Effect of vitamin E on the immune system of ewes during late pregnancy and lactation

Redox Status of Pregnant Ewes after Vaccination against Clostridial Diseases

The redox status shortly after the vaccination of pregnant ewes is rather unexploited. Thus, the present study was designed to evaluate the fluctuation of redox status after the administration of the annual booster dose of a polyvalent clostridial vaccine in pregnant ewes, 3 to 4 weeks before lambing, with or without a simultaneous injection of Vit E/Se. In total, 24 pregnant Lacaune ewes 3–4 weeks before lambing were randomly allocated into four equal groups: the V (vaccinated with a polyvalent clostridial vaccine), VE (vaccinated and injected IM with Vit E/Se), E (injected IM with Vit E and Se), and C (neither vaccinated nor injected with Vit E/Se). The study period lasted for 21 days, starting on the day of administration. Four redox biomarkers, the antioxidant capacity (TAC), the thiobarbituric acid reactive substances (TBARS), the reduced glutathione (GSH), and the catalase (CAT) were evaluated in blood samples collected from all ewes before the injections (0 h) and then at 12 (12 h), 24 (D1), and 48 h (D2), and thereafter on days 4 (D4), 6 (D6), 10 (D10), 14 (D14), and 21 (D21). The results reveal that the TAC was the only biomarker evaluated that was significantly affected by group and significantly lower in vaccinated animals (V and VE groups) compared to non-vaccinated (E and C groups). The absence of an increase in the TBARS values after vaccination in groups V and VE indicates the absence of significant oxidative stress. Overall, it can be assumed that annual booster immunizations against clostridial diseases do not impose acute oxidative stress on pregnant ewes in the last month of pregnancy.

The effect of vitamin E treatment on selected immune and oxidative parameters in Kivircik ewes suffering from transport stress

The study aimed to investigate the effects of vitamin E injection for the prevention of transport stress on ewes. Kivircik ewes (2-3 years old, n = 24) were randomly separated into three groups; G1 (Control) and G2 treated with 14 ml. saline as the placebo, G3 treated with 2100 IU/ind. DL-alpha-tocopherol acetate prior to transport. G2 and G3 were transported at 80 km/h for 4 h on a truck. Serum samples were obtained before (T0) and after (T1) transport. Serum cortisol, catalase, IgG, ceruloplasmin, C-reactive protein, complement component 4, interleukin-1 beta, tumour necrosis factor-alpha, glutathione peroxidase (GPx), superoxide dismutase, malondialdehyde analyses performed by ELISA, and serum alpha-tocopherol concentrations were evaluated by HPLC-UV. Wilcoxon and Kruskal-Wallis tests were used for statistical assessments (p < 0.05). Alpha-tocopherol concentrations were founded 1.22 ± 0.82, 0.27 ± 0.14 and 0.14 ± 0.07 µmol/L, respectively, in G1, G2 and G3 at T1. Alpha-tocopherol concentration decreased significantly in G2 between T0 and T1. GPx concentrations were increased twofold in G2 and G3 between T0 and T1 (p < 0.01). As a result, G2 alpha-tocopherol concentrations decreased but, the stress and oxidative parameters tested in this study were not affected by treating 2100 IU/ind. DL-alpha-tocopherol acetate before transport.

Maternal supplementation of twin bearing ewes with calcium and magnesium alters immune status and weight gain of their lambs

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Pregnant ewes have an impaired immune system at around one week prior to lambing and at lambing time.

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Calcium and magnesium supplementation improved antioxidant capacity of growing lambs.

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Calcium and magnesium supplementation improved leukocyte functions in newborn lambs.

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Calcium and magnesium supplementation improved live weight gain of lambs from birth to 4 weeks after birth.

This study investigated the effect of supplementation of ewes with calcium (Ca) and magnesium (Mg) in late gestation and early lactation on the plasma mineral concentration, hormone profile and immunity responses of ewes and their lambs. Twin bearing ewes were allocated between four dietary treatment groups (n = 11 per treatment): control (0.33% DM Ca and 0.28% DM Mg); high Ca (0.72% DM Ca and 0.28% DM Mg); high Mg (0.33% DM Ca, 0.48% DM Mg); and high Ca+Mg (0.66% DM Ca and 0.47% DM Mg), offered as part of a whole ration. Ewes were fed the treatment supplement from around one month prior to lambing to one month after lactation. Blood and urine samples were collected at seven time-points: weekly starting at 5 weeks prior to lambing; within 12 h post lambing (+12 h); and then at fortnightly intervals at 2 week (+2 W) and at 4 week (+4 W) post lambing. Colostrum/milk samples from ewes and blood samples from lambs were collected at +12 h, +2 W and +4 W. Live weight of lambs were measured at +12 h, +2 W and +4 W.

The plasma concentration of PTH, 1,25(OH)₂D₃ and 25(OH)D₃ was lowest at +2 W (P ≤ 0.002). Ewes from the Ca+Mg group had the lowest mean concentration of 1,25(OH)₂D₃ than the other groups (P = 0.005). Magnesium supplementation improved the plasma Mg concentration over time in ewes (P <  0.001) and lambs from the control group had lower plasma Mg concentration compared to the treatment groups at +4 W (P = 0.001). Oxidative burst response in lambs supplemented with Ca tended to be greater at +4 W than the other groups at the same time point (P = 0.051) and Mg supplementation increased total antioxidant capacity (TAC) concentration in lambs (P = 0.040). The average daily weight gain of lambs was 204 g/lamb/d for the Ca group, 207 g/lamb/d for the Mg group, 245 g/lamb/d for the Ca+Mg group which were greater than the control group (148 g/lamb/d) (P < 0.001).

Despite the normal concentration of Ca and Mg in the plasma, supplementation of ewes with Ca and Mg from one month prior to lambing to one month post lambing improved TAC concentration and weight gain in lambs.

Supplementation of Merino ewes with vitamin E plus selenium increases α-tocopherol and selenium concentrations in plasma of the lamb but does not improve their immune function

Vitamin E and selenium have been reported to improve immune function across a range of species. Ewes lambing on poor-quality dry pasture in autumn in Western Australia are at risk of being deficient in vitamin E and selenium at lambing thus predisposing their lambs to deficiencies and increasing the risk of infection and disease. This study tested the hypotheses that (i) supplementation of autumn-lambing ewes with vitamin E plus selenium in late gestation will increase the concentrations of vitamin E and selenium in plasma in the ewe and lamb and (ii) that the increased concentrations of vitamin E and selenium in plasma in the lambs will improve their innate and adaptive immune responses and thus survival. Pregnant Merino ewes were divided into a control group (n=58) which received no supplementation or a group supplemented with vitamin E plus selenium (n=55). On days 111, 125 and 140 of pregnancy ewes in the vitamin E plus selenium group were given 4 g all-rac-α-tocopherol acetate orally. On day 111 the ewes were also given 60 mg of selenium as barium selenate by subcutaneous injection. The concentrations of α-tocopherol and selenium were measured in ewes and/or lambs from day 111 of pregnancy to 14 weeks of age±10 days (weaning). Immune function of the lamb was assessed by analysing the numbers and phagocytic capacities of monocytes and polymorphonuclear leucocytes and plasma IgG and anti-tetanus toxoid antibody concentrations between birth and 14 weeks of age±10 days. Maternal supplementation with vitamin E plus selenium increased the concentration of α-tocopherol in plasma (1.13 v. 0.67 mg/l; P<0.001) and selenium in whole blood (0.12 v. 0.07 mg/l; P<0.01) of the ewes at lambing compared with controls. Supplementation also increased the concentration of α-tocopherol (0.14 v. 0.08 mg/l; P<0.001) and selenium (0.08 v. 0.05 mg/l; P<0.01) in lambs at birth compared with controls. There was no significant effect of supplementation on immune function or survival in the lambs.

Effect of selenium yeast supplementation on naturally acquired parasitic infection in ewes

Gastrointestinal parasites cause substantial economic losses in pasture-based sheep production systems. Supranutritional organic selenium (Se) supplementation may be beneficial because it improves immune responses to pathogens. To evaluate the effect of Se-yeast supplementation on gastrointestinal parasite load, 30 ewes per treatment group were drenched weekly with no Se, 4.9 mg Se/week as Se yeast (maximum FDA-allowed concentration), or supranutritional concentrations of Se yeast (14.7 and 24.5 mg Se/week) starting early fall for 85 weeks. Fecal samples were collected at weeks 63, 66, 78, and 84 and counted for total trichostrongyle-type eggs and Haemonchus contortus eggs (in samples with ≥200 trichostrongyle eggs/g feces). During breeding season (fall), ewes were kept on pasture; ewes receiving 24.5 mg Se/week had lower fecal trichostrongyle egg counts (93 ± 40 eggs/g feces) compared with ewes receiving no Se (537 ± 257 eggs/g feces; P = 0.007) or ewes receiving 4.9 mg Se/week as Se yeast (398 ± 208 eggs/g feces; P = 0.03). In winter, fecal trichostrongyle egg counts decreased, and group differences were not apparent. During lambing season (spring), ewes were kept in the barn and fecal trichostrongyle egg counts increased, although no group differences were observed. However, none of the ewes receiving supranutritional Se yeast, and with trichostrongyle egg counts ≥200 eggs/g of feces, but four of the ewes receiving lower Se dosages had H. contortus egg counts ≥1,000 eggs/g feces (P = 0.04). Our results suggest that supranutritional Se-yeast supplementation may enhance resistance to naturally occurring H. contortus gastrointestinal parasitism in sheep.

The effect of vitamin E supplementation on an experimental Haemonchus contortus infection in lambs

The objective of this study was to investigate the effect of vitamin E supplementation on an experimental Haemonchus contortus infection in lambs. Twenty lambs were stratified into two treatment groups based on fecal egg count. Worm-free lambs, 28-32 weeks of age, were supplemented with vitamin E (d-α-tocopherol) for 12 weeks following the recommendations of the National Research Council for the minimum daily requirement (control; 5.3 IU/kg body weight (BW)/day (d), n=10) or the requirement for optimal immune function (VE10; 10 IU/kg BW/d, n=10). Five weeks following initiation of vitamin E supplementation, lambs were infected with 10,000 H. contortus third stage larvae. Samples were taken weekly to quantify serum α-tocopherol, serum total non-specific immunoglobulin (Ig)G, whole worm antigen specific IgG, packed cell volume (PCV), and fecal egg count (FEC). Expression of cytokine genes IFN-λ and IL-4 were measured in peripheral blood collected prior to slaughter. Lambs were necropsied six weeks after infection and the α-tocopherol concentration of liver, muscle and lymph node were measured as well as abomasal worm burden and histologic evaluation of the abomasum for inflammation and enumeration of eosinophils and globule leukocytes. The livers of VE10 lambs contained slightly more α-tocopherol than control lambs. No differences were observed in serum, muscle or lymph node α-tocopherol concentration, serum IgG or peripheral mRNA expression of IL-4 or IFN-λ between control and VE10 lambs. However, lambs supplemented at 10IU/kg BW/d had a lower PCV reduction, FEC and worm burden 49% less than control lambs. Worm burden was negatively correlated with eosinophil (-0.720, P<0.05) and globule leukocyte count (-0.867, P<0.05). Strong positive correlations were observed within the inflammatory cell response in VE10 lambs that was absent in control lambs. These data indicate that additional vitamin E supplementation resulted in lower worm burden and greater recruitment of innate effector cells to the site of infection. Further studies are necessary to elucidate the mechanism by which vitamin E affects greater recruitment of innate effector cells to the abomasum during gastrointestinal nematode infection of lambs.

Vitamin E status and reproduction in sheep: potential implications for Australian sheep production

Vitamin E concentrations in dried pastures, stubble and most grains are below the recommended requirement of 10–25 mg/kg dry matter (DM). Sheep grazing in an environment when dry pastures and cereal crop stubbles are their primary source of nutrients for a few months have a high risk of developing vitamin E deficiency. If the low vitamin E status coincides with late gestation, the neonate is likely to have a deficiency of vitamin E. Some of the consequences of this are well known, with nutritional myopathy (with high mortality) a risk in young growing sheep unless vitamin E supplements are provided. Vitamin E plays an important role in the management of oxidative stress. Sperm are subject to oxidative damage due to high metabolic rate and high concentration of polyunsaturated fatty acids in their membranes. Oxidative stress may also compromise follicular development and ovarian activity. Vitamin E is also involved with improvement in immune response. For these reasons, vitamin E status is important for reproductive efficiency in both males and females and in the survival of lambs and weaners. In addition, vitamin E deficiency is potentially exacerbated by a lack of other nutrients involved in the management of oxidative stress and immune function, such as selenium (Se) and sulfur amino acids. A Se concentration of 0.1 mg/kg DM in feedstuffs is required to maintain immune competency in sheep. In considering possible consequences for reproduction, further investigation is justified into: (i) effects of low vitamin E, in combination with low levels of other natural antioxidants, on the quality and quantity of sperm produced before and during mating; (ii) follicle development, fertilisation and embryonic mortality in Se-supplemented ewes; (iii) assessment of supplementing formulated antioxidants to rams and ewes during the mating season; (iv) managing oxidative stress in the newborn – consequences of large doses of vitamin E to ewes before parturition to boost lamb reserves; (v) potential benefits to lamb survival through boosting maternal innate immunity; (vi) choices for boosting antioxidant and immune function in ewes and lambs through ‘immune pack’ nutrient options that may target nutrients lacking in dry grass pastures; (vii) the potential role of heat stress in modifying the requirements for, and responses to, vitamin E in extensive grazing systems.