Influence of selenium on antibody production in sheep

Three experiments were carried out, using sheep fed a marginally low selenium diet, to study the effect of selenium supplementation on the antibody response to tetanus toxoid and on the serum IgG concentration. Six groups of three six-month-old lambs were fed a basal diet containing 0.13 mg Se kg-1 supplemented with either 0.1, 0.5 or 1.0 mg Se kg-1, as sodium selenite or as selenomethionine. These animals generally showed enhanced antibody response to tetanus toxoid, parainfluenza-3 virus and Corynebacterium pseudotuberculosis, and their total serum IgG concentrations were higher than in unsupplemented control animals although few responses were statistically significant. In two field studies significantly higher titres to tetanus toxoid were detected in ewes injected with 100 mg selenium as barium selenate, although no influence on serum IgG concentrations was detected. Lambs from selenium supplemented ewes had significantly higher titres to tetanus toxoid than lambs from ewes in the control group. Dietary vitamin E supplementation had a similar effect on the antibody response to tetanus toxoid in ewes, though no additive effect was seen when vitamin E was given together with selenium.     

Enhancement of ovine lymphocyte responses: a comparison of selenium and vitamin E supplementation

Lymphocytes of lambs on a low selenium/vitamin E diet were isolated from peripheral blood, and mitogenic responses to phytohaemagglutinin (PHA) tested in the presence of different doses of sodium selenite and emulsified vitamin E added in vitro. An enhancing effect of selenium was observed at doses of 1 ng/ml or less, and reached a plateau at about 10 ng/ml. Toxic effects were evident beyond 1 micrograms/ml. The stimulatory potential of selenium among lambs was inversely related to their ability to respond to PHA in control cultures but was not related to the blood glutathione peroxidase activity of the animals concerned. Optimal doses of vitamin E added to culture (0.15-1.5 micrograms/ml) elevated responses beyond those seen with selenium, but synergistic effects were not apparent. Similar results were obtained when lymphocytes from deficient, myopathic lambs were cultured with serum from lambs supplemented in vivo, and when PHA responses of untreated and treated lambs were compared. Tests with other phytolectins (concanavalin A and pokeweed mitogen) suggested that the two micronutrients exert a differential influence on lymphocyte sub-populations. It was also concluded that the poor lymphocyte responses seen in myopathic lambs can be readily and rapidly reversed by injection of these nutrients, and that prophylaxis is most effective during the first 6 weeks of life.     

The effects of bovine respiratory syncytial on normal ovine lymphocyte responses to mitogens or antigens in vitro

In the present study peripheral blod mononuclear cells (MNC) obtained from normal uninfected lambs were used to study the possible effects of bovine respiratory syncytial virus (BRSV) on lymphocyte responses to the mitogens, phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM) in vitro. Live BRSV had a depressive effect on the proliferative responses of normal MNC to PHA, Con A and PWM. Inactivated BRSV and a commercial preparation of prostaglandin E2 were also found to depress the proliferative responses of normal ovine MNC to PHA but recombinant tumour necrosis factor-alpha (TNF-alpha) had no such effect. Serum samples obtained from BRSV-infected lambs contained substances inhibitory to PHA-driven lymphocyte blastogenesis. Memory blastogenic responses to border disease virus (BDV) of lymyphocytes obtained from lambs previously primed with BDV were significantly reduced when lymphocytes were exposed to infectious BRSV.     

Cellular immune responses in pigs fed a vitamin E- and selenium-deficient diet.

The effects of dietary restriction of vitamin E (Vit E) and selenium (Se) on lymphocyte proliferation, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC), and on burst respiratory response of stimulated granulocytes as measured by chemiluminescence (CL) were studied in pigs. Six male weanling pigs were maintained for 25 d on a torula yeast-based diet containing no measurable amount of alpha-tocopherol and less than .02 mg of Se per kilogram of feed. Six others received the same basal diet supplemented with 33 IU of DL-alpha-tocopheryl acetate and .2 mg of Se per kilogram of feed. All pigs were inoculated with Salmonella typhisuis on d 21 of the feeding period and killed on d 25. Tests to measure cellular immune functions were performed on cells isolated from blood samples taken on d 21 and 25. After 21 d of feeding, lymphocyte blastogenesis responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen in pigs fed the Vit E- and Se-deficient diet were normal compared with the response in pigs fed the supplemented diet. Moreover, the cytotoxic activity of NK cells, the ADCC response, and the CL response of granulocytes were not affected. After 25 d, a marked suppression of lymphocyte response to mitogens occurred in pigs fed the Vit E- and Se-deficient diet when the cells were cultured in the presence of autologous serum. When fetal bovine serum replaced autologous serum in the cultures, no suppression was observed. No effect on NK activity and ADCC was observed, whereas the CL peak response of granulocytes tended to be higher in pigs fed the deficient diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of alpha-ketoisocaproate on adrenocorticotropin-induced suppression of lymphocyte function in sheep.

Previous studies of the amino acid analogue, alpha-ketoisocaproate (KIC), indicate that it can stimulate lymphocyte blastogenesis and antibody responses of sheep. To determine whether KIC could overcome the effects of adrenocorticotropic hormone (ACTH)-induced lymphocyte suppression, 24 lambs were fed a control diet, a diet supplemented with 0.05% KIC, or a diet supplemented with 0.05% of the parent amino acid leucine. Immune status was monitored by determining lymphocyte blastogenic responsiveness to phytohemagglutinin-P (PHA), concanavalin A (conA), and pokeweed mitogen (PWM) and percentages of T-cell subsets in the blood, using monoclonal antibodies and a flow cytometer. Serum cortisol, insulin, and glucagon concentrations also were determined. After 60 days of consuming the respective diet, lambs were administered either saline solution or ACTH (100 IU) twice daily for 3 consecutive days. Administration of ACTH increased serum cortisol and insulin concentrations; however, no effects were seen for serum glucagon concentration. Compared with saline administration, ACTH administration significantly (P less than 0.05) suppressed mitogen-stimulated lymphocyte blastogenesis by approximately 50%, regardless of the mitogen used, and significantly (P less than 0.01) decreased the percentage of circulating T lymphocytes and decreased (P less than 0.01) the ratio of T4 to T8 cells. Lambs fed KIC had greater PHA- and conA-stimulated blastogenic responses and significantly (P less than 0.05) increased ratio of T4 to T8 cells in the blood, compared with lambs fed the leucine-supplemented diet or the control diet and given corresponding injections. These data indicate that ACTH decreased in vitro lymphocyte blastogenesis and altered the subset ratios of blood lymphocytes in sheep. These changes were partially prevented by feeding KIC.     

Dietary vitamin E (alpha-tocopherol acetate) and selenium supplementation from different sources: performance, ascites-related variables and antioxidant status in broilers reared at low and optimum temperatures

1. This study compared the effect of dietary supplementation with organic or inorganic selenium (Se) sources plus control amounts or large amounts of vitamin E (alpha-tocopherol acetate) in broilers raised at control (20 to 24 degrees C) or low (14.5 to 16.8 degrees C) temperatures after 2 weeks of age. 2. The following dietary treatments were used from one day old. Diet 1, the control diet, comprised a commercial diet containing 0.15 mg/kg inorganic Se and 50 mg vitamin E/kg feed. Diet 2 was the same as diet 1, supplemented with 0.15 mg/kg inorganic Se. Diet 3 was the same as diet 2 but was supplemented with 200 mg/kg vitamin E. Diet 4 was the same as diet 1, but inorganic Se was replaced with 0.30 mg/kg organic Se. Diet 5 was the same as diet 4, supplemented with 200 mg/kg vitamin E. 3. Low temperature reduced the growth rate of broilers; however, at 6 weeks, there were no differences in the body weights of birds fed on organic Se supplemented diets housed at low or control temperature. The feed conversion ratio was significantly affected by low temperature but not by diet. The heterophil/lymphocyte ratio was higher in chicks after one week in the cold, indicating mild stress. Blood triiodothyronine levels were significantly higher in birds after 1 and 4 weeks in the cold but thyroxin was not affected. 4. Organic Se supplementation increased relative lung weight at the control temperature, which might lead to greater respiratory capacity. Relative spleen weight significantly decreased in broilers fed diets supplemented with inorganic Se under cold conditions, a possible indication of chronic oxidative stress. 5. At the low temperature, supplementation with organic Se alone, or with inorganic Se and vitamin E increased glutathione peroxidase (GSHPx) activity and glutathione (GSH) concentration in the liver of broilers, which may indicate increased activity of birds' antioxidant defence against suboptimal environments.     

Effect of dietary selenium and vitamin E on the primary and secondary immune response in lambs challenged with parainfluenza3 virus

This study was conducted to determine the effect of dietary selenium (Se) and vitamin E (Vit E) on various blood characteristics and the primary and secondary humoral immune response of lambs challenged with parainfluenza3 virus (PI3 V). Treatments included: 1) +Se/+Vit E, 2) -Se/+Vit E, 3) +Se/-Vit E and 4) -Se/-Vit E. The basal diet (-Se/-Vit E) was deficient in Se and Vit E. Sodium selenite (.2 mg Se/kg diet) and alpha-tocopherol acetate (20 mg Vit E/kg diet) were added to +Se and +Vit E diets, respectively, to provide adequate levels of each according to NRC recommendations. Following a 10-wk dietary adaptation and depletion period, lambs in all treatment groups were intratracheally inoculated with PI3 V on d 0 and 35 of the 70-d study. Prior to inoculation, whole blood and plasma glutathione peroxidase (GSH-Px) activities were higher (P less than .01) for +Se lambs. Whole blood and plasma GSH-Px increased (P less than .01) after primary viral inoculation in +Se lambs but not in -Se lambs. Serum immunoglobulin M (IgM) concentrations were enhanced (P less than .05) by Se supplementation on d 14, 35 and 49 of the study. Selenium and (or) Vit E did not affect serum immunoglobulin G (IgG) levels. Serum PI3 V antibody titers increased after inoculation on d 0 and 35 in all treatment groups. Titer levels appeared to increase more substantially for +Se lambs after primary inoculation, but increases were greater (P less than .01) for +Vit E lambs after secondary challenge.(ABSTRACT TRUNCATED AT 250 WORDS)     

日粮中添加Se和VE对蛋鸡生产性能及蛋品质的影响

为探索不同剂量的Ｓｅ和ＶＥ对蛋鸡生产性能及蛋品质的影响，我们选用３２周龄罗曼蛋鸡７２只，随机分成６组。在基础日粮含Ｓｅ０．１ｍｇ／ｋｇ基础上，添加Ｎａ２ＳｅＯ３－ＶＥ粉，各组Ｓｅ的添加水平分别是每公斤日粮０、０．５、１．０、１．５、２．０、３．０ｍｇ，ＶＥ添加水平分别是０、４１．６６、８３．３２、１２４．９８、１６６．６４、２４９．９６ＩＵ。实验期８周。结果表明，添加１ｍｇ／ｋｇＳｅ、８３．３２ＩＵＶＥ组鸡产蛋率显著高于其他各组；各组鸡蛋重随Ｓｅ水平的提高有下降趋势，但差异不显著；蛋品质各组差异不显著。     

Dietary selenium increases vitamin E contents of egg yolk and chicken meat

1. The influence of different forms of dietary selenium (Se) on vitamin E (alpha-tocopherol) and Se contents of egg yolk and chicken meat was investigated. 2. Eggs were collected from laying hens subjected to 4 different dietary treatments after 24 weeks of age. Treatments compared the effects of inorganic Se supplementation (selenite) to those of organic (Se-enriched yeast, Se-enriched alga Chlorella) supplements. In a second experiment the effect of the above organic dietary Se supplementation on the alpha-tocopherol contents of meat from broiler chickens was evaluated. 3. Dietary Se supplementation increased the alpha-tocopherol content of egg yolks from 297 mg/kg dry matter in treatment without supplementation to 311 mg/kg when selenium was supplemented as selenite, and to 370-375 mg/kg when organic supplements were used. The Se and alpha-tocopherol contents of breast and thigh meat in broilers were significantly increased by organic dietary Se supplementation. 4. The inclusion of organic dietary Se sources in the diets of laying hens and broilers would enhance the nutritional value (vitamin E and Se contents) of products (eggs and meat) for human consumption.     

Mitogen-induced transformation of sheep and goat peripheral blood lymphocytes in vitro: The effects of varying culture conditions and the choice of an optimum technique

Peripheral blood lymphocytes (PBL) prepared by centrifugation of heparinized sheep or goat jugular venous blood on Ficoll-Triosil were shown to incorporate methyl-[H³]-thymidine ([H³]-Tdr) in vitro in response to lymphocyte mitogens.Optimal conditions for transformation included the culture of 2.5 × 10⁵ viable cells per round bottomed culture well in 250μl medium RPMI-1640 supplemented with fetal calf serum (FCS) at 10% for goat or 15% for sheep lymphocytes. Optimum incorporation of [H³]-Tdr by sheep PBL was recorded after 3–5 days and was achieved in response to 100μg/ml phytohaemagglutinin (PHA), 20μl/ml pokeweed mitogen (PWM), 10μg/ml Concanavalin-A (Con-A) and 50μg/ml bacterial lipopolysaccharide (LPS). For goat PBL the optimum mitogen concentrations were 50μg/ml PHA, 20μl/ml PWM, 5μg/ml Con-A and 50μg/ml LPS. Optimum PHA concentrations were influenced by the level of FCS supplementation, higher concentrations of PHA being required for optimum response when the concentration of FCS was increased.While variability within preparations was small there was considerable variation in the magnitude of the response between preparations, which was sufficient to confound comparisons between different experiments and between animals. The variability between preparations could not be attributed to changes in sensitivity of PBL to mitogens or to the influence of erythrocyte contamination of the PBL preparations. While these results are in general agreement with previous reports of optimal conditions for the measurement of ruminant PBL to mitogens, there are some important differences which are discussed in the context of the available literature.     

Vitamin E status in newborn lambs with special reference to the effect of dl-alpha-tocopheryl acetate supplementation in late gestation

Pregnant ewes were supplemented with dl-alpha-tocopheryl acetate, either as a single intramuscular dose (500 mg two weeks before lambing) or perorally (150 mg daily during 3-4 weeks before lambing). Ewes without such a supplementation were controls. The vitamin E supplemented ewes had nearly twice as high vitamin E (alpha-tocopherol) concentrations as the unsupplemented control ewes at lambing both in serum and in colostrum. The vitamin E concentration in colostrum was 5-11 higher than in milk 1 week after lambing. Both supplementations somewhat increased the vitamin E serum concentration of the newborn lambs, but the increase was negligible in comparison with the effect produced by the consumption of colostrum. All lambs had very low serum concentrations at birth. The lambs from the supplemented ewes had significantly higher serum values than the control lambs 24 h after birth. The ewes had somewhat higher selenium status at birth than their offsprings when evaluated by glutathione peroxidase (GSH-Px) in the erythrocytes. It seems reasonable that nutritional muscular degeneration may arise in newborn lambs with a normal selenium status if their vitamin E status is critical, either because of an inadequate consumption of colostrum or because of a vitamin E deficient diet during pregnancy with a low vitamin concentration of colostrum as a consequence.     

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.     

Mitogen stimulation of lymphocytes in pigs with hereditary vitamin C deficiency

Recently an inherited vitamin G deficiency in the pigs presumably based on an autosomal recessive gene was decribed* Homozygotes are in contrast to heterozygotes and normal pigs unable to synthesize ascorbic acid. In an experiment comprising 3 littermate pigs, 2 homozygous and 1 heterozygous for the vitamin C deficiency gene, the influence of ascorbic acid depletion, and repletion on mitogen stimulation of peripheral blood lymphocytes was studied. Ascorbic acid depletion of the vitamin C dependent pigs resulted in a rapid decline in plasma ascorbic acid. Response of lymphocytes to stimular tion with Concanavalin A (Con A) and phytohemagglutinin M (PHA) decreased more slowly reaching a minimum, which coincidedi with the occurrence of the first clinical symptoms of scurvy. Following resupplementation with vitamin C the plasma content of ascorbic acid rapidly returned to normal, while the lymphocyte response to Con A and PHA stimulation only gradually approached the initial values. The repletion with ascorbic acid caused a transitory increase in the response to pokeweed mitogen (PWM) stimulation. The significance of these findings in relation to the cellular immune system in normal pigs is discussed.     

Use of injectable vitamin E and selenium-vitamin E emulsion in ewes and suckling lambs to prevent nutritional muscular dystrophy

Forty-eight Blackbelly X Dorset, 27 Finnish, 26 Finnish X Dorset, 28 Rambouillet and 8 Dorset Suffolk-sired lambs were used in this experiment. Three weeks before lambing, one-half of the ewes received a selenium emulsion (Se-E) containing .05 mg selenium and 3.7 IU of vitamin E/kg body weight (BW). A 2 X 3 X 2 factorial arrangement was used; lambs from either treated or nontreated ewes were randomly assigned irrespective of breed to one of six treatment combinations consisting of 0 or .025 mg/kg BW selenium (Se) injected at birth or two .025 mg/kg BW Se injections, one at birth and one 2 to 3 wk later, and two levels of injectable Vitamin E (E; 0 and 100 IU) given at birth. Both lambs and ewes were provided access to 75% concentrate diets supplemented with Se and E at recommended NRC levels. Plasma activity of creatine phosphokinase (CPK) was highest at 1 d of age and exhibited decreases (P less than .001) over time. In lambs, the E injection tended to decrease plasma activity of CPK. Plasma glutathione peroxidase activity was lowest at 1 d of age and increased over the course of the experiment but was unaffected by treatments (P less than .05). Plasma tocopherol concentration decreased (P less than .01) with time, with E therapy tending to increase tocopherol concentration. Differences in mean plasma tocopherol concentrations among breeds were also observed (P less than .01). Selenium concentration increased over time and with the E injection (P less than .01). An interaction between ewe and lamb Se-E treatments also was observed (P less than .10), with nontreated lambs from nontreated ewes exhibiting lower Se concentrations than treated lambs from injected ewes. An increase in lamb plasma Se concentration was noted in response to Se-E treatments (P less than .001). In the ewes, plasma tocopherol concentration was lower while Se concentration was higher at 18 d than at 1 d postpartum (P less than .01 and P less than .001, respectively). Milk Se concentration was lower at 18 d than at 1 d (P less than .001) and was higher (P less than .10) in Se-E-treated ewes.     

The effect of selenium and vitamin E on the lymphocytes and immunoglobulin-containing plasma cells in the lymphoid organ and mucosa-associated lymphatic tissues of broiler chickens

The present research has been designed to understand the effect of selenium and vitamin E on the lymphocyte and changes in the frequency of Ig-containing plasma cells in the lymphatic organ and ileum (representative organ for mucosa-associated lymphatic tissues) of different postnatal stages of Kasilla broiler chickens. A routine haematoxylin and eosin (H and E) stain were used to study the histology of the lymphocytic changes, and indirect immunoperoxidase staining method was performed for the study of the distributional and dynamical changes of the Ig-containing plasma cells within the lymphatic tissues and in the ileum of control broilers and in the broilers supplemented with different concentration of selenium and vitamin E in the diet. Histologically, the population of lymphocytes decreased in the lobules of the thymus, medulla of bursal follicles, splenic masses, lymphatic nodules of the cecal tonsil, and villi of the ilium in 0.1 mg and 0.5 mg selenium supplemented broilers in comparison with the control. The population of these cells was found to increase in 150 mg and 300 mg vitamin E supplemented chickens in the present study. In the spleen IgG- and the IgM-containing plasma cells were more than IgA-containing plasma cells. In contrast, in the cecal tonsil and ileum IgA-containing plasma cells were more than IgG- and IgM-containing plasma cells. The frequency of these immunopositive cells were decreased in 0.1 mg and 0.5 mg selenium supplementated chickens, and increased their frequency in the chickens supplemented with 150 mg and 300 mg vitamin E. In the spleen the frequency of IgM-containing plasma cells and both in the cecal tonsil and ileum, the IgG-containing plasma cells were more decreased by selenium supplementation which restored in their population by vitamin E supplementation.     

Response of plasma and tissue D-alpha-tocopherol in sheep to graded dietary levels of dl-alpha-tocopheryl acetate

The objective of this experiment was to establish the validity of using plasma alpha-tocopherol values as an index of alpha-tocopherol status in sheep. alpha-tocopherol values were obtained for tissues and blood of 40 sheep given four different dietary intakes of dl-alpha-tocopheryl acetate. Group 1 sheep were given a basal diet containing 25 to 32 mg dl-alpha-tocopheryl acetate kg-1 while groups 2, 3 and 4, comprising 10 sheep each, received the basal diet plus 200, 400 and 600 mg dl-alpha-tocopheryl acetate per sheep, respectively. Blood samples were obtained at zero time and then twice weekly for eight weeks, at which time sheep were killed and organs retrieved for tissue alpha-tocopherol analysis. Tocopherol concentrations were higher in all tissues (P less than 0.001) of sheep fed the vitamin E supplemented diets than the basal diet. Vitamin E stored in the liver of sheep at the end of the experiment (eight weeks) showed a linear response to the level of vitamin E in the diet. Blood plasma vitamin E concentrations increased following vitamin E supplementation, but no direct relationship was found between vitamin E intake and plasma vitamin E content.     

B and T lymphocytes in the bovine mammary gland: Rosette formation and mitogen response

Characterization of lymphocyte subpopulations in the bovine mammary gland was accomplished using cells obtained from dry secretions. Correlation of cell surface properties with functional capacity was attempted by assaying the ability to form erythrocyte-antibody (EA) rosettes, erythrocyte-antibody-complement (EAC) rosettes, and sheep erythrocyte (E) rosettes and the ability to respond to phytohemagglutinin (PHA), Concanavalin A (Con A), and pokeweed mitogen (PWM) in the lymphocyte stimulation test. Results were compared with those obtained for peripheral blood lymphocytes (PBL) from the same animals. Mammary gland lymphocytes (MGL) formed significantly fewer (p < .01) EA and EAC rosettes, but significantly greater (p < .01) E rosettes compared to PBL. MGL were significantly less responsive (p < .05) to mitogens than were PBL. MGL contained a large proportion of T lymphocytes, which do not respond to T lymphocyte mitogens in culture.     

Role of thiamine status in sulphur induced polioencephalomalacia in sheep.

The effects of excess dietary sulphur were studied in sheep supplemented and unsupplemented with thiamine. The diets contained either 0.19 per cent sulphur (LS) or 0.63 per cent sulphur (HS) in combinations with 14 mg kg-1 thiamine (LB1) or 243 mg kg-1 thiamine (HB1). A total of 56 two-month-old lambs were used. Groups consisting of nine, nine, 22 and 16 lambs were fed LS-LB1, LS-HB1, HS-LB1 and HS-HB1 diets, respectively for 14 weeks. Out of 22 lambs fed the HS-LB1 diet, seven lambs developed neurological signs between the third and eighth week of the trial. Two of these lambs died, three that were in extremis were euthanased, and two recovered completely. All clinically affected animals had extensive malacic lesions in the cerebral cortex, midbrain and brainstem. None of the lambs from the LS groups or HS-HB1 group developed clinical signs. Several clinically normal lambs from the HS-LB1 group had necrotic lesions in their brains at gross and microscopic examination. Supplementation with dietary thiamine prevented development of clinical signs, but did not totally prevent development of microscopic brain lesions. Brain thiamine concentration, transketolase activity and thiamine pyrophosphate (TPP) effect were not different (P greater than 0.05) among groups. There was a strong effect (P less than 0.0001) of dietary thiamine supplementation on blood thiamine concentration and TPP effect. Blood thiamine concentration was higher whereas TPP effect was lower in the thiamine supplemented sheep. Blood and tissue thiamine concentrations in sheep exposed to high dietary sulphur did not indicate either systemic or local thiamine deficiency per se. Increased TPP effect in sheep fed the HS-LB1 diet indicated mild to moderate metabolic thiamine deficiency. Thiamine inadequacy may be an effect of an increased requirement for thiamine in animals exposed to excess dietary sulphur.     

Down-regulation of GPx1 mRNA and the loss of GPx1 activity causes cellular damage in the liver of selenium-deficient rabbits

The effects of 10 weeks of dietary selenium and/or vitamin E deficiency (< 0.03 mg Se and 1.5 mg vitamin E per kg diet) on body Se and vitamin E stores and on the down-regulation of liver cellular glutathione peroxidase (GPx1) and plasma glutathione peroxidase (GPx3) were examined in growing female New Zealand White rabbits in comparison to Se (+ 0.40 mg Se/kg diet) and/or vitamin E (+ 150 I.U./kg diet) supplemented controls. Additionally plasma lactate dehydrogenase (LDH) activity, liver thiobarbituric acid-reactive substances (TBA-RS) and liver protein carbonyls were measured to assess the development of oxidative stress during an alimentary Se and/or vitamin E deficiency. Significantly decreased concentrations of Se and vitamin E in plasma (Se: − 70%; vitamin E: − 87%) and liver (Se: − 90%; vitamin E: − 95%) indicated an efficacious Se and vitamin E depletion of the rabbits within 10 weeks. GPx1 messenger RNA levels (GPx1 mRNA) in the livers of Se-depleted rabbits were down-regulated to 1/3–1/8 of the Se supplemented controls. GPx1 enzyme activity in the livers of Se-deficient rabbits declined to 10% of the Se-supplied control rabbits. A significantly elevated LDH activity in the blood plasma of Se- and vitamin E-deficient rabbits indicated a general impairment of tissues. Markedly increased TBA-RS concentrations and protein carbonyl contents in the livers of Se- and vitamin E-deficient rabbits gave further evidence for severe oxidative damage of cellular lipids and proteins during an alimentary Se and/or vitamin E deficiency. Both a full expresssion of GPx1 attained by dietary Se supplementation and dietary vitamin E supply effected an almost complete protection against oxidative cellular damage of the liver.     

Selenium, vitamin E and vitamin A status in dairy sheep reared under different feeding systems in Greece

The main purpose of the study was to investigate whether the feeding system applied has any effect on the status of blood selenium (Se) and vitamins A and E in dairy sheep. In total 200 dairy sheep from 10 flocks were used in the study (20 animals per flock). Group A consisted of 100 sheep (five flocks) reared under the intensive feeding system and group B of 100 sheep (five flocks) reared under the semi-intensive feeding system. The 100 sheep of each group consisted of 25 lambs aged 3-6 months, 25 ewes 1-3 years, 25 ewes more than 3 years and 25 non-lactating ewes in late gestation. Another purpose was to evaluate the potential effect of the age and the reproductive stage of the animals on these parameters. To determine the effect of age, 150 of these animals were divided into three subgroups: 50 lambs, 50 non-pregnant lactating ewes aged 1-3 years and 50 non-pregnant lactating ewes aged more than 3 years. For the evaluation of the effect of the reproductive stage the 50 non-lactating ewes in late gestation and the 100 non-pregnant lactating ewes were used. Blood samplings were performed once, between December and January for non-lactating ewes in late gestation and March to May for lambs and lactating ewes. Whole blood Se and vitamin E and A serum concentrations were determined. The main conclusion is that the feeding system significantly affects Se and serum vitamin A concentration, as they were higher in the intensive one. It was secondly concluded that age affects the serum concentrations of vitamin A.