Effect of parenteral selenium administration to sheep on prevalence and recovery from footrot

Potential benefits of selenium supplementation in patients with kidney disease

Trace element deficiency is common among patients with end-stage renal disease (ESRD); the reason is that since these patients undergo dialysis, they lose these elements more than healthy people, and also the use of trace elements is restricted due to loss of appetite. Selenium (Se) is a trace element that is essential for the oxidative stress defense system. Se deficiency leads to some complications similar to those often seen in ESRD patients, such as all-cause mortality due to cardiovascular diseases, bone loss, uric acid elevation, and anemia. This article aims to review the evidence on consequences of Se deficiency in ESRD patients, as well as effects of Se supplementation in hemodialysis patients. Multiple databases were searched to summarize the available evidence on selenium's role in kidney diseases. Since the complications of ESRD and those of Se deficiency are mostly similar, this triggers the idea that Se deficiency may be considered as a cause of these problems, but it needs to be more assessed that Se deficiency is a single factor or there are other factors participated in. Also the role of Se supplementation on resolving the mentioned complications, needs to be more studied through welldesigned clinical studies.

Feeding selenium-biofortified alfalfa hay during the preconditioning period improves growth, carcass weight, and nasal microbial diversity of beef calves

We previously reported that feeding Se-biofortified alfalfa hay to weaned beef calves in a preconditioning program decreases morbidity and mortality during the feedlot period. To understand the mode of action by which supranutritional Se supplementation supports calf health, we examined the effect of agronomic Se-biofortification on nasal microbiome and fecal parasites. Recently weaned Angus-cross beef calves (n = 30) were randomly assigned to two groups and fed an alfalfa hay-based diet for 9 weeks in a preconditioning program. Alfalfa hay was harvested from fields fertilized with sodium selenate at a rate of 0 or 90 g Se/ha. Calculated Se intake from dietary sources was 1.09 and 27.45 mg Se/calf per day for calves consuming alfalfa hay with Se concentrations of 0.06 and 3.47 mg Se/kg dry matter, respectively. Feeding Se-biofortified alfalfa hay for 9 weeks was effective at increasing whole-blood Se concentrations (556 ± 11 vs 140 ± 11 ng/mL; P < 0.001) and increasing body weight (P_Treatment, = 0.03) in weaned beef calves. Slaughter yield grades were higher for calves that had been fed Se-enriched alfalfa hay during the preconditioning period (P_Treatment = 0.008). No significant differences were observed in fecal parasite load, which remained low. The nasal microbiome and microbiota diversity within calves and across calves expanded from weaning (week 0) to the feedlot period (week 12), which was promoted by feeding Se-biofortified alfalfa hay. Especially concerning was the expansion of nasal Mycoplasmataceae in the feedlot, which reached over 50% of the total microbiota in some calves. In conclusion, we identified dietary Se-biofortified alfalfa hay as a potential promoter of nasal microbiome genome and microbiota diversity, which may explain in part high-Se benefits for prevention of bovine respiratory disease complex in beef calves.

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.

Selenium supplementation restores innate and humoral immune responses in footrot-affected sheep

Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source (organic Se-yeast, inorganic Na-selenite or Na-selenate) and Se-dosage (1, 3, 5 times FDA-permitted level) on FR severity, 120 ewes with and 120 ewes without FR were drenched weekly for 62 weeks with different Se sources and dosages (30 ewes/treatment group). Innate immunity was evaluated after 62 weeks of supplementation by measuring neutrophil bacterial killing ability. Adaptive immune function was evaluated by immunizing sheep with keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. At baseline, FR-affected ewes had lower whole-blood and serum-Se concentrations; this difference was not observed after Se supplementation. Se supplementation increased neutrophil bacterial killing percentages in FR-affected sheep to percentages observed in supplemented and non-supplemented healthy sheep. Similarly, Se supplementation increased KLH antibody titers in FR-affected sheep to titers observed in healthy sheep. FR-affected sheep demonstrated suppressed cell-mediated immunity at 24 hours after intradermal KLH challenge, although there was no improvement with Se supplementation. We did not consistently prevent nor improve recovery from FR over the 62 week Se-treatment period. In conclusion, Se supplementation does not prevent FR, but does restore innate and humoral immune functions negatively affected by FR.

Selenium supplementation alters gene expression profiles associated with innate immunity in whole-blood neutrophils of sheep

Footrot (FR) is a common, contagious bacterial disease of sheep that results in lameness and significant economic losses for producers. We previously reported that sheep affected with FR have lower whole-blood (WB) selenium (Se) concentrations and that Se supplementation in conjunction with routine control practices accelerates recovery from FR. To determine whether oral Se-yeast administered at supranutritional levels (>4.9 mg Se/week) alters the ability of sheep to resist or recover from FR infection, 60 ewes with and 60 ewes without FR were drenched once weekly for 62.5 weeks with 0, 4.9, 14.7, or 24.5 mg organic Se-yeast (30 ewes per treatment group). Footrot prevalence and severity were measured at 0, 20, 28, 40, and 60 weeks of Se supplementation. Genomic expression of eight WB-neutrophil genes for selenoproteins and seven WB-neutrophil genes for proteins involved in innate immunity was determined at the end of the treatment period using SYBR Green and quantitative polymerase chain reaction methodology. Supranutritional Se-yeast supplementation successfully increased Se status in sheep but did not prevent FR. Supranutritional Se-yeast supplementation increased WB-neutrophil expression of genes involved in innate immunity: L-selectin, interleukin-8 receptor, and toll-like receptor 4, which were or tended to be lower in ewes affected with FR. Furthermore, supranutritional Se-yeast supplementation altered the expression of selenoprotein genes involved in innate immunity, increasing selenoprotein S and glutathione peroxidase 4 and decreasing iodothyronine deiodinases 2 and 3. In conclusion, supranutritional Se-yeast supplementation does not prevent FR, but does alter WB-neutrophil gene expression profiles associated with innate immunity, including reversing those impacted by FR.

Higher whole-blood selenium is associated with improved immune responses in footrot-affected sheep

We reported previously that sheep affected with footrot (FR) have lower whole-blood selenium (WB-Se) concentrations and that parenteral Se-supplementation in conjunction with routine control practices accelerates recovery from FR. The purpose of this follow-up study was to investigate the mechanisms by which Se facilitates recovery from FR. Sheep affected with FR (n = 38) were injected monthly for 15 months with either 5 mg Se (FR-Se) or saline (FR-Sal), whereas 19 healthy sheep received no treatment. Adaptive immune function was evaluated after 3 months of Se supplementation by immunizing all sheep with a novel protein, keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity (DTH) skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. Innate immunity was evaluated after 3 months of Se supplementation by measuring intradermal responses to histamine 30 min after injection compared to KLH and saline, and after 15 months of Se supplementation by isolating neutrophils and measuring their bacterial killing ability and relative abundance of mRNA for genes associated with neutrophil migration. Compared to healthy sheep, immune responses to a novel protein were suppressed in FR-affected sheep with smaller decreases in FR-affected sheep that received Se or had WB-Se concentrations above 250 ng/mL at the time of the immune assays. Neutrophil function was suppressed in FR-affected sheep, but was not changed by Se supplementation or WB-Se status. Sheep FR is associated with depressed immune responses to a novel protein, which may be partly restored by improving WB-Se status (> 250 ng/mL).

Parenteral selenium and vitamin E supplementation to lambs: hematology, serum biochemistry, performance, and relationship with other trace elements

Most regions in Iran are generally selenium (Se) deficient and all mineral premixes which used in farm animals contain Se in the form of sodium selenite. The objective of this study was to evaluate the effects of injected Se and vitamin E (vit E) on hematology, serum proteins, and performance of lambs during the period which the animals are at risk of Se and/or vit E deficiency. The study also aims to determine the relationship between selenium injection and the levels of other trace elements in blood serum of lambs. A total of 16 lambs of Baloochi breed (age, 70 ± 7 days and weight, 15.2 ± 1.4) were enrolled in the study. The animals were divided into two groups. In the test group, vit E and Se injected at a dose of 0.2 ml/kg BW (Vetoquinol, Selepherol®, Lure Cedex, France, α-tocopherol acetate 3.82 g/100 ml plus sodium selenite 0.023 g/100 ml) at the enrollment. Control lambs were received equal amounts of normal saline as placebo. Blood was sampled from the jugular vein at the beginning of the study (enrollment, before injection of vit E and selenium and saline) and at days 7, 14, 21, and 28 of experiment. The amounts of total serum protein, albumin, glucose, iron, copper, zinc, creatine kinase (CK), and aspartate aminotransferase (AST) and Se were measured. The concentration of globulin was calculated as the difference between total serum protein and albumin. For evaluation of growth and health, body weight of all the lambs was measured at day 0 of the experiment and the sampling times and days of treatment for each lamb were recorded. Treatment with Se and vit E decreased the activities of CK and AST compared to the controls (p < 0.05). Age (sampling time) had significant effects on the values of Se, iron, zinc, AST, hemoglobin, total protein, glucose, weight, height, and length (p < 0.05). Significant interactions between sampling time and group were seen for CK, AST, iron, glucose, weight, and length. No significant differences were seen for total weight gain (control, 3.48 ± 0.75 kg; test, 3.85 ± 0.9 kg), and average daily gain (control, 0.12 ± 0.03 kg; test, 0.14 ± 0.03 kg) between trial groups.