The effects of dietary oxidized fat and selenium source on performance,glutathione peroxidase,and glutathione reductase activity in broiler chickens

Normal or elevated selenium status of broilers, which is influenced by dietary selenium sources, improves the bird’s ability to overcome the adverse effects of reactive oxygen metabolites. The objective of this study was to evaluate the effects of feeding graded levels of peroxidized poultry fat on blood and hepatic glutathione peroxidase (GSH-Px), and hepatic glutathione reductase activity in broiler chickens fed either inorganic sodium selenite (SEL) or organic selenium enriched in the organic selenium yeast product Sel-Plex (SP). Nine starter diets, varying in levels of oxidized fat (0, 3, and 6 mEq/kg) and dietary selenium sources, were fed to 360 male chicks from hatch to 21 d of age. Sel-Plex or SEL was added to the basal diet to provide either 0 or 0.2 ppm of supplemental selenium in the diets. Blood and hepatic samples were obtained for each treatment group at 21 d of age. Neither peroxidized fat nor selenium source significantly altered the activity of hepatic glutathione reductase (P ≤ 0.05). Blood GSH-Px was influenced significantly by both fat and selenium source (P ≤ 0.05), but the fat × selenium source interaction was not significant (P ≥ 0.3). A selenium source effect on the hepatic GSH-Px activity (P ≤ 0.05) was evidenced by higher GSH-Px activity, even in the basal diet with no added peroxidized fat. An increase in GSH-Px activity was seen in the erythrocyte and hepatic samples in both the SEL and SP treatments when peroxidized fat was given at 3 mEq/kg, but in the erythrocytes and in the hepatic tissues from SEL-supplemented birds, there was an apparent inhibition of GSH-Px activity. This inhibition was not seen in the hepatic tissue samples from SP-fed birds. Because elevated GSH-Px activity is indicative of oxidative stress, it was concluded that dietary SP supplementation resulted in better selenium and redox status in broilers than did SEL. These results indicate that the dietary selenium supplied in an organic form (selenium yeast as SP) improved the selenium and redox status in broilers, leading to greater resistance to oxidative stress than when the inorganic form of selenium (SEL) was fed.     

不同硒水平对生长育肥猪血液生化指标的影响

试验研究了宁夏常用饲料中不同硒水平对生长育肥猪血液生化指标的影响。结果表明 :(1 )谷胱甘肽过氧化物酶 (GSH PX)活性随饲粮硒水平的增加 ,呈现下降 上升 下降的动态变化趋势。谷胱甘肽硫转移酶可反映缺硒的程度。 (2 )缺硒组仔猪血硒含量和全血中GSH PX均处于缺硒边缘状态 ,在临界值以下 ,不能满足仔猪的代谢需要。 (3)随饲粮硒水平的逐渐增加 ,猪瘟的抗体水平和淋巴细胞转化率明显升高 ,以饲粮中添加硒 0 45mg/kg时达到最高 ,仔猪发病率最低     

Barium selenate as a slow-release selenium preparation to pigs

Pregnant sows were injected subcutaneously (s.c.) or intramuscularly (i.m.) with a barium selenate suspension (0.5–1.0 mg Se/kg body weight (b.w.)) and together with control animals fed a commercial diet. No response to the injection was seen either in blood selenium levels or in glutathione peroxidase (GSH-Px) activity in the sows. There was, however, a significant difference in these parameters between piglets born from treated dams and control animals. This status was maintained during the nursing period. In another experiment pigs (20 kg b.w.) on a Se-deficient diet were injected s.c. and i.m. with barium selenate (2.5 mg Se/kg b.w.). The treated groups maintained their blood levels of selenium and GSH-Px activity, although the selenium values in the group treated intramuscularly started to decline after 4 weeks. Organ samples from both groups were equal with regard to selenium at the time of slaughter while the control group showed a rapid decline both in blood selenium levels and GHS-Px activity.     

不同硒水平对猪和大鼠的生长性能、组织硒含量、血GSH-Px活性的影响及比较

采用仔猪36头和大鼠144只,在低硒玉米—豆饼基础日粮上,以亚硒酸钠形式添加0、0·02、0.1、0.5、2.5、12.5ppm的硒,分别测定了不同硒水平对猪、大鼠生长性能、组织硒含量和血GSH-Px活性的影响,并在此基础上对两者进行了比较。试验结果表明,高硒和低硒都能影响猪、大鼠的生长性能及各组织硒含量,大鼠的反应较敏感;猪、大鼠血GSH-Px活性的对数值在一定范围内均随饲料硒水平的增加而升高。因此认为,通过大鼠亦能迅速捕捉到猪体试验的某些结果,可作为猪模拟或预备性试验的较为敏感、经济的动物。     

Effect of selenium on performance, serum selenium concentration and glutathione peroxidase activity in pigs

Pigs from sows fed a diet deficient in Se and low in vitamin E were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Dietary treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Some death loss occurred in pigs receiving no supplemental Se at approximately 5 wk of age. Autopsy revealed liver and heart lesions typical of vitamin E-Se deficiency. Selenium supplement had no significant effect on average daily gain, feed intake or gain to feed ratio for the 4-wk experiment. Selenium status of pigs was determined by serum Se concentration and serum glutathione peroxidase (GSH-Px) activity. Serum Se increased linearly (P less than .01) with increasing supplemental Se. Serum GSH-Px activity increased linearly (P less than .01) and quadratically (P less than .05) with increasing supplemental Se. With time, the level of serum Se and GSH-Px activity decreased in unsupplemental pigs, but increased in pigs fed diets supplemented with Se and resulted in significant interactions (P less than .01) between dietary Se level and time on experiment. The correlation between serum Se concentration and GSH-Px activity was .81 (P less than .01).     

Clinico-Pathologic Findings in Young Pigs Fed Different Levels of Selenium,Vitamin E and Antioxidant

A randomized, blocked 2³ factorial experiment was conducted with 48 young pigs. The treatment factors were: 2 levels of selenium (55 and 115 µg/kg), 2 levels of vitamin E (3 and 53 mg/kg) and 2 levels of the antioxidant feed additive Ethoxyquin (0 and 150 mg/kg). All pigs were kept in single pens and fed ad libitum throughout the experimental period of 9 weeks, i.e. from 3 to 12 weeks of age.Plasma, heart, liver and muscle Se levels as well as whole blood glutathione peroxidase activity (EC 1.11.1.9 GSH-Px) were significantly higher in pigs given a dietary supplement of Se than in pigs given no supplement of Se (P ≤ 0.001). The Se-supplemented pigs showed a tendency to lower mean serum transaminase activity (ASAT and ALAT) than unsupplemented pigs, but the influence was significant (P ≤ 0.05) only for the ALAT activity.Blood vit. E levels were higher for pigs receiving a supplement of vit. E than for unsupplemented pigs (P ≤ 0.001), and so was the resistance of red blood cells against lipid peroxidation (ELP), as expressed by lower ELP values.There were no effects of Ethoxyquin supplementation on the biochemical variables included in the study.The histological examination of heart muscle showed that the score for changes was negatively influenced by both Se and vit. E supplement (P ≤ 0.001) and to some extent also by Ethoxyquin supplement (P ≤ 0.05). The histological picture of m. long dorsi was influenced only by the vit. E supplement (P ≤ 0.01). No histological changes were found in the liver in this study. There were inverse relationships between whole blood GSH-Px defluorescence time and blood Se, and between ELP and whole blood vit. E (P ≤ 0.001).     

Combined Therapeutic Effect of Dietary Selenium and Vitamin Ε on Manifested Vesd Syndrome in Weaned Pigs

By using a therapeutic dietary supplementation in pigs, which had developed the vitamin Ε and selenium deficiency (VESD) syndrome, the same amounts of α-tocopheryl acetate and selenium were found to be effective as under prophylactic conditions. The experiment thus supported the conclusions that the addition of 5 mg DL-α-tocopheryl acetate/kg and 135 μg selenium/kg to a diet, which contained only traces of vitamin Ε and selenium, represents a level of minimal requirement. Glutathione peroxidase activity in blood serum was used to evaluate the selenium status in pigs. A modified method for determination of tocopherol in fat tissue was described. The addition of 15 mg α-tocopheryl acetate/kg diet was demonstrated to be sufficient to maintain the tocopherol stores in body fat at an unchanged level.     

Selenium and glutathione peroxidase levels in lambs receiving feed supplemented with sodium selenite or selenomethionine

Twenty-one 6 months old female lambs were divided into 7 groups and fed a basal diet containing 0.13 mg Se/kg. The basal diet was further supplemented with 0, 0.1, 0.5 or 1.0 mg Se/kg either as sodium selenite or as selenomethionine, and was fed for 10 weeks. Both feed additives produced an increase in the selenium concentration in the tissues analysed. Significant correlations were found between the concentrations of selenomethionine or sodium selenite added to the feed and the subsequent tissue levels. However, the selenium levels seemed to plateau at approximately 0.5 mg Se/kg of supplemented sodium selenite. The total glutathione peroxidase (GSH-Px) activity of the tissues increased when the selenium supplementation increased from 0 to 0.1 mg/kg for both selenium compounds. With further increase in selenium supplementation the GSH-Px activity in the tissues plateaued except in the blood where the activity continued to rise with increasing selenomethionine supplementation. The selenium dependent GSH-Px activity in the liver rose with increasing selenomethionine supplementation, but approached a plateau when 0.1 mg Se/kg as sodium selenite was added to the feed. The selenium concentration in whole blood responded more rapidly to the selenium supplementation than did GSH-Px activity. The experiment indicates that the optimal selenium concentration in the feed is considerably higher than 0.1 mg Se/kg, and that selenium levels of 1.0 mg/kg in the feed do not result in any risk for the animals or the consumers of the products.Key words: dietary selenium, lambs, selenium concentrations, glutathione peroxidase activities, tissues     

Vitamin E, selenium, and polyunsaturated fatty acid concentrations and glutathione peroxidase activity in tissues from pigs with dietetic microangiopathy (mulberry heart disease)

Tissues of 27 pigs with spontaneous dietetic microangiopathy (DM) and of 27 control pigs that died of causes unrelated to vitamin E and selenium (E-Se) deficiency were analyzed for alpha-tocopherol, Se and polyunsaturated fatty acid (PUFA) concentrations and for glutathione perioxidase (GSH-Px) activity. These variables (except for GSH-Px) also were measured in rations fed to control pigs and pigs with DM. Swine with DM had lower heart and liver alpha-tocopherol concentrations than did control pigs. Heart and kidney Se concentrations and heart and liver PUFA concentrations were similar in pigs of either group. Diets fed to both groups of pigs contained similar content of alpha-tocopherol, Se, oil, and PUFA; alpha-tocopherol and Se concentrations in the diets of both groups of pigs were high. In spite of apparently adequate amount of dietary alpha-tocopherol, results indicate that pigs with DM had lower tissue alpha-tocopherol concentration than did control pigs. Spontaneous DM is associated with altered alpha-tocopherol metabolism, but is unrelated to alterations in dietary Se and PUFA contents and tissue Se and PUFA concentrations and GSH-Px activity.     

Effects of riboflavin supplementation and selenium source on selenium metabolism in the young pig

The effect of dietary riboflavin (B2) supplementation and selenium (Se) source on the performance and Se metabolism of weanling pigs was studied. Pigs fed a B2-supplemented (10 mg/kg) casein-glucose diet for 18 d gained faster than pigs fed the B2-unsupplemented diet. Percentage active erythrocyte glutathione reductase (GR) declined rapidly when pigs were placed on the B2-unsupplemented diet and was lower (P less than .01) than that of B2-supplemented pigs after 12 d on test. Percentage active erythrocyte GR values fell below 50% before other B2 deficiency signs became evident. Supplementation of diets with 10 mg B2/kg resulted in increased kidney and muscle glutathione peroxidase (GSH-Px) activity. The Se concentration of liver and heart increased and plasma Se levels decreased with dietary B2 supplementation. Riboflavin supplementation and Se source did not alter apparent Se absorption, but B2 supplementation decreased urinary Se and thus increased Se retention. Also, there was less urinary Se excretion when selenomethionine was the dietary Se source and consequently more Se was retained than when sodium selenite was the dietary Se source. In a final trial, B2 supplementation increased kidney, muscle, heart and brain GSH-Px activity when sodium selenite was the dietary Se source, but not when selenomethionine was the dietary Se source.     

Milk and blood levels of silicon and selenium status in bovine mastitis

Milk and blood levels of silicon, selenium and the selenoenzyme glutathione peroxidase (GSH-Px) were measured in 20 healthy and 21 mastitic cows. In milk samples from healthy quarters the mean silicon concentration was 0.81 and in affected ones 0.39 ppm. In serum the mean silicon values were 1.63 and 1.02 ppm respectively. The selenium status was not altered but the level of erythrocyte GSH-Px was lowered in mastitic animals. Silicon is known to have marked effects on free radical formation, lipid peroxidation and macrophage activity. Its possible role in infection and inflammation is evaluated. Some of the functions of silicon may resemble those of selenium. The possibility of lowered levels of silicon and of the selenoenzyme in mastitis calls for experimentation with dietary or pharmaceutical supplementation of these trace elements.     

Assessment of serum thyroid hormone concentrations in lambs with selenium deficiency myopathy

OBJECTIVE: To assess changes in serum concentrations of thyroid hormones associated with selenium deficiency myopathy in lambs. ANIMALS: 35 lambs with selenium deficiency myopathy and 30 healthy lambs. PROCEDURES: Blood samples were collected via jugular venipuncture from lambs with selenium deficiency myopathy and healthy lambs. Activities of markers of selenium deficiency myopathy (erythrocyte glutathione peroxidase [GSH-Px] and plasma creatine kinase [CK]) and serum thyroid-stimulating hormone (TSH) and total thyroxine (tT(4)) and total triiodothyronine (tT(3)) concentrations were assessed; values in affected lambs were compared with those in healthy lambs. Correlations of erythrocyte GSH-Px and plasma CK activities with serum concentrations of TSH, tT(4), and tT(3) were investigated, and the tT(3):tT(4) concentration ratio was evaluated. RESULTS: Compared with findings in healthy lambs, erythrocyte GSH-Px activity, serum tT(3) concentration, and tT(3):tT(4) concentration ratio were significantly decreased and serum concentrations of tT(4) and TSH and the activity of plasma CK were significantly increased in affected lambs. Analysis revealed a significant negative correlation in the affected group between erythrocyte GSH-Px activity and each of the following: plasma CK activity (r = -0.443), serum TSH concentration (r = -0.599), serum tT(4) concentration (r = -0.577), and serum tT(3) concentration (r = -0.621). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that notable changes in circulating amounts of thyroid hormones develop in association with selenium deficiency in lambs. Such alterations in thyroid hormone metabolism may be involved in the high incidence of disorders, such as stillbirths and neonatal deaths, in selenium-deficient flocks.     

Selenium balance in the adult cat in relation to intake of dietary sodium selenite and organically bound selenium

The response of cats to dietary sodium selenite (Na(2) SeO(3)) and organically bound selenium was studied in two separate studies with four cats per treatment and three levels of selenium supplementation (targets 1.0, 1.5 and 2.0 μg/g DM) for each Se source. Whole blood and plasma selenium concentrations and glutathione peroxidase (GPx) activity were determined at 7-time points across the 32-day study. Faeces were quantitatively collected during the last 8 days and urine was collected daily during both studies. The basal diet used had a low apparent faecal selenium absorption of 25.3 ± 3.0%. Daily faecal and urinary selenium excretion increased linearly with increasing selenium intake for both Se sources. Urinary selenium concentration of the cats fed the supplemented diets increased rapidly (～2 days) and remained constant throughout the remainder of the study. Apparent faecal selenium absorption was high for both selenium sources (73.2% and 80.0%). Plasma, and to a lesser extent, whole blood selenium concentrations increased in a dose-dependent manner with supplementation. Whole blood and plasma GPx activity were highly variable and showed a variable response to dietary selenium intake. Cats closely regulate selenium homeostasis through increasing urinary excretion whilst faecal absorption remains unaffected.     

Selenium requirements of dairy goats

Selenium is an essential part of the enzyme glutathione-peroxidase (GSH-Px) and plays an important role in the intracellular aspecific immune defence. Reference values for blood levels of GSH-Px are not available for dairy goats. The EU has authorized the addition of selenium (as E), in the form of sodium selenite or sodium selenate, to animal feeds, to a maximum of 0.5 mg selenium/kg complete feed. Dairy goats given feed containing the maximum level of selenium (0.5 mg/kg) had GSH-Px levels of more than 1000 U/g Hb. The reference values for GSH-Px in cattle, horses, and pigs are between 120 and 600 U/g Hb. Newborn kids had GSH-Px levels between 350 and 400 U/g Hb, comparable with those ofnewborn calves. In conclusion, the addition of selenium to feeds for dairy goats in amounts authorized by the EU leads to blood GSH-Px levels that are substantially higher than those in other species, such as horses, cattle, and pigs. Thus the maximum level of supplemental selenium in feeds for dairy goats should be less than 0.5 mg/kg.     

Studies on serum tocopherol, selenium levels and blood glutathione peroxidase activities in calves with white muscle disease

For the purpose of clarifying the cause of white muscle disease (WMD) in calves, tocopherol and selenium levels and blood glutathione peroxidase (GSH-Px) activity were measured on 10 calves with WMD and nine of their dams. The main clinical symptoms of the 10 calves with WMD were motor disturbances including recumbency and stiffness. Serum enzyme activities (GOT, GPT, CPK, LDH) in calves with WMD increased markedly, and this increase was also observed in some of their dams. Serum tocopherol levels of calves with WMD were low, 70% of which showing deficient levels of less than 70 micrograms/100 ml. Serum selenium levels of all the calves were lower than 35 ppb, indicating a deficiency, and were accompanied by low blood GSH-Px activity. alpha-Tocopherol and selenium concentrations in organs were very low. Dams of calves with WMD showed low serum tocopherol levels, 22% of which indicating deficient levels below 150 micrograms/100 ml. Serum selenium levels in dams showed a marked decrease to under 20 ppb, and also low blood GSH-Px activity. Feedstuffs supplied in the farms to affected calves indicated very low alpha-tocopherol contents (below 3 mg/100g DM) and low selenium concentrations below 50 ppb in DM. It was concluded that WMD in calves was attributable to nutritional muscular dystrophy caused by deficiencies in tocopherol and selenium in feedstuffs supplied to their dams.     

The influence of supplements of selenite, selenate and selenium yeast on the selenium status of dairy heifers.

The aim of the study was to define possible differences between selenite, selenate and selenium yeast on various aspects of selenium status in growing cattle. Twenty-four Swedish Red and White dairy heifers were fed no supplementary selenium for 6 months. The basic diet contained 0.026 mg selenium/kg feed dry matter (DM). After the depletion period the animals were divided into 4 groups; group I-III received 2 mg additional selenium daily as sodium selenite, sodium selenate, and a selenium yeast product, respectively. Group IV, the control group, received no additional selenium. The total dietary selenium content for groups I-III during the supplementation period was 0.25 mg/kg DM. After the depletion period the mean concentration of selenium in blood (640 nmol/l) and plasma (299 nmol/l) and the activity of GSH-Px in erythrocytes (610 mukat/l) were marginal, but after 3 months of supplementation they were adequate in all 3 groups. The concentration of selenium in blood and plasma was significantly higher in group III than in groups I and II, but there was no significant difference between groups I and II. The activity of GSH-Px in erythrocytes did not differ between any of the supplemented groups. The animals in the control group had significantly lower concentrations of selenium in blood and plasma and lower activities of GSH-Px in erythrocytes than those in the supplemented groups. The activity of GSH-Px in platelets was also increased by the increased selenium intake. There was no difference in the concentration of triiodothyronine (T3) between any of the groups, but the concentration of thyroxine (T4) was significantly higher in the unsupplemented control group.     

Effects of Selenium Administration on Erythrocyte and Blood Plasma Glutathione Peroxidase Activity in Goats

The activity of glutathione peroxidase (GSH-Px, E.G. 1.11.1.9.) was determined in heparinized whole blood, blood plasma and washed erythrocytes from goats before and up to 4 weeks after the administration of selenium (0.4 mg/10 kg BW) and vitamin E (20 mg/10 kg BW) or only vit. E (20 mg/10 kg BW). It was found that Se administration caused a significant increase in enzyme activity in whole blood and washed erythrocytes first detected 2 weeks after the intramuscular injection of Se. No changes were observed in plasma from the treated animals. Minor and insignificant changes were seen in the vit. E treated control animals. It is concluded that GSH-Px activity in blood plasma or serum is of no value as a short-term indicator of the selenium status of goats but whole blood is a good indicator of the long-term status.     

Comparative effect of selenium in wheat, barley, fish meal and sodium selenite for prevention of exudative diathesis in chicks

Groups af White Leghorn chicks obtained from dams deprived on selenium (Se), were fed from hatching a low-Se-vitamin E basal diet alone, or supplemented with 0.02, 0.04, 0.06 or 0.08 mg Se/kg diet, as sodium selenite (Na2SeO₃ · 5H₂O), wheat, barley or fish meal. Prevention of the Se-vitamin E deficiency responsive disease exudative diathesis (ED) as it was clinical observed, induction of the plasma Se dependent enzyme glutathione peroxidase (GSH-Px) activity, and Se concentration in the cardiac muscle were observed to be dietary Se level and source dependent. Slope ratio assay was applied to estimate the biological availability of Se in the natural sources relative to Se in sodium selenite. For the prevention of ED, the bioavailability of Se in wheat, barley and fish meal was 99, 85 and 80 %, respectively. The increase in the plasma GSH-Px activity revealed a bioavailability for Se in wheat, barley and fish meal of 79, 71 and 66 %, respectively. Using retention of Se in the cardiac muscle as the bioassay, a bioavailability of 108, 87 and 100 % was calculated for wheat, barley and fish meal Se, respectively.     

外源Se对绵羊孕期体内相关抗氧化酶的影响

比较研究在相同的饲养管理条件下孕期补硒对不同品种绵羊血清中GSH-Px、CuZn-SOD和T-SOD活性的影响。以处于怀孕期的90只蒙古羊、道赛特羊和萨福克羊作为研究对象,通过可见光分光光度法测定GSH-Px、CuZn-SOD和T-SOD活性。结果显示,补Se后各品种羊血清中GSH-Px活力显著增强,与未补Se同品种羊除怀孕2个月时差异不显著（P>0.05）外,其余各期均差异显著（P＜0.05）,怀孕3个月时CuZn-SOD、T-SOD活力显著高于未补Se的同品种羊（P＜0.05）。结果表明补Se能显著提高血清GSH-Px、CuZn-SOD、T-SOD活性,说明补Se对母体维持正常妊娠和增强抗病性具有重要作用。     

Distribution of glutathione peroxidase activity and selenium in the blood of dairy cows.

The distribution of glutathione peroxidase (GSH-Px) activity and selenium concentrations among several components in the blood of dairy cows was examined. Approximately 98% of the GSH-Px activity in peripheral blood was associated with the erythrocytes when enzyme activity was expressed as units per milliliter of blood. The GSH-Px activity expressed per cell was approximately fourfold greater for peripheral leukocytes than for erythrocytes. The cellular component contained a greater proportion (approx 73%) of whole blood selenium than did the plasma. A positive linear relationship (r = 0.958) between blood GSH-Px activity and blood selenium concentrations was found in dairy cattle under practical field conditions.