A survey of whole blood selenium concentrations of horses in Maryland

We surveyed the whole blood selenium status of a randomly sampled population of horses from 4 contiguous counties in northern Maryland. Two hundred and two horses from 74 farms were sampled. Whole blood selenium levels greater than or equal to 0.100 parts per million (ppm) were considered adequate; blood levels less than 0.100 ppm were considered marginal or deficient. The average blood selenium concentration of the horses sampled was 0.137 ppm, with a standard deviation of 0.041 ppm. Blood selenium concentrations ranged from 0.050-0.266 ppm. Thirty-eight of 202 horses (18.8%) had a selenium level less than or equal to 0.099 ppm. Twenty-one of 74 farms (28.4%) had at least 1 horse with a selenium level less than or equal to 0.099 ppm. Animal husbandry practices had a significant influence on selenium status. Horses were more prone to having an abnormal selenium status if they were either maintained on pasture or used infrequently, or if their diet did not include mineral and vitamin supplements.     

Selenium deficiency of beef cattle in Idaho and Washington and a practical means of prevention

The majority of beef cattle assayed for whole blood glutathione peroxidase (GSH-Px) activity in Idaho and Washington were deficient in selenium. Cattle in the more arid sections of these states tended to have higher selenium levels than those in areas with moderate and high rainfall. Animals pastured on irrigated forages had lower selenium concentrations than those grazed on dry land pasture. Cattle were supplemented by the addition of sodium selenite to a salt-mineral mixture. Ninety mg selenium per kg (ppm) salt-mineral mix fed to cattle significantly (P less than 0.001) elevated selenium (GSH-Px) levels well into normal ranges by 3 months when fed to extremely selenium deficient animals. Thirty ppm selenium was insufficient to raise GSH-Px levels into normal ranges. In addition, 20 ppm selenium was insufficient to sustain blood selenium concentrations of selenium adequate animals. Selenium given in the salt-mineral mix provided an effective, economical, and easily regulated source of dietary selenium. This supplement can be provided the entire year even under range conditions. Calves of cows placed on the 90 ppm selenium supplement had significantly (P less than 0.005) improved weaning weights (10 months) and an indication of a decreased incidence of infectious diseases.     

Relation between selenium content and glutathione-peroxidase activity in blood of cattle

To identify a simple method for assessing the selenium demand in cattle, the relationship between selenium content in whole blood and the concentration of the selenium containing enzyme glutathione peroxidase (EC 1.11.1.9; GSH-Px) in red blood cells was studied. On six farms with suspected low soil selenium content, blood samples were collected from groups of calves, yearlings and adults at the end of the housing period and of the grazing period. The data obtained showed a highly significant correlation between the parameters mentioned: GSH-Px (U/g Hb) = 3.261 * Se (micrograms/kg) - 40.553. In growing animals there was a decline in Se supply with age, followed by a gradual recovery in heifers. This was most pronounced on some sandy soils and on peat soil. Seasonal effects could not be demonstrated.     

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.     

Relation between selenium content and glutathion‐peroxidase activity in blood of cattle

Summary

To identify a simple method for assessing the selenium demand in cattle, the relationship between selenium content in whole blood and the concentration of the selenium containing enzyme glutathion peroxidase (EC 1.11. 1.9; GSH‐Px) in red blood cells was studied. On six farms with suspected low soil selenium content, blood samples were collected from groups of calves, yearlings and adults at the end of the housing period and of the grazing period.

The data obtained showed a highly significant correlation between the parameters mentioned: GSH‐Px (U/g Hb) = 3.261 * Se (μg/kg) ‐ 40.553. In growing animals there was a decline in Se supply with age, followed by a gradual recovery in heifers. This was most pronounced on some sandy soils and on peat soil.

Seasonal effects could not be demonstrated.     

The biological selenium status of livestock in Britain as indicated by sheep erythrocyte glutathione peroxidase activity.

The reliability of erythrocyte glutathione peroxidase activity as an indicator of selenium status in livestock is discussed. Based on this measurement, a survey is described of the biological selenium status of sheep on each of 329 farms in Britain. Results showed that 47 per cent of these farms were probably unable to provide grazing livestock with sufficient selenium to maintain blood levels greater than 0.075 microgram per ml. Increased selenium deficiency from the increasing use of home grown feeds as a major constituent of livestock rations may be causally related to the increase of white muscle disease and other selenium responsive diseases in Britain.     

Comparison of 3 methods of selenium assessment in cattle.

Three tests are routinely done to assess blood status of selenium in cattle: serum selenium, whole blood selenium, and glutathione peroxidase. The objective of this study was to compare the various analytical methods for determining blood selenium status in groups of mature cows and beef calves. Twenty to 30 blood samples per herd were collected from 8 beef herds in central Alberta and 1 dairy in Alberta herd twice a year from the spring of 1992 through the fall of 1995, and once from 185 spring calves in 2 beef herds in Saskatchewan. Serum and whole blood samples were submitted to 1 laboratory and whole blood samples were submitted to a 2nd laboratory. Samples for glutathione peroxidase determinations were submitted to a 3rd laboratory. Pearson's correlation coefficients and Cohen's kappa were calculated for each possible comparison among the different measures. The best agreement was observed between serum and whole blood analysis within Laboratory A. The remaining comparisons reflected poor agreement. Comparison of herd-level assessment resulted in better agreement than comparison of individual sample results among laboratories and procedures for all combinations tested. Serum selenium analysis was the only laboratory procedure for which external reference material was utilized. Serum selenium, whole blood selenium, and glutathione peroxidase measure different compartments of the blood selenium pool. The time frame of interest, supplementation practices, and the stability of recent dietary intake determine the optimum assessment method for individual animals or herds. Determination of the serum status or of blood selenium is more consistently measured at the herd-level than for individual samples.     

Epidemiological observations of Zimbabwean theileriosis: disease incidence and pathogenicity in susceptible cattle during Rhipicephalus appendiculatus nymphal and adult seasonal activity.

Fifty-nine Hereford cattle susceptible to tick-borne diseases were used as tracer animals to assess the tick challenge and pathogenicity of Theileria parva under field conditions in Zimbabwe. They were moved periodically in groups of five to three commercial farms (one group consisted of four) during seasons of Rhipicephalus appendiculatus nymphal and adult activity. All tracer cattle were herded together with the farm cattle but were not dipped. The nymphal tick counts were high on two of the farms (up to 2000 per animal) but were very low on the third farm (less than ten per animal). On the three farms, 19 out of 24 (76%) tracers had patent Theileria schizonts. There was a range of clinical manifestations of theileriosis with acute and fatal infections occurring on one farm. The adult R. appendiculatus infestations during the wet season numbered 120-800 per animal on the three farms. The disease transmitted by the adults was very pathogenic on the three farms; 30 out of 35 (86%) had severe theileriosis infections. Cattle, which survived the nymphal diseases challenge, showed various degrees of immunity to subsequent T. parva challenge transmitted by adult ticks. Therefore, 13 out of 18 (72%) of these cattle had a second disease episode and the case fatality rate on the three farms was 46%. The factors which determined the epidemiological status of Theileria challenge on the farms, such as the farming systems and presence of wild animals, are discussed.     

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.     

Prevalence of chronic wasting in Dutch dairy herds with a history of chronic health problems

The prevalence of chronic wasting in cattle in March and April 2000 was studied on 218 dairy farms with a history of health problems accompanied by wasting, following reports in the media suggesting that chronic wasting was a substantial problem on Dutch dairy farms. A telephone call revealed that the health problems had resolved on 41 farms; 16 of these farms had culled all cattle. Two farmers refused co-operation. On the remaining 175 farms the animals were inspected and was completed a questionnaire. A high percentage of culling for of health reasons (on average 18.1% of young stock and adult cattle) and an increased mortality rate (4.8%) were reported on the farms visited. In only two of the 175 inspected herds, more than 20 percent of cattle were found showing signs of wasting. These two herds were identified as 'chronic wasting herds'. The prevalence of such herds was low in this study. Consequently, it is likely that there were very few 'chronic wasting herds' among the whole Dutch dairy population in March/April 2000.     

Decreased blood cell counts were not observed in cattle living in the “difficult‐to‐return zone” of the Fukushima nuclear accident

White blood cells, especially lymphocytes, are susceptible to radiation exposure. In the present study, red blood cell, total white blood cell, and lymphocyte counts were repeatedly measured in cattle living on three farms located in the “difficult‐to‐return zone” of the Fukushima nuclear accident, and compared with two control groups from unaffected areas. Blood cell counts differed significantly between the two control groups, although almost all the values fell within the normal range. The blood cell counts of the cattle in the “difficult‐to‐return zone” varied across sampling times even on the same farms, being sometimes higher or lower than either of the two control groups. However, neither a statistically significant decrease in blood cell counts nor an increase in the rate of cattle with extremely low blood cell counts was observed overall. The estimated cumulative exposure dose for the cattle on the most contaminated farm was within a range of 500–1000 mSv, exceeding the threshold for the lymphopenia. Because of the low dose rate on these farms, potential radiation damages would have been repaired and have not accumulated enough to cause deterministic effects.     

Status of selenium and vitamin E on Norwegian organic sheep and dairy cattle farms

Herbage selenium (Se) concentration is generally low in Norway. It is unknown whether feeding practices on Norwegian organic farms fulfil the dietary needs of Se and vitamin E for sheep and dairy cattle. Therefore we analysed Se in soil and herbage, and Se and vitamin E in animal blood in the indoor feeding season at 14 organic dairy and 14 organic sheep farms. The herbage Se concentration was low. Approximately 50 and 35% of all samples in the first and second cut, respectively, had Se concentrations below the detection limit of 0.01 mg/kg dry matter (DM). The median (10th, 90th percentile) Se concentrations were <0.01 (<0.01, 0.03) and 0.02 (<0.01, 0.06) mg/kg DM in the first and second cuts, respectively. Whole blood Se concentrations were 0.10 (0.04, 0.15) μg/g in dairy cattle and 0.14 (0.03, 0.26) μg/g in sheep. Vitamin E concentrations were 4.2 (2.7, 8.4) mg/l in dairy cattle and 1.3 (0.9, 2.4) mg/l in sheep. None of the soil or plant variables explained the variation in herbage Se concentration, although Se in soil and plant tended to be correlated. Herbage Se concentration was inadequate to meet the dietary Se requirements. Vitamin E requirement was only met in dairy herds. We recommend Se and vitamin E supplementation to ruminants on organic farms.     

Selenium levels of beef cattle in southeastern british columbia relative to supplementation and type of pasture

Moderate to extremely low levels of selenium in hay were related to marginally deficient levels of selenium in sera from cattle in the Windermere Valley of southeastern British Columbia. Deficiency was most pronounced in cattle fed local hay during the winter or grazed on fertilized/irrigated pastures. Cattle on range had adequate levels of serum selenium. When sodium selenite was fed at 1.0 and 3.5 mg per head per day, serum selenium levels increased commensurate with the dose. Clinical observations indicated that a variety of clinical problems disappeared after injection or supplementation with selenium/vitamin E.     

Selenium reference ranges in New Zealand cattle

AIM: To compare serum selenium and liver selenium concentrations with whole blood concentrations in samples taken at the same time from unsupplemented cattle, and to use these comparisons to establish a reference range for use in diagnosing selenium deficiency. METHODS: Selenium was measured in concurrent whole blood, serum and liver samples obtained from cattle in unsupplemented herds in the Manawatu, Waikato and Wairarapa regions of New Zealand. The results were statistically analysed. RESULTS: The revised reference ranges are as follows. [table: see text] CONCLUSION: The serum and liver selenium concentrations used as reference values prior to this study were inaccurate for the detection of selenium deficiency.     

快速斑点实验法在测定绵羊血中谷胱甘肽过氧化物酶和硒的浓度上的应用

本实验利用一种经改进的“斑点实验”法来测定外源NADPH的荧光消失时间,并计算出动物血中谷胱甘肽过氧化物酶(GSHPX,下同)的活性和羊血中硒的浓度。其灵敏度和可重复性实验表明,此种方法可用于牧场上对大量放牧家畜进行血硒水平的快速测定。     

Serum selenium concentrations and glutathione peroxidase activities in cattle grazing forages of various selenium concentrations

In cows from 15 dairy herds (n = 210), serum selenium (Se) concentrations ranged from 0.021 to 0.789 microgram/ml, whereas 0.05 to 0.40 microgram/ml is the reported range for adequate serum Se concentrations in cattle. Serum Se concentrations of dairy cattle appeared to follow a geographic distribution pattern. On the basis of herd mean serum Se concentrations, adequate serum Se concentrations were found in cattle from only 1 of 5 herds grazing forage in the geographic area classified as Se deficient for cattle. Adequate mean serum Se concentrations were found in cattle from 4 of 5 herds located in geographic areas described as having variable forage Se concentrations (Se-marginal areas). Of the 10 herds from these 2 areas, there were only 2 herds in which 95% of the cattle had serum Se concentrations in the Se-adequate range (0.05 to 0.40 microgram/ml). In 2 selected neighboring farms in the Se-deficient area, cattle in 1 herd had adequate serum Se concentrations and cattle in the other herd had less than adequate serum Se concentrations (less than 0.05 microgram/ml). Therefore, more cattle are at risk of developing Se-deficiency disease than is commonly believed and forage of neighboring farms may have different Se concentrations. Serum Se concentrations (up to 0.789 microgram/ml) correlated with glutathione peroxidase enzyme activity; this serum Se concentration (0.789 microgram/ml) is approximately 6.2 times higher than previously reported in dairy cattle. Therefore, RBC glutathione peroxidase activity may be useful in determining the diagnosis of chronic Se toxicosis.     

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.     

Measurement of the status of trace elements in cattle using liver biopsy samples

Serum, plasma, or urine samples are usually used for the measurement of the trace elements copper; zinc, iron, selenium, because these samples are easy to obtain; however; these samples are not always appropriate. For example, it is not possible to measure molybdenum, the major antagonist of copper; in blood or urine. Therefore measurement of trace elements in liver tissue is considered the gold standard. For the assessment of selenium the method of choice remains determination of glutathion peroxidase in erythrocytes and for the assessment of magnesium determination of magnesium in urine. We determined the accuracy and repeatability of measuring trace elements in liver biopsies and whole liver homogenates. The levels of trace elements measured were similar in both preparations (92% agreement). Liver biopsy in live animals is a relatively simple procedure but not common in The Netherlands. Reference levels of trace elements, classified as too low, low, adequate, high, and too high, were established on the basis of our research and information in the literature. In a second study we investigated the practical aspects of obtaining liver tissue samples and their use. Samples were collected from cattle on a commercial dairy farm. Liver biopsy provided additional information to that obtained from serum and urine samples. We prepared a biopsy protocol and a test package, which we tested on 14 farms where an imbalance of trace minerals was suspected. Biopsy samples taken from 4 to 6 animals revealed extreme levels of trace elements.     

Blood Mineral Levels of Cattle in Kenya

Tropical Animal Health and Production - In a survey carried out in cattle on six farms over a period of one year 11•2 per cent of samples had a serum calcium concentration of less than...     

The place of Sanga cattle in dairy production in Uganda

A survey was carried out on milk production and reproductive performance of dairy cattle: 24 farms, with a total of 900 animals and distributed in four agro-ecological zones, were visited every 15 days over 18 months. Cows were fed on natural pastures as the only source of feed, and animal performance was dependent on the season and exhibited a dramatic drop in dry spells. Numeric productivity indices integrating productive performance for settler’s, multipurpose, crop–livestock integrated and modern farms were 0.56, 0.74, 0.69 and 0.63, respectively. Milk productivity was higher on modern farms (6.7 L/cow per day) than in the other systems, and higher with Holstein-Friesian cows (7.7 L/cow per day) than with indigenous cattle (1.8 L/cow per day) or crossbred animals (3.7 L/cow per day). This paper speculates on the opportunity to improve the genetic potential of indigenous cattle, concomitantly with the efforts to adapt exotic cattle to a mountainous equatorial environment.