Serum glutathione peroxidase activity and blood selenium in pigs

Blood serum glutathione peroxidase activity and blood selenium concentration were measured in blood samples from pigs subjected to experimentally induced selenium deficiency and dietary selenium supplementation on graded levels. A highly significant correlation between blood selenium and serum GSH-Px activity in pigs, especially in selenium deficient pigs, was demonstrated. There was also a strong relationship between blood selenium concentration and serum GSH-Px activity in pigs receiving dietary selenium at graded levels. Serum GSH-Px activity exhibited an excellent close-response relationship to dietary selenium. Linear regression analysis showed that the increased serum GSH-Px activity was a function of the dietary selenium concentration. The fitness of serum in monitoring slight changes of the selenium status of pigs with help of the estimation of GSH-Px activity was discussed. The measurement of serum GSH-Px activity seems to provide a useful and rapid means for defining selenium requirements and for identifying selenium deficiency in growing pigs.     

Serum glutathione peroxidase activity reflects short-term increases in selenium intake in goats

The objective of this study was to determine if serum glutathione peroxidase activity reflects short-term changes in the selenium status of goats. Angora goat kids (n=14) were fed pelleted luceme containing 20 microg/kg of selenium, and treated orally with either selenium (0.1 mg/kg of liveweight weekly, as sodium selenate) or de-ionised water. Serum activity of glutathione peroxidase was increased in response to supplementation and differed from that of controls within 24 hours of supplementation. The change in serum glutathione peroxidase activity during the 21 days after the start of weekly supplementation closely followed changes in serum selenium concentration. The results of this study suggest that serum glutathione peroxidase activity reflects the short-term improvement in the selenium status of Angora goat kids following oral supplementation with sodium selenate.     

Relationship between blood selenium concentration or glutathione peroxidase activity, and milk selenium concentrations in New Zealand dairy cows

AIM: To determine the relationships between blood selenium (Se) concentrations or glutathione peroxidase activity (GSH-Px), and milk Se concentrations in dairy cows. METHODS: Seventy-two Friesian dairy cows were either untreated or injected with 0.5, 1.0 or 2.0 mg Se/kg liveweight as barium selenate (BaSeO4) formulations, resulting in 6 groups of animals with mean blood Se concentrations that varied from 212 to 2272 nmol/l. Milk samples were collected on Days 104 and 188, and blood samples were collected prior to treatment and on Days 41, 76, 104, 188, 244, and 292 after Se injection. RESULTS: Significant quadratic relationships between blood Se and milk Se concentrations, as well as blood GSH-Px activity and milk Se concentrations, were evident at Days 104 and 188. Using combined data, these were represented by the equations: milk Se = 27.3 + 0.073 blood Se -0.00001 (blood Se)2; R2=0.79, p<0.005, and; milk Se = 34.8 + 4.99 GSH-Px -0.068 (GSHPx)2; R2=0.79, p<0.005. CONCLUSIONS: The Se status of dairy cows can be assessed from milk Se concentrations. CLINICAL SIGNIFICANCE: Bulk-tank milk Se concentrations could be evaluated as a method to assess the Se status of dairy herds.     

Thyroid hormone concentrations in selenium deficient and selenium sufficient cattle

Selenium deficient calves when compared to selenium supplemented calves had increased plasma thyroxine concentrations and decreased plasma tri-iodothyronine concentrations. These changes in the selenium deficient calves were accompanied by significant increases in plasma urea and creatinine concentrations and decreased plasma alkaline phosphatase activity. The demonstration that low selenium status can cause imbalances in thyroid hormone metabolism may provide an explanation for some of the effects of the deficiency.     

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

For the investigation of the cause of white muscle disease (WMD), tocopherol (Toc) and selenium (Se) levels and blood glutathione peroxidase (GSH-Px) activities were examined using lambs with WMD and their ewes. Serum Se levels of 4 lambs with WMD were low under 30 ppb, lambs showing very low levels below 15 ppb. The serum Se level was correlated with blood GSH-Px activity showing remarkably low activities in the lambs with WMD. Se contents in the organs of lambs with WMD were lower than those of control lambs, and particularly liver Se contents were deficient levels below 50 ppb. Serum Toc levels were normal, but alpha-Toc contents in organs showed very low levels, especially in the liver. The serum Toc and Se levels and blood GSH-Px activities of their ewes and other sheep kept in the same farm revealed similar results to those of lambs with WMD. Feedstuffs supplied on the farm showed the deficient level of the Se content below 50 ppb and a very low level of alpha-Toc. It was concluded that WMD of lambs in Hokkaido was nutritional muscular dystrophy resulted from deficiencies of Toc and Se to their ewes.     

Effect of subcutaneous selenium injection and supplementary selenium source on blood selenium and glutathione peroxidase in feedlot heifers

This study measured the effect on glutathione peroxidase (GSH-Px) and selenium (Se) in whole blood and plasma associated with subcutaneous Se injections in beef heifers fed organic or inorganic Se. Heifers (n = 120) were randomly divided into 2 groups, 1 of which received subcutaneous Se injections. Both groups were given the same total mixed ration with 3 mg of organic or inorganic Se daily. Until week 2, heifers that had received Se injections showed higher concentrations of plasma Se and GSH-Px and whole blood Se (P < 0.001) than those having had no injections. Concentrations of plasma Se and GSH-Px were higher in the group receiving organic Se than the group receiving inorganic Se. Whole blood GSH-Px concentrations increased significantly (P < 0.001) throughout a 12-week period but were not affected by Se source. Combination of Se injections and supplementation could help maintain normal Se and GSH-Px blood status in beef heifers during the first few weeks in the feedlot.     

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).     

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.     

Variation in quantity and quality of native forages and grazing behavior of cattle and goats in Tanzania

The study was conducted to assess the effects of seasonal variation in the quality and quantity of pasture and management of livestock exclosures (ngitili) on the grazing behavior of cattle and goats. The study was 2×2×2 factorial design with three independent variables: season (Dry or Rainy), ngitili management (Private or Communal) and animal species (Cattle or Goats). Focal and scan observation methods were used to record different behavioral activities. Vegetation attributes from the study areas were measured in two consecutive seasons. Most key forage species had significant higher crude protein (CP) content and in vitro organic matter digestibility (INVOMD) in rainy than in dry season (P<0.05), but Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) did not vary significantly with season (P>0.05). ADF and NDF were significantly higher in species from communal ngitili than those from private ngitili (P<0.05). Above-ground herbaceous biomass and bulk density (BD) were significantly higher in the rainy season and in the private ngitili than in the dry season and in the communal ngitili respectively. Cattle and goats spent considerably more time grazing and browsing respectively in the rainy season than in the dry season (P<0.05). Cattle foraging activities did not vary significantly (P>0.05) with ngitili management, but goats found to spend considerably more time browsing in the communal ngitili and more time grazing in the private ngitili (P<0.05). Despite the merits of stocking cattle and goats together in the heterogeneous pasture, seasonal variation in forage resources requires investigation of other strategies such as use of multipurpose trees and treatment of crop residues to improve livestock production.     

The relationship of erythrocyte glutathione peroxidase to blood selenium in swine

The erythrocyte glutathione peroxidase activity and blood selenium have been investigated in swine fed a Se deficient diet with, and without, selenium supplementation. A highly significant correlation (r = 0.90) between erythrocyte glutathione peroxidase and blood selenium was found.     

Serum amylase activity and calcium and magnesium concentrations in young cattle grazing fescue and Bermuda grass pastures.

The study reported here was part of a long-term investigation of the effects of genotype on growth, reproduction, and metabolism in cattle grazing common Bermuda grass and endophyte-infected fescue pastures. In June 1990, blood samples were collected from the tail vein of yearling heifers and steers (Angus [AA], Brahman [BB], and their reciprocal crosses [AB, BA], n = 97). Serum amylase activity was assayed enzymatically; serum Ca and Mg concentrations were determined by atomic absorption spectrophotometry. The effects of endophyte-infected fescue depended on genotype (P less than 0.001). In yearlings having at least 1 Angus parent (AA, AB, BA), grazing endophyte-infected fescue was associated with higher serum amylase activity than was grazing Bermuda grass. But serum amylase activities of BB yearlings consuming either forage were similar. Moreover, for either forage, substantial differences were related to genotype (P less than 0.007) and gender (P less than 0.05). Angus yearlings had higher serum amylase activity than did Brahman yearlings; AB and BA yearlings had intermediate values. Heifers had higher amylase activity than did steers. The relationship among serum values of amylase, Ca, and Mg depended on forage. Yearlings consuming endophyte-infected fescue and having at least 1 Angus parent had a moderate negative correlation between serum amylase activity and Ca concentration (r = -0.53; P less than 0.0005); that is, in calves of genotypes with increased amylase activity while consuming endophyte-infected fescue (AA, AB, BA), the higher the amylase activity, the lower the serum Ca concentration. However, in yearlings consuming Bermuda grass, serum amylase and Ca values were not correlated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transplacental transfer and colostral concentrations of selenium in beef cattle

Three groups of 20-month-old pregnant Hereford heifers received 3 regimens of selenium (Se) supplementation. Group 1 received pelleted alfalfa hay, soybean meal, which contained Se (0.313 mg/kg), and 90 mg of Se as sodium selenite/kg of salt-mineral mix ad libitum. Group 2 received the pelleted hay and soybean meal, and group 3 received only the pelleted alfalfa hay. At time of parturition, the mean whole blood Se concentrations were: group 1 = 0.250 mg of Se/kg of blood, group 2 = 0.162 mg/kg, and group 3 = 0.052 mg/kg, whereas the respective mean blood glutathione peroxidase (GSH-Px) values were 144, 80, and 30 mU/mg of hemoglobin. In comparison, the mean whole blood Se values for the calves were 0.242, 0.175, and 0.81 mg/kg, respectively, and their blood GSH-Px values were 154, 113, and 50 mU/mg of hemoglobin, respectively. Thus, the blood Se and GSH-Px values for each group reflected dietary intake of Se. The calf blood GSH-Px values were similar to their dams for group 1, but were 41% higher in group 2 and 67% greater in group 3. The data suggested that the fetus can sequester blood Se, accumulating values greater than the dam, and that larger amounts were concentrated in the fetus when smaller amounts were available from the dam. The colostrum contained modest to low amounts of Se proportionate to dietary intake of this element. However, milk 7 days after parturient contained inadequate amounts of Se to sustain blood Se values in calves and the milk from heifers with low normal blood Se was essentially void of Se (0.009 mg/kg). (ABSTRACT TRUNCATED AT 250 WORDS)     

Reference values for a field test to estimate inadequate glutathione peroxidase activity and selenium status in the blood of cattle.

A clinical screening procedure was developed for estimating glutathione peroxidase (GSH-Px) activity and selenium status in the blood of dairy and beef cattle. The test is based on the rate of defluorescence under long waveform UV irradiation of reduced nicotinamide adenine dinucleotide phosphate in a coupled enzyme reaction involving glutathione reductase. Defluorescence rates were significantly correlated with blood GSH-Px activity and blood selenium concentrations as determined by conventional laboratory procedures. Blood selenium concentrations and blood GSH-Px activity in several herds were compared with the selenium content of the complete ration consumed to establish reference or base-line values for these blood characteristics under field conditions. The GSH-Px screening procedure provides rapid results, is relatively inexpensive, and appears to be useful in differentiating between the reference values and grossly inadequate selenium status in cattle.     

Comparison of selenium levels and glutathione peroxidase activity in bovine whole blood.

Blood glutathione peroxidase activity and selenium levels were found to correlate well, indicating that glutathione peroxidase activity can be used to assess blood selenium levels in beef cattle. The glutathione peroxidase activity of blood is less stable than is the selenium concentration but when blood was stored at 4 degrees C, the glutathione peroxidase activity remained constant for seven days.     

Effects of high dietary sulphur on enzyme activities, selenium concentrations and body weights of cattle.

This study was designed to assess the effects of a moderate increase in dietary sulphur (S) in cattle. Twelve animals were initially fed a basal concentrate (S = 0.2%) and then divided into two groups; one fed basal and the other high S (S = 0.75%) concentrates. Health, body weight gains, and activities of erythrocyte enzymes-glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), acetylcholinesterase (AChE), plasma- asparate aminotransferase (AST), and whole blood concentrations of selenium (Se) were monitored at various stages of the study. Marked increases in the activities of GSH-Px, SOD and G6PD from the pretrial values were observed upon initial feeding of basal concentrate diet. Sex related differences were not evident in enzyme activities and Se concentrations of the blood. A high linear correlation (r = 0.92) between averages of GSH-Px activity and Se concentration of blood was observed in both sexes. Increasing the amount of S in the concentrate diet (from 0.2 to 0.75%) did not produce any statistically significant change in enzyme activities and Se concentrations, body weight gains, and health of the cattle during the 85 days feeding period. The results indicate that a moderate increase in the dietary S would not impair Se and copper status or cause related disorders in cattle.     

The influence of dietary selenium levels on blood levels of selenium and glutathione peroxidase activity in the horse

Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-Px activities were determined from all blood samples. Selenium concentrations in plasma and whole blood increased linearly from wk 1 to wk 5 and 6, respectively, in Se-supplemented horses. After these times, no significant changes in Se concentration were observed in Se-supplemented or in unsupplemented horses throughout the remainder of the 12-wk trial. Plasma Se reached plateaus of .10 to .11, .12 to .14, and .13 to .14 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Whole blood Se reached plateaus of .16 to .18, .19 to .21, and .17 to .18 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Plasma SeGSH-Px activity was not significantly affected by dietary treatment. Therefore, this enzyme was not a good indicator of dietary Se in these mature horses.     

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.