抗氧化能力及组织硒含量的影响

实验旨在研究饲料中不同类型和水平的硒源对杂交鲟(Acipenser baerii♂×Acipenser schrenckii♀)幼鱼生长、抗氧化能力及组织硒含量的影响。不同类型的硒源为亚硒酸钠、酵母硒和富硒螺旋藻,添加水平为0、0.4和1.2 mg/kg,制作对照饲料(C)、亚硒酸钠添加饲料(S1和S2)、酵母硒添加饲料(Y1和Y2)和富硒螺旋藻添加饲料(P1和P2)。使用实验饲料饲喂初始体重为(7.82±0.12) g的杂交鲟幼鱼,养殖62d。结果表明,不同硒源和硒水平对杂交鲟幼鱼的特定生长率和饲料效率无显著影响(P>0.05)。高水平亚硒酸钠显著提高了全鱼和肝脏硒含量(P<0.05),但对肌肉和脊椎骨硒含量无显著影响(P>0.05)。高水平酵母硒和富硒藻螺旋添加组杂交鲟幼鱼的全鱼、肝脏、肌肉及脊椎骨硒含量均显著高于对照组(P<0.05)。酵母硒添加组的血浆总蛋白(TP)和总胆固醇(TC)含量均显著高于对照组(P<0.05)。同时,高水平硒添加组杂交鲟幼鱼的血浆谷胱甘肽过氧化物酶(GSH-Px)活性显著高于对照组和低水平硒添加组(P<0.05)。亚...     

饲料中添加辅酶Q10对吉富罗非鱼幼鱼生长、抗氧化能力和组织结构的影响

以含辅酶Q10(CoQ10)分别为0、40、80和120 mg/kg的4种饲料饲喂平均初始体重为(19.97±0.13) g的吉富罗非鱼(Oreochromis niloticus, GIFT)幼鱼56d,探讨辅酶Q10对吉富罗非鱼幼鱼生长性能、体成分、抗氧化能力、组织结构和基因表达的影响。结果显示,各辅酶Q10组吉富罗非鱼幼鱼的终末体重、摄食率、特定生长率和饲料效率与对照组均无显著差异, 120 mg/kg辅酶Q10组终末体重、特定生长率和饲料效率均为最高;辅酶Q10含量为120 mg/kg时,吉富罗非鱼幼鱼的干物质消化率显著升高;各辅酶Q10组血清过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)活性均显著高于对照组;各辅酶Q10组肝脏CAT和GSH-Px活性均显著高于对照组, 80和120 mg/kg辅酶Q10组肝脏总超氧化物歧化酶(SOD)和谷胱甘肽S转移酶(GST)活性均显著升高,丙二醛(MDA)含量显著降低;各实验组去内脏全鱼的水分、粗蛋白和灰分含量均无显著性差异, 120 mg/kg辅酶Q10组去内脏全鱼粗脂肪显著低于对照组;各实验组内脏团水分、粗蛋白、粗脂肪和灰分...     

饲料中添加谷胱甘肽对黄颡鱼幼鱼组织谷胱甘肽含量、免疫及抗氧化性能的影响

研究旨在探讨饲料中添加还原型谷胱甘肽(Glutathione, GSH)对黄颡鱼幼鱼(Pelteobagrus fulvidraco)组织谷胱甘肽含量、免疫及抗氧化性能的影响。选用初始体重为(1.32±0.01) g的黄颡鱼800尾, 随机分为5组, 每组4个重复, 每个重复40 尾鱼, 分别投喂基础饲料和添加100、300、500和700 mg/kg GSH的试验饲料, 饲养56d后采样分析, 并采用氯化铵进行96h氨氮应激试验。结果表明: 除100 mg/kg组外, 饲料中添加GSH显著提高黄颡鱼肝脏、血清GSH含量(P<0.05), 当GSH添加量≥300 mg/kg时, 肝脏和血清GSH含量均呈现稳定状态。随着饲料中谷胱甘肽水平的增加, 血清免疫和肝脏抗氧化指标均呈现先升高后降低的趋势, 其中300和500 mg/kg组溶菌酶与碱性磷酸酶活性、300 mg/kg组免疫球蛋白M与补体4含量、500 mg/kg组酸性磷酸酶活性与对照组相比显著升高(P<0.05)。与对照组和700 mg/kg组相比, 300 mg/kg组肝脏超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化酶活性和总抗氧化能力与血清超氧化物歧化酶、谷胱甘肽过氧化酶活性均显著高升高(P<0.05); 且300 mg/kg组血清丙二醛含量显著降低(P<0.05)。氨氮应激96h时, 与对照组相比, 300 mg/kg组肝脏和血清超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化酶活性力均显著升高(P<0.05), 且300 mg/kg组血清丙二醛含量显著降低(P<0.05)。由此可见, 饲料中添加谷胱甘肽能提高黄颡鱼幼鱼组织谷胱甘肽含量、免疫及抗氧化性能, 其中以300—500 mg/kg为宜。     

团头鲂幼鱼吡哆醇适宜需求量的研究

试验采用单因素试验设计, 以饲料中吡哆醇浓度为影响因素, 研究了团头鲂幼鱼的适宜吡哆醇需求量。试验共配置了7组等氮等能的半纯化饲料, 其吡哆醇的实际含量分别为0、1.04、1.99、4.07、5.91、7.96和9.22 mg/kg。选用840尾均重:(6.810.17) g团头鲂幼鱼, 随机分为7组, 每组4重复, 每重复30尾鱼, 日投饵3次, 养殖期为8周。结果表明, 当饲料中吡哆醇含量由0升高至5.91 mg/kg时, 团头鲂的增重率、特定生长率、饲料利用率、成活率、蛋白效率比和氮保留率均得到显著改善(P0.05); 当吡哆醇含量进一步升高至9.22 mg/kg时, 蛋白效率比和氮保留率均显著下降(P0.05), 而其他指标则无显著变化(P0.05)。饲料中的吡哆醇含量显著影响团头鲂的肝体比(P0.05)且以5.91 mg/kg组为最低, 但对肥满度和胴体率均无显著影响(P0.05)。当饲料吡哆醇含量由0升高至5.91 mg/kg时, 肝脏谷草转氨酶和谷丙转氨酶活性以及吡哆醇含量均显著升高(P0.05); 当吡哆醇含量进一步升高至9.22 mg/kg时, 三者均无显著变化(P0.05)。以肝脏中的谷丙和谷草转氨酶活性以及吡哆醇含量为评价指标, 拟合折线模型得到团头鲂幼鱼的适宜吡哆醇的需求量为4.175.02 mg/kg。       

富硒壶瓶碎米荠对青鱼幼鱼生长、生理生化、硒代谢、抗氧化及先天免疫的影响

为探究富硒壶瓶碎米荠(Cardamine hupingshanensis)对青鱼(Mylopharyngodon piceus)幼鱼生长、血清生理生化、肝脏硒代谢、抗氧化能力和先天免疫指标的影响,选取360尾初始体重为(5.51±0.02) g的青鱼幼鱼随机分配至4个实验组中,每组3个重复。在基础饲料中添加富硒壶瓶碎米荠的量为0、0.5、1.0和2.0 g/kg(硒的实际含量分别为0.04、0.43、0.75和1.57 mg/kg),同时添加矿物质混合物(无硒添加)和维生素混合物,配置成4种等氮等能的青鱼幼鱼试验饲料,养殖周期为60d。结果显示:饲料中添加0.5和1.0 g/kg富硒壶瓶碎米荠时,鱼体增重率(WG),特定生长率(SGR)较对照组和过量组(2.0 g/kg)显著升高,饲料系数(FCR)显著降低(P<0.05)。当饲料中富硒壶瓶碎米荠添加量为0.5—1.0 g/kg时,血清中的甘油三酯(TG)、总胆固醇(TCH)和白蛋白(ALB)含量呈上升趋势,而葡萄糖(GLU)含量显著下降(P<0.05)。饲料中添加0.5—1.0 g/kg富硒壶瓶碎米荠时可显著提高肝脏核因子...     

饲喂不同浓度黄曲霉毒素B1饲料对花鳗鲡幼鱼生长、抗氧化能力和毒素积累的影响

以含不同浓度黄曲霉毒素B₁(AFB₁) (0、10、100和1000 μg/kg饲料)的4种饲料饲喂平均初始体重为(6.41±0.10) g的花鳗鲡(Anguilla marmorata)幼鱼56d, 探讨AFB₁对花鳗鲡幼鱼生长性能、抗氧化能力、肝脏组织结构及鱼体肌肉中的毒素积累的影响。结果表明, 各实验组幼鱼均未表现出行为及体色的异常。1000 μg/kg毒素组幼鱼的存活率、终末体重、摄食率、特定生长率和饲料效率显著低于对照组, 10 μg/kg毒素组和100 μg/kg毒素组与对照组无显著差异。10 μg/kg毒素组幼鱼肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)、谷胱甘肽S转移酶(GST)活性和丙二醛(MDA)含量与对照组无显著差异。饲料AFB₁含量≥100 μg/kg显著影响花鳗鲡幼鱼肝脏的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和谷胱甘肽转移酶(GST)活性。对照组和10 μg/kg毒素组幼鱼肝脏组织学观察未发现明显病理变化。1000 μg/kg毒素组幼鱼的肝脏细胞表现出严重的空泡化。随着饲料AFB₁水平的升高, 幼鱼肝脏和肌肉中AFB₁积累量均显著升高。1000 μg/kg毒素组幼鱼肝脏和肌肉中AFB₁积累量分别为17.75和5.98 μg/kg, 均超过FDA食品安全限定标准(5 μg/kg)。由此可见, 饲料中AFB₁≤10 μg/kg对花鳗鲡幼鱼是相对安全的浓度。     

美洲鳗鲡幼鱼饲料中鱼油的适宜添加水平研究

为研究饲料中鱼油添加水平对美洲鳗鲡(Anguilla rostrata)幼鱼生长性能、消化酶、体成分及肝脏脂肪代谢的影响, 以确定美洲鳗鲡幼鱼饲料中鱼油的适宜添加水平, 选用初始体重(8.34±0.12) g的美洲鳗鲡幼鱼800尾, 随机分成5组, 每组4个重复, 每个重复40尾; 分别投喂添加0(对照组)、3%(FO3组)、6%(FO6组)、9%(FO9组)和12%(FO12组)鱼油的试验饲料, 试验期56d。结果表明, 饲料中添加鱼油显著影响美洲鳗鲡幼鱼生长性能, FO6组美洲鳗鲡幼鱼的增重率、投饵率和饲料效率显著高于其他处理组(P<0.05)。与对照组相比, 鱼油添加组美洲鳗鲡幼鱼肠道脂肪酶活性显著提高(P<0.05), 蛋白酶和淀粉酶活性显著降低(P<0.05); FO6组、FO9组和FO12组全鱼粗脂肪含量显著提高(P<0.05), 全鱼粗蛋白质含量在FO12组显著降低(P<0.05), 全鱼水分和灰分含量无显著变化(P>0.05); FO9组和FO12组脂肪酸合成酶活性显著降低(P<0.05), FO12组脂蛋白酯酶和肝脂酶活性显著升高(P<0.05)。综上, 饲料中添加适宜鱼油水平可以提高美洲鳗鲡幼鱼的生长性能, 调节肠道脂肪酶活性、全鱼粗脂肪含量和肝脏脂肪代谢酶水平或活性; 美洲鳗鲡幼鱼获得最佳增重率和饲料效率时, 饲料中鱼油添加水平推荐为6.43%—6.78%。     

维生素E对青鱼幼鱼生长、免疫及抗氨氮胁迫能力的影响

以初始体质量(7.270.40) g的青鱼为研究对象, 采用维生素E(VE)有效含量分别为14.36(对照组)、25.14、37.66、62.97、113.92和210.45 mg/kg 6种等氮等能的实验饲料, 饲养青鱼幼鱼8周后, 根据生长情况选取对照组、62.97和210.45 mg/kg VE组进行24h氨氮胁迫(20 mg/L), 研究VE对青鱼幼鱼生长、免疫及抗氨氮胁迫能力的影响。结果表明: 以特定生长率为指标, 折线模型分析表明青鱼有效维生素E需要量为45.00 mg/kg。肌肉、肝脏和血清VE含量与饲料中VE含量呈明显正相关, 当饲料VE含量超过113.92 mg/kg时, 肌肉和肝脏VE含量均达到饱和。VE对鳃丝Na+/K+-ATP酶活性(NKA)和血清皮质醇(COR)无显著影响, 但随着饲料VE含量的升高, 过氧化氢酶(CAT)和总超氧化物歧化酶活性(T-SOD)呈上升趋势, 丙二醛含量(MDA)呈下降趋势。氨氮胁迫对各处理组肌肉VE含量和血清CAT活性无影响, 但肝脏VE含量均显著降低(P0.05), 且62.97和210.4 5 mg/kg VE组血清VE水平有所升高。在胁迫后, 对照组血清T-SOD、鳃丝NKA活性显著降低, 皮质醇含量显著增加(P0.05)。与对照组相比, 62.97和210.45 mg/kg VE组T-SOD、NKA活性和皮质醇含量在胁迫前后无显著变化。各处理组MDA含量在胁迫后虽均显著升高, 但210.45 mg/kg VE组在胁迫后MDA含量仍显著低于对照组(P0.05)。以上结果说明, 青鱼幼鱼获得最大生长的有效维生素E需求量为45.00 mg/kg, 且较高VE能有效提高青鱼机体免疫力, 缓解氨氮胁迫对青鱼机体的负面影响。       

VE和L-肌肽对大菱鲆幼鱼生长、抗氧化、非特异性免疫及血清生化指标的影响

实验以大菱鲆（Scophthalmus maximus）幼鱼[（14.00±0.02）g]为研究对象,采用2×4双因素设计,设2个VE水平（0和75 mg/kg）和4个L-肌肽水平（0、50、100和200 mg/kg）,研究VE和L-肌肽对其生长、抗氧化、非特异性免疫及血清生化指标的影响。实验共分8组,每组3个重复,每个重复46尾鱼,实验周期为8周。结果显示:（1）在饲料中添加75 mg/kg VE显著提高了大菱鲆幼鱼增重率（WGR）和特定生长率（SGR）（P < 0.05）,L-肌肽添加量≤100 mg/kg对实验鱼生长性能无显著影响（P>0.05）,添加量为200 mg/kg时鱼体WGR、SGR和蛋白质效率（PER）显著降低,饲料系数（FCR）显著升高（P < 0.05）;（2）VE和L-肌肽对血清谷胱甘肽过氧化物酶（GSH-PX）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量及肝脏总抗氧化能力（T-AOC）、超氧化物歧化酶（SOD）活性和MDA含量均具有显著的交互作用（P < 0.05）,在VE 75 mg/kg水平下,L-肌肽添加量为50和100 mg/kg时血清GSH-PX活性最高,L-肌肽添加量为100和200 mg/kg时血清CAT活性最高且与添加量为50 mg/kg差异不显著（P>0.05）,添加100 mg/kg肝脏T-AOC和SOD活性达到最高且50 mg/kg组的SOD与100 mg/kg组差异不显著（P>0.05）,主效应结果显示,VE显著提高了血清T-AOC、SOD及肝脏CAT活性（P < 0.05）,L-肌肽显著提高了血清T-AOC（P < 0.05）;（3）VE和L-肌肽对血清补体C3和LZM活性交互作用显著,在75 mg/kg VE水平下,L-肌肽添加量为50 mg/kg时,补体C3水平最高（P < 0.05）,主效应显示,VE和L-肌肽对血清总蛋白（TP）影响均不显著（P>0.05）;（4）添加VE显著降低了血清总胆固醇（TCHO）和甘油三酯（TG）含量（P < 0.05）,添加L-肌肽显著降低了血清TG含量,且在L-肌肽50 mg/kg时达到最低。综合考虑大菱鲆幼鱼[（14.00-39.43）g]的生长性能、抗氧化性能、非特异性免疫及血清生化指标得出,在实验配方条件下（鱼油70 g/kg,大豆卵磷脂10 g/kg）,添加VE 75 mg/kg时,L-肌肽的适宜添加量为50 mg/kg。     

硒和维生素E对皱纹盘鲍血清抗氧化酶活力的影响

利用双因素实验设计研究了在饲料中添加维生素E(VE) (0 ,5 0IU/kg)和硒 (Se) (0 ,0 2 ,0 6 ,1 5mg/kg)对皱纹盘鲍 (HaliotisdiscushannaiIno)血清中过氧化氢酶 (CAT)、超氧化物歧化酶 (SOD)、依赖硒的谷胱甘肽过氧化物酶(GPX)、谷胱甘肽还原酶 (GR)、谷胱甘肽转移酶 (GST)这 5种抗氧化酶活力的影响。结果表明 :Se对皱纹盘鲍血清 5种抗氧化酶活力都有显著影响 (P <0 0 5 ) ,而VE仅对GPX和GR的活力有显著影响 (P <0 0 5 )。VE和Se对CAT、GRX和GR的活力的影响具有显著的交互作用。GPX/SOD、GR/GPX、CAT/SOD这 3个抗氧化的重要指标都表明 ,当饲料中含有 4 5 0IU/kg的VE时 ,添加 0 6mg/kg的硒能使皱纹盘鲍血清中的抗氧化物酶系统总体达到相对平衡 ,从而能有效地抵抗氧化损害。     

A high-selenium diet induces insulin resistance in gestating rats and their offspring

Although supranutrition of selenium (Se) is considered a promising anti-cancer strategy, recent human studies have shown an intriguing association between high body Se status and diabetic risk. This study was done to determine if a prolonged high intake of dietary Se actually induced gestational diabetes in rat dams and insulin resistance in their offspring. Forty-five 67-day-old female Wistar rats (n=15/diet) were fed a Se-deficient (0.01 mg/kg) corn-soy basal diet (BD) or BD+Se (as Se-yeast) at 0.3 or 3.0mg/kg from 5 weeks before breeding to day 14 postpartum. Offspring (n=8/diet) of the 0.3 and 3.0mg Se/kg dams were fed with the same respective diet until age 112 days. Compared with the 0.3mg Se/kg diet, the 3.0mg/kg diet induced hyperinsulinemia (P<0.01), insulin resistance (P<0.01), and glucose intolerance (P<0.01) in the dams at late gestation and/or day 14 postpartum and in the offspring at age 112 days. These impairments concurred with decreased (P<0.05) mRNA and/or protein levels of six insulin signal proteins in liver and muscle of dams and/or pups. Dietary Se produced dose-dependent increases in Gpx1 mRNA or GPX1 activity in pancreas, liver, and erythrocytes of dams. The 3.0mg Se/kg diet decreased Selh (P<0.01), Sepp1 (P=0.06), and Sepw1 (P<0.01), but increased Sels (P<0.05) mRNA levels in the liver of the offspring, compared with the 0.3mg Se/kg diet. In conclusion, supranutrition of Se as a Se-enriched yeast in rats induced gestational diabetes and insulin resistance. Expression of six selenoprotein genes, in particular Gpx1, was linked to this metabolic disorder.     

Dietary selenium supplementation prolongs pentobarbital induced hypnosis

The present studies characterized the influence of dietary selenium (Na2SeO3) on the duration of pentobarbital (PB) induced hypnosis (sleep) in the rat. Rats were fed semipurified diets varying from 0.01 to 2.0 mg Se/kg for up to 4 weeks. Consumption of diets containing 1.0 and 2.0 mg Se/kg significantly prolonged PB induced hypnosis. Hepatic selenium, but not hepatic glutathione peroxidase activity, correlated with the length of PB induced hypnosis. The prolongation of hypnosis caused by diets containing 1.0 mg Se/kg was substantially reduced or eliminated by repeated exposure to PB. Although single exposure to increasing quantities of PB (60-100 mg/kg body weight) led to a progressive increase in sleep duration, the proportional increase caused by supplemental selenium (2.0 vs 0.1 microg Se/g) remained relatively constant (approximately 25%). Increasing maturity was inversely related to the duration of PB induced hypnosis, regardless of dietary selenium provided. Consumption of the 2.0 mg Se/kg diet prolonged PB induced hypnosis to a greater degree in immature than in mature rats (P < 0.05). Consumption of the selenium enriched diet (2 microg Se/g) resulted in an increase in cytochrome 2B, but had no effect on cytochrome 1A compared to controls (0.1 microg Se/g). Pretreatment of rats with P450 enzymes activators (i.e., PB, Aroclor 1254, or 3-methylcholanthrene) shortened the duration of PB induced sleep and masked the effects of dietary selenium. The current studies document that dietary selenium can influence the response to pentobarbital induced hypnosis and likely relates to changes in drug detoxification enzymes.     

The influence of dietary selenium and vitamin E on glutathione peroxidase and glutathione in the rat

The effect of dietary selenium (Se) and vitamin E supplementation on tissue reduced glutathione (GSH) and glutathione peroxidase activity has been studied in the rat. Increasing Se intake by 0.4 ppm gave significantly higher enzyme levels in all tissues studied, an effect not influenced by vitamin E intake. Further increasing Se to 4 ppm gave higher enzyme levels in red blood cells only, while in liver was there was a significant decrease in enzyme activity probably reflecting Se hepatotoxicity. In the absence of Se supplements increasing dietary vitamin E to 100 mg/kg diet significantly increased enzyme activity but this effect was modified by simultaneous Se supplementation.Se intake had no effect on GSH levels. Rats on high vitamin E intake 500 mg/kg had a significantly higher tissue GSH level. Dietary Se had a sparing effect on vitamin E, rats supplemented with Se having significantly raised plasma vitamin E levels.These results confirm the role of selenium in glutathione peroxidase and also show that vitamin E influences the activity of the enzyme.     

Effects of dietary selenium and vitamin E concentrations on phospholipid hydroperoxide glutathione peroxidase expression in reproductive tissues of pubertal maturing male rats

Phospholipid hydroperoxide glutathione peroxidase (PHGPX) is the second intracellular selenium (Se)-dependent glutathione peroxidase (GSH-Px) identified in mammals. Our objectives were to determine the effect of dietary vitamin E and Se levels on PHGPX activity expression in testis, epididymis, and seminal vesicles of pubertal maturing rats, and the relationship of PHGPX expression with testicular development and sperm quality. Forty Sprague-Dawley male weanling rats (21-d old), were initially fed for 3 wk a torula yeast basal diet (containing 0.05 mg Se/kg) supplemented with marginal levels of Se (0.1 mg/kg as Na₂SeO₃) and vitamin E (25 IU/kg as all-rac-α-tocopheryl acetate). Then, rats were fed the basal diets supplemented with 0 or 0.2 mg Se/kg and 0 or 100 IU vitamin E/kg diet during the 3-wk period of pubertal maturing. Compared with the Se-supplemented rats, those fed the Se-deficient diets retained 31, 88, 67, and 50% of Se-dependent GSH-Px activities in liver, testis, epididymis, and seminal vesicles, respectively. Testes and seminal vesicles had substantially higher (5-to 20-fold) PHGPX activity than liver. Dietary Se deficiency did not affect PHGPX activities in the reproductive tissues, but reduced PHGPX activity in liver by 28% (P < 0.0001). Dietary vitamin E supplementation did not affect PHGPX activity in liver, whereas it raised PHGPX activity in seminal vesicles by 43% (P < 0.005). Neither dietary vitamin E nor Se levels affected body weight gains, reproductive organ weights, or sperm counts and morphology. In conclusion, expression of PHGPX activity in testis and seminal vesicles was high and regulated by dietary Se and vitamin E differently from that in liver.     

Influence of a low-selenium diet on erythrocyte glutathione peroxidase and alkane production in exhaled air of rats as a measure of lipid peroxidation in vivo during growth

Erythrocyte glutathione peroxidase activity and alkane production in exhaled air of growing rats were studied as a measure of lipid peroxidation in vivo. When 4-weeks-old, rats were fed a low-selenium (0.05 mg/kg) refined soy concentrate-based diet but adequate in vitamin E and other nutrients. Rats of control groups were fed the same diet supplemented with varying amounts of selenium as sodium selenite. After 10 weeks, erythrocyte glutathione peroxidase activity in the group fed the low selenium diet had decreased to about 40% of the original level. Feeding this diet for a longer period resulted in a slow increase of the glutathione peroxidase level. After about 37 weeks, this level was equal to the initial level. During the same period of rapid growth, ethane and pentane production in the exhaled air of a group of similar animals on the diet containing 0.05 mg Se per kg was slightly although significantly higher compared with the levels of animals on a supplemented (0.4 mg Se per kg) diet. Differences were highest when glutathione peroxidase activity levels in the erythrocytes were lowest and negligible at the start of the experiment and after the period of rapid growth. These results support the view that the seleno-enzyme glutathione peroxidase is active in the defense mechanism of the cell against lipid proxidation.     

Influence of Different Amounts and Sources of Selenium Supplementation on Performance, Some Blood Parameters, and Nutrient Digestibility in Lambs

Two trials were conducted in a 2?×?2?+?1 factorial arrangement based on a completely randomized design to evaluate the effects of different sources of selenium (Se) on performance, blood metabolites, and nutrient digestibility in male lambs on a barley-based diet. The first trial lasted for 70 days and consisted of 30 lambs (35.6?±?2.6 kg mean body weight, about 4–5 months of age) which were randomly allotted to five treatments including: (1) basal diet (containing 0.06 mg Se/kg DM; control) without supplementary Se, (2) basal diet?+?0.20 mg/kg Se as sodium selenite (SeS 0.20), (3) basal diet?+?0.40 mg/kg Se as sodium selenite (SeS 0.40), (4) basal diet?+?0.20 mg/kg Se as selenium yeast (SeY 0.20), and (5) basal diet?+?0.40 mg/kg Se as selenium yeast (SeY 0.40). For the second trial, four lambs from each group of experiment 1 were randomly allocated to individual metabolic cages for 14 days to measure the effects of dietary Se on nutrient digestibility. The results revealed that there were no significant differences for average daily gain, average daily feed intake, feed/gain ratio, hematological parameters (packed cell volume, red blood cell, white blood cell, and hemoglobin values), serum total protein, albumin, globulin, aspartate amino transferase, alkaline phosphatase, and creatine phosphokinase due to supplementation of different amounts and sources of Se in lambs. Dietary Se supplementation significantly improved (P?<?0.001) glutathione peroxidase activity in blood. Furthermore, at the end of the trial, serum tri-iodothyronine (T3) amount also increased (P?<?0.05), while serum thyroxine (T4) amount decreased (P?<?0.05). Digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber increased (P?<?0.05) by Se yeast supplementation. It may be concluded that supplementation of Se in lambs had no significant effect on performance and blood hematology, but increased blood glutathione peroxidase activity and serum T3 amount and decreased serum T4 amount as compared to non-supplemented control lambs. Furthermore, Se yeast improved nutrient digestibility in lambs.     

大黄鱼稚鱼L-蛋氨酸需要量的研究

研究了1242日龄大黄鱼（Pseudosciaena crocea R.）稚鱼蛋氨酸需要量。以白鱼粉、磷虾粉和乌贼粉作蛋白源,通过添加L-晶体氨基酸使饲料与大黄鱼卵的必需氨基酸组成一致（蛋氨酸除外）,制成6种等氮（8.8%）等能（16.65 kJ/g）的微黏合饲料。L-蛋氨酸梯度依次为饲料的1.19%、1.62%、2.18%、2.65%、3.13%和3.66%,或饲料蛋白的2.17%、2.95%、3.95%、4.81%、5.70%和6.65%。以生物饵料（丰年虫无节幼体和桡足类）作对照组。每处理设3个重复,每桶（180 L）内随机放3500尾初始体重为（1.930.11） mg 的12日龄大黄鱼稚鱼。实验为期30d。结果显示,稚鱼的成活率随饲料蛋氨酸水平的升高而升高,在2.18%蛋氨酸水平时达到最高,之后无显著变化。特定生长率（SGR）随饲料蛋氨酸水平的升高而升高,在2.18%蛋氨酸水平时达到最高,之后则呈下降趋势。对照组稚鱼的成活率和SGR最高,均显著高于蛋氨酸组（P0.05）。各组间稚鱼体脂肪和灰分差异不显著,但体蛋白随饲料蛋氨酸水平的升高而升高,在2.65%蛋氨酸水平时达到最高,之后则稍微下降;对照组鱼体蛋白和各必需氨基酸含量均显著高于其他组（P0.05）。经二次多项式模型分析,1242日龄大黄鱼稚鱼的蛋氨酸需要量为饲料的2.58%或饲料蛋白的4.69%。       

Glutathione Peroxidase Activity and Erythrocyte Lipid Peroxidation as Indices of Selenium and Vitamin E Status in Young Pigs

A randomized, blocked 23 factorial experiment was conducted with 48 pigs from sows fed a diet low in selenium and vitamin E. From 3 to 12 weeks of age the piglets were kept in single pens and fed a basic diet consisting mostly of barley, dried skim milk, soybean meal and dried yeast, and containing 55 µg selenium and 3 mg vitamin E per kg. The treatment factors — i.e. feed supplements — were 2 levels of Se (nil, 60 µg/kg), 2 levels of vitamin E (nil, 50 mg/kg), and 2 levels of the feed antioxidant ethoxyquin (nil, 150 mg/kg). Blood samples, collected at termination of the experiment, were examined for glutathione peroxidase activity (GSH-Px) and resistance against erythrocyte lipid peroxidation (ELP) to evaluate Se and vitamin E status, respectively. Analysis of variance showed the GSH-Px activity to be litter-dependent (P < 0.001) and influenced by selenium supplementation (P < 0.001) but not by the other supplements or by interactions between supplements. Resistance against ELP was influenced only by vitamin E supplementation (P < 0.001). GSH-Px and ELP thus seem to be valuable and simple methods for evaluating, respectively, Se status and vitamin E status in growing pigs.