Dietary Selenium Levels Research Articles

58 The Effect of Altering Dietary Manganese and Selenium Levels on the Growth Performance and Blood Manganese-superoxide Dismutase Activity in Nursery Pigs

Abstract The objective of this study was to determine the effect of altering dietary levels of manganese and selenium on growth performance and MnSOD specific activity. Weaned piglets were blocked by weight (n = 216; 5.21 ± 1.17 kg; 21 ± 3 d) and sex (2 barrows and 2 gilts/pen). Pens within a block were randomly assigned to dietary treatments in a factorial design with main effects of Se (0.1 and 0.3 ppm) and Mn (0, 12, and 24 ppm). Diets (n = 9 pens/treatment) were fed in three phases (P1 = d 1–7, P2 = d 7–21, P3 = d 21–35). Pigs and orts were weighed weekly and pigs were bled on d 0, 7, 21, and 35 for analysis of specific activity of red blood cell MnSOD. Data were analyzed as 2x3 factorial design via SAS PROC GLM. There were no Se effects or Mn x Se interactions observed. There was a linear increase (P < 0.05) in overall ADG (397, 424, and 438 g day-1pig-1 for 0, 12, 24 ppm Mn, respectively). There was a linear trend (P < 0.1) in overall ADFI (557, 560, 592 g day-1pig-1 for 0, 12, 24 ppm Mn, respectively). Feed efficiency (d 0–35) across increasing Mn levels were 0.71, 0.76, 0.74 (P > 0.1). MnSOD activity in RBC increased from d 0–7, peaked on d 7 and decreased to d 35. On d 7, diets with 12 and 0 ppm Mn had significantly increased (P < 0.05) MnSOD activity (0.91 and 0.87 IU mg-1 protein, respectively) compared to diets with 24 ppm Mn (0.67 IU mg-1 protein). The dietary treatment that best maintained MnSOD activity was 0.3 ppm Se and 12 ppm Mn supplemented, while ADG was maximized in the diet with 0.3 ppm Se and 24 ppm Mn supplementation.

A systematic review and dose-response meta-analysis of exposure to environmental selenium and the risk of type 2 diabetes in nonexperimental studies

Accumulating evidence from both experimental and nonexperimental human studies in the last 15 years indicates that exposure to high levels of the trace element selenium increases the risk of type 2 diabetes. However, the relation of dose to effect is not well understood because randomized controlled trials used only one dose (200 μg/day) of selenium supplementation. While no new trial on this topic has been published since 2018, several nonexperimental studies have appeared. We therefore updated a previous meta-analysis to include recently published observational studies, and incorporated the recently developed one-stage random-effects model to display the dose-response relation between selenium and type 2 diabetes. We retrieved 34 potentially eligible nonexperimental studies on selenium and diabetes risk up to April 15, 2021. The bulk of the evidence indicates a direct relation between blood, dietary and urinary levels of selenium and risk of diabetes, but not with nail selenium, which may be considered a less reliable biomarker. The association was nonlinear, with risk increasing above 80 μg/day of dietary selenium. Whole blood/plasma/serum selenium concentrations of 160 μg/L corresponded to a risk ratio of 1.96 (95% CI 1.27–3.03) compared with a concentration of 90 μg/L (approximately 60 μg of daily selenium intake). The cohort studies, which are less susceptible to reverse causation bias, indicated increased risk for both blood and urine selenium levels and dietary selenium intake, whereas no such pattern emerged from studies relying on nail selenium content. Overall, the nonexperimental studies agree with findings from randomized controlled trials, indicating that moderate to high levels of selenium exposure are associated with increased risk for type 2 diabetes.

Effect of Maternal Dietary Redox Levels on Antioxidative Status and Immunity of the Suckling Off-Spring.

This study investigates two levels of dietary selenium (Se) and vitamin E in combination on their status in sows and their progeny, and influence on antioxidant status and immunological responses of the piglets at weaning. Female pigs (n = 6) were provided LOW or HIGH antioxidant nutrition (Se and vitamin E) from mating until weaning of their off-spring. The HIGH treatment elevated the concentration of Se (p = 0.015) and α-tocopherol (p = 0.023) in plasma of piglets compared with piglets of the LOW treatment. Treatments also affected the concentrations of milk and sow plasma immunoglobulins. Piglets from sows on the HIGH treatment had increased (p < 0.001) activity of glutathione peroxidase, lower serum levels of C-reactive protein (p = 0.005), haptoglobin (p = 0.05) and albumin (p = 0.05), and the number of white blood cells (p = 0.023) and the ratio of NEU to LYM was lower (p = 0.025) than in piglets from sows on the LOW group. Furthermore, the dietary antioxidant level influenced responses of cytokines (interleukine (IL) 6 (p = 0.007), 12 (p = 0.01) and 18 (p = 0.01)) in piglets’ plasma. In conclusion, improved antioxidant status via dietary maternal provision improves the robustness of the offspring via immunomodulatory mechanisms.

Growth, physiological, biochemical, and molecular responses of Pacific white shrimp Litopenaeus vannamei fed different levels of dietary selenium

This study investigated the effects of different levels of dietary selenium (Se) on the growth, antioxidant capacity, hepatopancreas health, and transcriptional-level responses of Litopenaeus vannamei. Sodium selenite was added to basal diet formulations at 0, 0.2, 0.4, and 0.8 mg/kg, with final Se concentrations of 0.13, 0.20, 0.45, and 0.81 mg/kg, respectively. Shrimp were fed the experimental diets for 8 weeks, after which the following parameters were measured: growth performance, antioxidant enzymes activity, ALT, AST activity, endoplasmic reticulum stress and transcriptome. Shrimp fed the 0.45 and 0.81 mg/kg Se diets (P < 0.05) showed the highest weight gain, shrimp fed the 0.13 mg/kg Se diet had the highest hepatosomatic index (P < 0.05), and the endoplasmic reticulum stress related genes were down-regulated (P < 0.05) in shrimp fed the 0.45 mg/kg Se diet. Antioxidant enzyme activity (SOD, CAT, and GPx) was enhanced with the increase in the Se level. The transcriptome results showed that glycine, serine, and threonine metabolism, the pentose phosphate pathway, and ascorbate and aldarate metabolism were enriched in shrimp fed the 0.45 mg/kg Se diet, while focal adhesions, gap junctions, tight junctions, and adhesion junctions were found in shrimp fed the 0.13 and 0.81 mg/kg Se diets. Co-expression analysis showed that genes PINK1 and Innexin (among others), were involved in the influence of Se levels on shrimp. Our results suggested that Se supplementation improved the growth and antioxidant capacity of L. vannamei by promoting the biosynthesis of glutathione and enhancing the activity of antioxidant enzymes. However, high levels of dietary Se can cause endoplasmic reticulum stress and hepatopancreas tissue damage.

Effect of organic selenium dietary supplementation on quality and fertility of cryopreserved chicken sperm

Oxidative stress due to cryopreservation has been considered as a major factor in sperm damage. Supplementation of the diet with different concentrations of organic selenium has been proposed to improve the quality of fresh and frozen–thawed semen in different breeds of roosters. Sixteen Pradu Hang Dum (Thai native) and 16 Rhode Island Red roosters were used in this study. Four levels of selenium supplementation between 0 and 0.9 ppm were examined. After 14 days of feeding, semen samples were collected twice a week and the fresh semen was evaluated. Then semen from each group was pooled and cryopreserved. The fertility of frozen–thawed semen was determined by inseminating 48 layer hens. Supplementation of diets with 0.3, 0.6 and 0.9 ppm selenium improved the fresh semen in terms of sperm viability and normal morphology (P < 0.01). Sperm concentration increased (quadratically, P < 0.001) with increasing dietary selenium levels. Meanwhile, post-thawed semen quality in terms of sperm motility, viability, live with intact acrosome and functioning mitochondria improved significantly with selenium treatments of 0.6 and 0.9 ppm, and lipid peroxidation was decreased (P < 0.001) and fertility improved (P < 0.05) with those levels of selenium treatment. In addition, there were differences between breeds with respect to some fresh or frozen semen quality parameters (P < 0.05). In conclusion, the breed affected both fresh and frozen semen. Even there were no statistically significant differences in the parameters from groups 0.6 and 0.9 ppm on frozen-thawed semen quality, but the highest sperm concentration was found in 0.6 ppm. Therefore selenium supplementation of diets at 0.6 ppm was recommended to improve the quantity and quality of fresh and frozen semen.

PSVIII-9 Effects of different sources and levels of dietary iron and selenium on the postprandial net portal appearance of these minerals in pigs

Abstract This study compares the post-absorptive levels of iron (Fe) and selenium (Se) in pigs fed different sources and levels of these minerals. Twelve 55-kg pigs were surgically equipped with portal and carotid catheters and a portal ultrasonic flow probe and used in a cross-over design to assess the 11-hours net portal-drained viscera (PDV) flux of serum Fe and Se after ingestion of boluses containing adequate (A; 200 and 0.6 mg) or high (H; 400 and 1.2 mg) levels of these minerals from dietary inorganic (I) or organic (O) sources. Arterial Fe concentrations increased (158 %) within the first six hours post-meal and gradually decreased thereafter (P &amp;lt; 0.01). Values for I were greater than O until six hours post-meal (P &amp;lt; 0.01) and for A than H between five and eight hours post-meal (P ≤ 0.01). There was a tendency for the interaction source x level (P = 0.07) on net PDV fluxes of Fe where values for AI were greater than AO (P = 0.02). The cumulative Fe PDV appearance (% of intake) was greater for I (2.2 %) than O (-1.7 %) after four hours post-meal (P = 0.02) but this effect was no longer detected at 11 hours post-meal. Arterial Se concentrations decreased by 7 % from pre-meal values until 11 hours post-meal (P &amp;lt; 0.01) and this decline was more pronounced for O than I (P = 0.03). Net PDV flux of Se was positive but only during the first 90 minutes post-meal (P &amp;lt; 0.01). The cumulative Se PDV appearance (% of intake) was greater for I (20.0 %) than O (-3.8 %) at 45 minutes post-meal (P = 0.04) but this effect did not persist thereafter. In conclusion, net availability of Fe and Se was greater for I than O during the early post-meal period. Whether these results reflect non-absorption or greater O intestinal retention remains to be elucidated.

Dietary Intake and Serum Selenium Levels Influence the Outcome of HTLV-1 Infection.

Human T cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP), as the most common neurological emersion related to HTLV-1, is a debilitating and lifelong treating disease with no definitive treatment. Furthermore, it has been determined that dietary compositions (inflammatory and anti-inflammatory) and some micronutrients (such as vitamin D and selenium) have an effect on inflammatory and immune processes and with this background; the study was done to compare the nutritional status between age- and sex-matched with infected and non-infected HTLV-1. In a multi-center setting, 70 healthy controls (HCs), 35 asymptomatic carriers (ACs), and 35 HAM/TSP patients were recruited in the HTLV-1 Foundation, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. Nutritional status including anthropometric indices, dietary (micro- and macronutrient) intake, and serum vitamin D, vitamin B12, zinc, and selenium were measured. In anthropometric indices, mean waist circumference (WC) in the carrier group was significantly higher than the patient and the control groups (p = 0.008). In the dietary intake, the patient group received less energy, protein, mono-unsaturated fatty acids (MUFA), and oleic, but more fat than the HTLV-1 carrier and control groups, and these differences were remarkable in three groups (p = 0.002, 0.005, 0.001, 0.01, and 0.001, respectively), whereas the carrier group received more saturated fatty acid and less poly-unsaturated fatty acids (PUFA), linoleic, and linolenic than patient and control groups with a different significant (p = 0.01, 0.007, 0.005, and 0.006, respectively) in three groups. In micronutrient intake, although selenium, zinc, and vitamins B12 and D were lower in the patient group than the carrier and control group, however, no significant differences were observed. In comparison with micronutrient serum concentrations, vitamins B12 and D and selenium in the patient group were lower than the carrier and control groups, but statistically, the considerable difference was found only in the selenium concentration (p = 0.001). The study showed that there were differences in dietary intake (including energy, macronutrients, and fatty acids), WC, and selenium serum levels between HAM/TSP patients and HTLV-1 carriers, suggesting that nutritional statues influence the inflammatory immune response in HTLV-1 infection.

The effect of feeding different sources and levels of selenium on growth performance and antioxidant status of broilers raised at two different temperatures

ABSTRACT 1. This study examined the effects of different dietary sources and levels of selenium (Se) on growth performance, hepatic and breast meat Se content, glutathione peroxidase (GSH-Px) activity and total antioxidant status (TAS) in blood, when fed to broilers from 14 to 35 d of age and reared at two different temperatures (20°C and 35°C). 2. Five hundred and sixty male Ross 308 broilers were reared in a single floor pen and fed the same proprietary starter diet from 0 to 14 d age (229.9 g/kg CP and 12.67 MJ/kg ME, without Se supplementation). 3. The experiment started at 14 d age, and the birds randomly assigned to 112 raised-floor pens (0.36 m2 area, 5 birds/pen). Each of the seven experimental diets were offered to birds in 16 pens within four rooms. Two rooms were at 20°C and two rooms were maintained at 35°C. The experimental diets were fed from 14 to 35 d age and contained 214.9 g/kg CP and 13.11 MJ/kg ME. The experimental diets were as follows; control diet containing background Se only (0.189 mg/kg; C); low level sodium selenite (0.376 mg/kg; LSS): high level sodium selenite (0.558 mg/kg; HSS); low level commercial B Traxim® Se (0.244 mg/kg) (LBT); high level B Traxim® Se (0.448 mg/kg; HBT); low level selenised yeast (0.290 mg/kg; LSY); high level selenised yeast (0.487 mg/kg; HSY). 4. Birds consumed more when raised at 20°C compared to birds reared at 35°C (P ≤ 0.05). Birds fed lower Se level reared at 35°C had higher weight gain versus those fed higher Se level (P < 0.05). Birds fed SY had the lowest feed intake, weight gain and FCE (P < 0.05). The greatest GSH-Px activity was observed in birds fed SS diets (P < 0.001). There were interactions between diet x level for TAS, which were highest in birds fed LBT compared to birds fed HBT (P < 0.05). Breast Se content was higher in birds fed HSY compared to LSY (P < 0.001). The highest hepatic Se was seen in birds fed SY and lowest in C (P < 0.001). 5. Birds fed BT diets showed similar levels of Se to those birds fed inorganic Se, and similar levels of GSH-Px to birds fed SY. Further comparative work with broilers fed BT and other Se supplemented diets may elucidate the findings from this report.

Selenium Status in Diet Affects Acetaminophen-Induced Hepatotoxicity via Interruption of Redox Environment.

Aims: Drug-induced liver injury, especially acetaminophen (APAP)-induced liver injury, is a leading cause of liver failure worldwide. Mouse models were used to evaluate the effect of microelement selenium levels on the cellular redox environment and consequent hepatotoxicity of APAP. Results: APAP treatment affected mouse liver selenoprotein thioredoxin reductase (TrxR) activity and glutathione (GSH) level in a dose- and time-dependent manner. Decrease of mouse liver TrxR activity and glutathione level was an early event, and occurred concurrently with liver damage. The decreases in the GSH/glutathione disulfide form (GSSG) ratio and TrxR activity, and the increase of protein S-glutathionylation were correlated with the APAP-induced hepatotoxicity. Moreover, in APAP-treated mice both mild deprivation and excess supplementation with selenium increased the severity of liver injury compared with those observed in mice with normal dietary selenium levels. An increase in the oxidation state of the TrxR-mediated system, including cytosolic thioredoxin1 (Trx1) and peroxiredoxin1/2 (Prx1/2), and mitochondrial Trx2 and Prx3, was found in the livers from mice reared on selenium-deficient and excess selenium-supplemented diets upon APAP treatment. Innovation: This work demonstrates that both Trx and GSH systems are susceptible to APAP toxicity in vivo, and that the thiol-dependent redox environment is a key factor in determining the extent of APAP-induced hepatotoxicity. Dietary selenium and selenoproteins play critical roles in protecting mice against APAP overdose. Conclusion: APAP treatment in mice interrupts the function of the Trx and GSH systems, which are the main enzymatic antioxidant systems, in both the cytosol and mitochondria. Dietary selenium deficiency and excess supplementation both increase the risk of APAP-induced hepatotoxicity.

Characterization and expression analysis of seven selenoprotein genes in yellow catfish Pelteobagrus fulvidraco to dietary selenium levels

BackgroundSelenium (Se) appears in the selenoproteins in the form of selenocysteine (Sec) and is important for the growth and development of vertebrates. The present study characterized seven selenoproteins, consisting of the GPX1, GPX3, GPX4, SELENOW, SELENOP, TXNRD2 and TXNRD3 cDNAs in various tissues of yellow catfish, explored their regulation to dietary Se addition. Methods3′ and 5′ RACE PCR were used to clone full-length cDNA sequences of seven selenoprotein genes (GPX1, GPX3, GPX4, SELENOW, SELENOP, TXNRD2 and TXNRD3). Their molecular characterizations were analyzed, including conservative motifs and the SECIS elements. The phylogenetic trees were generated through neighbor-joining (NJ) method with MEGA 6.0 with 1000 bootstrap replications. Quantitative real-time PCR was used to explore their mRNA tissue distribution in the heart, anterior intestine, dorsal muscle, head kidney, gill, liver, brain, spleen and mesenteric fat. Yellow catfish (mixed sex) were fed diets with dietary Se contents at 0.03 (low Se), 0.25 (adequate Se) and 6.39 (high Se) mg Se/kg, respectively, for 12 weeks, and their spleen, kidney, testis and brain were used for the determination of the mRNA levels of the seven selenoproteins. ResultsThe seven selenoproteins had similar domains to their corresponding members of other vertebrates. They were widely expressed in nine tissues, including heart, liver, brain, spleen, head kidney, dorsal muscle, mesenteric fat, anterior intestine and gill, but showed tissue-dependent expression patterns. Dietary Se addition affected the expression of the seven genes in spleen, kidney, testis and brain tissues of yellow catfish. ConclusionTaken together, our study demonstrated the characterization, expression and regulation of seven selenoproteins, which increased our understanding of the biological functions of Se and selenoproteins in fish.

Analysis of Selenoprotein Expression in Response to Dietary Selenium Deficiency During Pregnancy Indicates Tissue Specific Differential Expression in Mothers and Sex Specific Changes in the Fetus and Offspring.

The human selenoproteome is comprised of ~25 genes, which incorporate selenium, in the form of selenocysteine, into their structure. Since it is well known that selenium is important to maternal health and foetal development during pregnancy, this study aimed at defining the impact of selenium deficiency on maternal, placental, foetal and offspring selenoprotein gene expression. Female C57BL/6 mice were randomly allocated to control (>190 μg/kg) or low selenium (<50 μg/kg) diets four weeks prior to mating and throughout gestation. At embryonic day (E)18.5, pregnant mice were sacrificed followed by collection of maternal and foetal tissues. A subset of mice littered down, and offspring were monitored from postnatal day (PN) 8, weaned at PN24 and sacrificed at PN180, followed by tissue collection. Following RNA extraction, the expression of 14 selenoproteins was assessed with qPCR in liver, kidneys, muscle and placenta. Selenium deficiency downregulated expression (Ptrt < 0.05) of many selenoproteins in maternal tissues and the placenta. However, foetal selenoprotein expression was upregulated (Ptrt < 0.05) in all tissues, especially the kidneys. This was not reflected at PN180; however, a sexually dimorphic relationship in selenoprotein expression was observed in offspring. This study demonstrates the selenoproteome is sensitive to dietary selenium levels, which may be exacerbated by pregnancy. We concluded that transcriptional regulation of selenoproteins is complex and multifaceted, with expression exhibiting tissue-, age- and sex-specificities.

Selenium Anticancer Properties and Impact on Cellular Redox Status

(1) Background: In this review, we provide information published in recent years on the chemical forms, main biological functions and especially on antioxidant and prooxidant activities of selenium. The main focus is put on the impact of selenoproteins on maintaining cellular redox balance and anticancerogenic function. Moreover, we summarize data on chemotherapeutic application of redox active selenium compounds. (2) Methods: In the first section, main aspects of metabolism and redox activity of selenium compounds is reviewed. The second outlines multiple biological functions, asserted when selenium is incorporated into the structure of selenoproteins. The final section focuses on anticancer activity of selenium and chemotherapeutic application of redox active selenium compounds as well. (3) Results: optimal dietary level of selenium ensures its proper antioxidant and anticancer activity. We pay special attention to antioxidant activities of selenium compounds, especially selenoproteins, and their importance in antioxidant defence. It is worth noting, that data on selenium anticancer properties is still contraversive. Moreover, selenium compounds as chemotherapeutic agents usually are used at supranutritional doses. (4) Conclusions: Selenium play a vital role for many organism systems due to its incorporation into selenoproteins structure. Selenium possesses antioxidant activity at optimal doses, while at supranutritional doses, it displays prooxidant activity. Redox active selenium compounds can be used for cancer treatment; recently special attention is put to selenium containing nanoparticles.

PSIV-B-36 Late-Breaking: Selenium content and speciation in muscle of pigs fed diets supplemented with different selenium sources and doses

Abstract Selenium (Se) is an essential element for pigs with diet being the major source of intake, while the metabolic process of different sources and doses of dietary Se in pigs muscle remains unclear. In this study, a reliable HPLC-ICP-MS approach was developed for analyzing selenium speciation in the muscle of pigs, which could analyze seven selenium speciation in ten minutes. This approach was used to study the metabolism of different sources and doses of dietary selenium in pigs muscle. In total, 108 castrated male pigs (Duroc × Landrace × Yorkshire, 61.3 ± 3.3 kg) were randomly assigned to six treatment groups with six replicates of three pigs per replicate. These six treatments received the same basal diet (0.1 mg Se/kg) without any Se supplement (BD-0.1), or basal diet supplemented with sodium selenite (0.25 mg Se/kg, SSe-0.25), methylselenocysteine (0.25 mg Se/kg, MeSeCys-0.25), or selenomethionine (0.25, 0.50, and 2.5 mg Se/kg, SeMet-0.25, SeMet-0.5, and SeMet-2.5) for 60 days. At the end of the experiment, six pigs from each group (one pig per replicate) were slaughtered and the longissimus dorsi muscle was collected for total Se and Se speciation analysis. The results showed that the selenium sources deposition efficiency was ranked as: selenomethionine &amp;gt; methylselenocysteine &amp;gt; selenite, and the muscle selenium content had a dose effect with selenomethionine supplementation (Figure 1). Four species of selenium were detected in the muscles of pigs, and the distribution of these selenium species were greatly affected by the dietary selenium supplementation forms and levels (Figure 2). Selenomethionine (&amp;gt; 70% of total selenium) and selenocystine (&amp;gt; 11%) were the major selenium species, followed by methylselenocysteine and selenourea. These findings could be advantageous for rational use of selenium supplements, as well as for selenium-enriched pork production.

PHYSIOLOGICAL RESPONSE OF BROILER CHICKENS UNDER HEAT STRESS CONDITIONS FOR SOME ORGANIC ANTIOXIDANT ADDITIVES.

One hundred and twenty 1-d old commercial broiler chicks (Cobb) were divided in to four groups with six replicats, to investigate the effect of dietary supplementation with organic chromium (Cr), organic selenium (Se) and Vitamin E (Vit.E) on some physiological and immunological parameters. The first group was the control group, while the second group was fed the basal diet supplemented with organic chromium (0.8 mg/kg diet), the third group was fed the basal diet supplemented with organic selenium (0.3 mg/kg diet) and the fourth group was fed the basal diet supplemented with vitamin E (200 IU/kg diet). Temperature and humidity were recorded daily and the Temperature-Humidity Index (THI) was calculated, which demonstrated that birds were exposed to heat stress throughout the experiment period. The results showed that increasing dietary levels of organic chromium, organic selenium and Vitamin E especially Vitamin E supplementation could improve plasma total protein and globulin (p<0.05) values at 42 DOA. Supplements could significantly (p<0.05) enhance the total antibody titer against Newcastle disease Virus (NDV) either for the primary or secondary response and induce higher expression of heat shock protein 70 (HSP 70). Insulin-like Growth factor-I (IGF-I) level was improved significantly (p<0.05) due to increasing dietary organic chromium levels followed by vitamin E than organic selenium. It could be concluded that the dietary addition of organic chromium (Cr), organic selenium (Se) and Vitamin E (Vit.E) triggered improvements in the physiological and immunological measurements of broilers reared under heat stress conditions

EFFECT OF ADDING SOME ORGANIC ANTIOXIDANTS TO BROILER DIETS UNDER HEAT STRESS CONDITIONS

An experiment was conducted to investigate the effects of increasing dietary levels of organic chromium, organic selenium and Vitamin E on heat stressed broilers. A total of 120 1-d old commercial broiler chicks (Cobb) were obtained from a local hatchary. Upon arrival the chicks were divided into four groups with six replications, each of five chicks. The first group was the control group, while the second group was fed the basal diet supplemented with organic chromium (0.8 mg/kg diet), the third group was fed the basal diet supplemented with organic selenium (0.3 mg/kg diet) and the fourth group was fed the basal diet supplemented with vitamin E (200 IU/kg diet).Body weight (BW); body weight gain (BWG); feed intake (FI) and feed conversion ratio (FC) were significantly (P≤0.05) improved in treatment groups compared to the control at 21 and 42 days of the age. Red blood cell count (RBSc), hematocrit (Ht), hemoglobin (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV) and heterophils/lymphocytes ratios (H/l ratio) were significantly (P≤0.05) different in vitamin E; organic selenium and organic chromium compared to the control at 21 and 42 days of the age, but RBSc count at 21 day of age were not significant. Moreover, values of glutathione peroxidase (GPX), Super-oxide dismutase (SOD) and Catalase (CAT) were significantly (P≤0.05) increased but Malondiadehyde (MDA) was significantly (P≤0.05) decreased with supplemental vitamin E; organic selenium and organic Chromium compared with control. Carcass characteristics of supplemented broilers were also improved (P≤0.05) compared to the control. However, abdominal fat, thymus, bursa and spleen were not significantly changed. The present results indicate that dietary supplementation of vitamin E; organic selenium and organic chromium, especially vitamin E, is necessary to overcome the deleterious effects of heat stress on broilers.

Role of Selenoproteins in Bacterial Pathogenesis.

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

Development and application of a HPLC-ICP-MS method to determine selenium speciation in muscle of pigs treated with different selenium supplements

Dietary selenium deficiency is recognized as a global problem. Pork is the most widely consumed meat throughout the world and an important source of selenium for humans. In this study, a reliable approach was developed for analyzing selenium and its speciation in the muscles of pigs after different selenium treatments. The selenium source deposition efficiency was ranked as: selenomethionine > methylselenocysteine > selenite, and the muscle selenium content had a dose effect with selenomethionine supplementation. In total, four species of selenium were detected in the muscles of pigs and the distributions of these selenium species were greatly affected by the dietary selenium supplementation forms and levels. Selenomethionine (>70% of total selenium) and selenocystine (>11%) were the major selenium species, followed by methylselenocysteine and selenourea. Therefore, selenium-enriched pork produced from selenomethionine is a good source for improving human dietary selenium intake.

RNA-Seq Analysis in Liver of Selenium-deficient Selenocysteine Lyase Knockout Mouse (P24-023-19)

ObjectivesSelenium is a trace element critical for appropriate response to oxidative stress in cells. Once ingested, dietary selenium is mostly metabolized by the liver. Selenium is utilized to produce the amino acid selenocysteine, which can be incorporated into selenoproteins, most of them functioning in curbing reactive oxygen species. The enzyme selenocysteine lyase (Scly) decomposes selenocysteine into selenide, and its highest expression and activity occurs in the liver. Disrupting the Scly gene (Scly−/−) resulted in overweight mice with hyperlipidemia, hyperinsulinemia and glucose intolerance, phenotype traits that were aggravated by a selenium-deficient diet. In the liver, Scly−/−mice had lower hepatic selenium levels than their wild-type mice counterparts. Our objective was to identify differentially expressed genes and pathways in Scly−/- mice livers affected by dietary selenium levels. MethodsScly−/- and wild-type mice were fed diets containing 0.08 (mildly low) or 0.25 (adequate) ppm of sodium selenite. We extracted total RNA from livers with a commercial kit. High-quality RNA (RIN ≥ 7) as assessed by a BioAnalyzer was employed in RNA-sequencing. RNA-Seq data analysis was performed on Partek flow software followed by pathway analysis using Ingenuity Pathway Analysis software. Validation of results was pursued by real-time RT-qPCR using specific primer sets. ResultsHepatic RNA-Seq analysis revealed 52 genes differentially regulated by Scly disruption and low dietary selenium levels, encompassing 41 pathways, including PXR/RXR activation, LPS/IL-1-mediated inhibition of RXR function, xenobiotic metabolism signaling, nicotine degradation, adipogenesis, and acyl-CoA hydrolysis. Ten differentially expressed genes were validated by real-time RT-qPCR, including Selenobp2, Eif4ebp3, Mt1, and Mt2. ConclusionsWe identified pathways and validated genes in the Scly−/- mouse liver that are implicated in the metabolic phenotype displayed by this model on a low selenium diet. Funding SourcesThis project was supported by the National Institutes of Health (NIH) grants U54MD007601 Ola Hawaii (subproject 5544), P30-CA071789–128, R01DK47320, and P20GM103466. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Dietary supplementation of selenium yeast enhances the antioxidant capacity and immune response of juvenile Eriocheir Sinensis under nitrite stress

This study elucidates the response to nitrite stress and the effect of dietary selenium supplements on the growth, antioxidant activity, immunity and transcriptome of juvenile Chinese mitten crab Eriocheir sinensis. In the control group, the crabs were fed the diet without selenium supplementation and there was no nitrite addition to the water. In the test group, the crabs were fed diets with three levels of selenium 0 (N1), 0.5 (N2) and 1.0 (N3) mg/kg in the water containing 2 mg/L NO2N as a stress factor for eight weeks. Feed conversion ratio (FCR) was improved by adding dietary selenium. There was no significant difference in specific growth rate and weight gain between N1 and the control groups, or among different selenium levels in the test group. The superoxide dismutase (SOD) activity was significantly lower, but malondialdehyde (MDA) was higher in the N1 group than those in the serum and hepatopancreas of the control group. The activities of SOD, glutathione peroxidase (GPx) and acid phosphatase increased at the medium level of selenium but decreased as the level of dietary selenium increased to 1.0 mg/kg. The serum lysozyme (LZM) activity increased but the MDA content in both serum and hepatopancreas decreased with the increase of selenium levels. The total clean reads of the crabs in the control group, N1 and N3 groups reached 390.7M and were assembled into 106 471 transcripts. Compared with the control group, 1196 gene were significantly expressed (588-up and 608-down) in the N1 group under nitrite stress. Between the N1 and N3 groups, the expression of 1537 genes (751-up and 786-down) were significantly different. KEGG pathway analysis reveals that 11 and 19 pathways were significantly different between N1 and control and between N3 and N1 groups, respectively. Transcriptome results demonstrate that nutrient metabolism is much more active in crabs fed additional selenium under nitrite stress. This study indicates that dietary selenium can improve both antioxidant capacity and immune response and alter the protein and carbohydrate metabolism of E. sinensis under nitrite stress.

Effect of dietary organic selenium on survival, growth, antioxidation, immunity and gene expressions of selenoproteins in abalone Haliotis discus hannai

No studies have been focused on the inclusion of organic selenium in formulated feed of abalone when organic minerals are accepted by aquaculture feed industry. This experiment evaluated the effect of organic selenium on the growth, antioxidation, immunity and gene expressions of selenoproteins in abalone. Graded levels of organic selenium were included to the basal diet at 0.00, 0.15, 0.30 and 0.60 ppm providing 157.83, 322.51, 437.59 and 596.59 ug/kg of selenium in the diet. Accordingly, the diets were named as Se-0.00, Se-0.15, Se-0.30 and Se-0.60 respectively. Results had shown that survival rate, weight gain rate and shell length increase rate were lowest for Se-0.60 group (p < 0.05). The concentration of selenium in the whole body generally increased with increasing level of dietary organic selenium (p < 0.05). The enzyme activities related to antioxidation increased initially with low levels of dietary selenium and decreased with higher levels, with the highest value in Se-0.30 group (p < 0.05). The enzyme activities of immunity increased with the addition of dietary selenium. With the increase of dietary selenium, Myostain expression decreased initially and increased afterwards, with lowest value for Se-0.30 group (p < 0.05). However, the expressions of other genes related to growth, antioxidation and selenoproteins firstly increased and then decreased, with the highest value recorded for Se-0.15 group. In conclusion, the inclusion rate of 0.15 – 0.30 ppm Se in diet could promote growth, antioxidation, immunity and gene expressions of selenoproteins in abalone; however, excess selenium with 0.60 ppm inclusion lever in diet had toxic effects.