Influence of Different Amounts and Sources of Selenium Supplementation on Performance, Some Blood Parameters, and Nutrient Digestibility in Lambs

Two trials were conducted in a 2?×?2?+?1 factorial arrangement based on a completely randomized design to evaluate the effects of different sources of selenium (Se) on performance, blood metabolites, and nutrient digestibility in male lambs on a barley-based diet. The first trial lasted for 70 days and consisted of 30 lambs (35.6?±?2.6 kg mean body weight, about 4–5 months of age) which were randomly allotted to five treatments including: (1) basal diet (containing 0.06 mg Se/kg DM; control) without supplementary Se, (2) basal diet?+?0.20 mg/kg Se as sodium selenite (SeS 0.20), (3) basal diet?+?0.40 mg/kg Se as sodium selenite (SeS 0.40), (4) basal diet?+?0.20 mg/kg Se as selenium yeast (SeY 0.20), and (5) basal diet?+?0.40 mg/kg Se as selenium yeast (SeY 0.40). For the second trial, four lambs from each group of experiment 1 were randomly allocated to individual metabolic cages for 14 days to measure the effects of dietary Se on nutrient digestibility. The results revealed that there were no significant differences for average daily gain, average daily feed intake, feed/gain ratio, hematological parameters (packed cell volume, red blood cell, white blood cell, and hemoglobin values), serum total protein, albumin, globulin, aspartate amino transferase, alkaline phosphatase, and creatine phosphokinase due to supplementation of different amounts and sources of Se in lambs. Dietary Se supplementation significantly improved (P?<?0.001) glutathione peroxidase activity in blood. Furthermore, at the end of the trial, serum tri-iodothyronine (T3) amount also increased (P?<?0.05), while serum thyroxine (T4) amount decreased (P?<?0.05). Digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber increased (P?<?0.05) by Se yeast supplementation. It may be concluded that supplementation of Se in lambs had no significant effect on performance and blood hematology, but increased blood glutathione peroxidase activity and serum T3 amount and decreased serum T4 amount as compared to non-supplemented control lambs. Furthermore, Se yeast improved nutrient digestibility in lambs.     

Effect of epigallocatechin gallate on growth performance and antioxidant capacity in heat-stressed broilers

This study investigated the effects of epigallocatechin gallate (EGCG) on the growth performance and antioxidant capacity of 35-d-old broilers exposed to heat stress. Broilers, 14 d of age, were divided into four groups with six replicates per group (eight chickens/replicate). Thermoneutral group (Group TN) was fed the basal diet and maintained at 28°C for 24 h/d. The heat-stressed groups were housed at 35°C for 12 h/d and 28°C for 12 h/d and fed the basal diet supplemented with EGCG at 0, 300 and 600 mg/kg diet (Groups HS0, HS 300 and HS600, respectively). Compared with Group TN, heat-stressed groups showed significantly reduced gain, feed intake and serum total protein and glucose levels; inhibited serum alkaline phosphatase activities; and increased serum levels of uric acid, cholesterol and triglycerides and the activity of serum creatine kinase, lactate dehydrogenase and aspartate aminotransferase (p < 0.05). Compared with Group HS0, Group HS600 exhibited an increased gain and feed intake; and normalised blood parameters and enzyme activities. Compared with Group TN, the expression of antioxidant-related liver proteins was decreased in Group HS0 and increased in Groups HS300 and HS600 (p < 0.05). The results suggest that EGCG can improve the growth performance and alleviate the oxidant damage by modulating the antioxidant properties of broilers.     

The effect of dietary methionine levels on fattening performance and selected blood and tissue parameters of turkeys

A total of 490 eight-week-old female Hybrid Converter turkeys (body weight 4.11 ± 0.03 kg) were divided into 5 groups with 7 replicates of 14 birds each. For 8 weeks, basal diets were supplemented with methionine (Met) at following levels (weeks 9–12/weeks 13–16 of age): Group 1 – 0.34/0.29%, Group 2 – 0.39/0.34%, Groups 3 and 4 – 0.45/0.38% and 0.51/0.41%, respectively, Group 5 – 0.58/0.47%. Only in the first feeding phase the body weight gain (BWG) was affected by Met levels with the significantly highest BWG in Group 3. No treatment effects were found for feed conversion ratio, carcass yield, carcass composition and meat colour. The blood superoxide dismutase activity was significantly highest in Groups 2 and 3. The concentrations of reduced glutathione in the liver were linearly increased (p = 0.018), whereas the ratio of reduced glutathione to oxidised glutathione was highest in Group 3 (quadratic contrast, p = 0.004). It can be concluded that turkeys from Group 3 (Met levels age depending 15% and 10% above recommendations by NRC) were characterised by a well-balanced physiological response. Attention should be paid to the immune response of birds to higher dietary Met levels: plasma IgA concentrations decreased, whereas IL-6 and TNF-α levels increased in turkeys fed diets with the highest Met content.     

Selenium and Glutathione Peroxidase Levels in Lambs Receiving Feed Supplemented with Sodium Selenite or Selenomethionine

Twenty-one 6 months old female lambs were divided into 7 groups and fed a basal diet containing 0.13 mg Se/kg. The basal diet was further supplemented with 0, 0.1, 0.5 or 1.0 mg Se/kg either as sodium selenite or as selenomethionine, and was fed for 10 weeks. Both feed additives produced an increase in the selenium concentration in the tissues analysed. Significant correlations were found between the concentrations of selenomethionine or sodium selenite added to the feed and the subsequent tissue levels. However, the selenium levels seemed to plateau at approximately 0.5 mg Se/kg of supplemented sodium selenite. The total glutathione peroxidase (GSH-Px) activity of the tissues increased when the selenium supplementation increased from 0 to 0.1 mg/kg for both selenium compounds. With further increase in selenium supplementation the GSH-Px activity in the tissues plateaued except in the blood where the activity continued to rise with increasing selenomethionine supplementation. The selenium dependent GSH-Px activity in the liver rose with increasing selenomethionine supplementation, but approached a plateau when 0.1 mg Se/kg as sodium selenite was added to the feed. The selenium concentration in whole blood responded more rapidly to the selenium supplementation than did GSH-Px activity. The experiment indicates that the optimal selenium concentration in the feed is considerably higher than 0.1 mg Se/kg, and that selenium levels of 1.0 mg/kg in the feed do not result in any risk for the animals or the consumers of the products.     

Effects of Selenium- and Chromium-Enriched Diets on Growth Performance,Lipid Profile,and Mineral Concentration in Different Tissues of Growing Rabbits

The aim of this study was to investigate the effect of dietary supplementation with different sources of selenium and/or organic chromium on the growth performance, digestibility, lipid profile, and mineral content of hair, liver, and fore and hind limb of growing rabbits. A total of 150 weanling New Zealand White (NZW) male rabbits were randomly allotted to six dietary treatment groups: (1) basal diet (control group), (2) basal diet + 0.6 mg sodium selenite/kg diet, (3) basal diet + 0.6 mg selenium yeast/kg diet, (4) basal diet + 0.3 mg sodium selenite/kg diet + 0.3 mg selenium yeast/kg diet, (5) basal diet + 0.6 mg chromium yeast/kg diet + 0.6 mg selenium yeast/kg diet, (6) basal diet + 0.6 mg chromium yeast/kg diet. Only the combination between inorganic and organic selenium led to significant improvement in body weight, body weight gain, and feed conversion ratio. Carcass traits were not different in all groups. Selenium (Se) and chromium (Cr) were deposited in the tissues of rabbits fed diets supplemented with Se and Cr, respectively. Blood serum in both of selenium- and chromium-supplemented groups showed declined total cholesterol, triglycerides, and low-density lipoprotein (LDL). Group supplemented with organic chromium showed higher high-density lipoprotein (HDL) than the other groups. It could be concluded that using a mixture of inorganic and organic Se has a positive effect on the growth performance of growing rabbits. Both Se and Cr have hypocholesterolemic effect. Both of Se and Cr can be deposited in the meat and other tissues of rabbits and that improves meat quality which positively reflects on human acceptance. The combination between inorganic (0.3 mg sodium selenite/kg diet) and organic selenium (0.6 mg selenium yeast/kg diet) improved growth performance traits of growing rabbits.

     

Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance,immune status and anti-oxidative capacity in early weaned piglets

The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses.     

Ameliorative Effects of Selenium on Cadmium-Induced Injury in the Chicken Ovary: Mechanisms of Oxidative Stress and Endoplasmic Reticulum Stress in Cadmium-Induced Apoptosis

Despite the well-established toxicity of cadmium (Cd) to animals and the ameliorative effects of selenium (Se), some specific mechanisms in the chicken ovary are not yet clarified. To explore the mechanism by which the toxicity effect of Cd is induced and explore the effect of supranutritional Se on Cd toxicity in female bird reproduction, forty-eight 50-day-old Isa Brown female chickens were divided randomly into four groups. Group I (control group) was fed the basic diet containing 0.2 mg/kg Se. Group II (Se-treated group) was fed the basic diet supplemented with sodium selenite (Na₂SeO₃), and the total Se content was 2 mg/kg. Group III (Se + Cd-treated group) was fed the basic diet supplemented with Na₂SeO₃; the total Se content was 2 mg/kg, and it was supplemented with 150 mg/kg cadmium chloride (CdCl₂). Group IV (Cd-treated group) was with the basic diet supplemented with 150 mg/kg CdCl₂. The Cd, estradiol (E2), and progestogen (P4) contents changed after subchronic Cd exposure in chicken ovarian tissue; subsequently, oxidative stress occurred and activated the endoplasmic reticulum (ER) pathway to induce apoptosis. Further, Se decreased the accumulation of Cd in ovarian tissue, increased the E2 and P4 contents, alleviated oxidative stress, and reduced apoptosis via the ER stress pathway. The present results demonstrated that Cd could induce apoptosis via the ER stress pathway in chicken ovarian tissue and that Se had a significant antagonistic effect. These results are potentially valuable for finding a strategy to prevent Cd poisoning.     

Supplemented Organic and Inorganic Selenium Affects Milk Performance and Selenium Concentration in Milk and Tissues in the Guanzhong Dairy Goat

Trace amounts of selenium (Se) are essential for several organisms, and deficiencies therein have adverse effects on growth, development, and reproduction; this is particularly significant in animals raised for milk and livestock production. To study the effect of Se on Guanzhong dairy goats, their diets were supplemented with different sources (inorganic or organic) and Se concentrations (0.2 or 0.4 mg Se/kg). A non-Se-fortified basal diet served as a negative control, and a sixth treatment group received both inorganic and organic Se sources (0.2 mg Se/kg diet each). Dietary Se supplementation increased milk production, with organic Se being more effective than inorganic Se. Selenium supplementation also increased Se concentration and glutathione peroxidase activity in whole blood, with organic Se more effective than inorganic Se at the same Se concentration. With increasing Se in diets, the Se content in milk increased markedly, reaching a plateau value at day 30 in all groups, and organic Se (0.4 mg/kg diet) had the best effect. In addition, dietary Se sources and concentrations markedly affected Se concentrations in different tissues and organs. Thus, organic Se supplementation of a basal diet at 0.4 mg/kg is practically applicable for Se-enriched milk and meat production in Guanzhong dairy goats.     

Effects of Zinc Glycinate on Productive and Reproductive Performance,Zinc Concentration and Antioxidant Status in Broiler Breeders

An experiment was conducted to investigate the effects of zinc glycinate (Zn-Gly) supplementation as an alternative for zinc sulphate (ZnSO₄) on productive and reproductive performance, zinc (Zn) concentration and antioxidant status in broiler breeders. Six hundred 39-week-old Lingnan Yellow broiler breeders were randomly assigned to 6 groups consisting of 4 replicates with 25 birds each. Breeders were fed a basal diet (control group, 24 mg Zn/kg diet), basal diet supplemented with 80 mg Zn/kg diet from ZnSO₄ or basal diet supplemented with 20, 40, 60 and 80 mg Zn/kg diet from Zn-Gly. The experiment lasted for 8 weeks after a 4-week pre-test with the basal diet, respectively. Results showed that Zn supplementation, regardless of sources, improved (P?<?0.05) the feed conversion ratio (kilogram of feed/kilogram of egg) and decreased broken egg rate, and elevated (P?<?0.05) the qualified chick rate. Compared with the ZnSO₄ group, the 80 mg Zn/kg Zn-Gly group significantly increased (P?<?0.05) average egg weight, fertility, hatchability and qualified chick rate, whereas it decreased (P?<?0.05) broken egg rate. The Zn concentrations in liver and muscle were significantly higher (P?<?0.05) in 80 mg Zn/kg Zn-Gly group than that in ZnSO₄ group. Compared with ZnSO₄ group, 80 mg Zn/kg Zn-Gly group significantly elevated (P?<?0.05) the mRNA abundances of metallothionein (MT) and copper-zinc superoxide (Cu-Zn SOD), as well as the Cu-Zn SOD activity and MT concentration in liver. Moreover, the 80 mg Zn/kg Zn-Gly group had higher (P?<?0.05) serum T-SOD and Cu-Zn SOD activities than that in the ZnSO₄ group. This study indicated that supplementation of Zn in basal diet improved productive and reproductive performance, Zn concentration and antioxidant status in broiler breeders, and the 80 mg Zn/kg from Zn-Gly was the optimum choice for broiler breeders compared with other levels of Zn from Zn-Gly and 80 mg/kg Zn from ZnSO₄.     

Alleviation Mechanisms of Selenium on Cadmium-Spiked Neutrophil Injury to Chicken

To determine the negative effects of cadmium (Cd) exposure and the protective role of selenium (Se) on Cd-spiked neutrophils of chicken, forty-eight 28-day-old Isa Brown male chickens were divided randomly into four groups. Group I (control group) was fed with the basic diet containing 0.2 mg/kg Se. Group II (Se-treated group) was fed with the basic diet supplemented with Na₂SeO₃, and the total Se content was 2 mg/kg. Group III (Se/Cd-treated group) was fed with the basic diet supplemented with Na₂SeO₃; the total Se content was 2 mg/kg and supplemented with 150 mg/kg CdCl₂. Group IV (Cd-treated group) was fed with the basic diet supplemented with 150 mg/kg CdCl₂. Analyses of inflammatory factors, cytokines, and heat shock protein (Hsp) messenger RNA (mRNA) expression were detected by real-time PCR (RT-PCR). Additionally, we evaluated the phagocytic rate of neutrophils in peripheral blood. First, we observed that Cd significantly induced the mRNA expression levels of inflammatory factors NF-κB, iNOS, COX-2, and TNF-α, while Se/Cd treatment reduced their mRNA expression, although these expression levels remained higher than that of the control group. In addition, the mRNA expression levels of cytokines (IL-2, IL-4, and IL-10) for the Se-treated group exhibited significant differences between the Se/Cd-treated group and the Cd-treated group. Furthermore, the mRNA expression levels of Hsps demonstrated that the Se/Cd-treated group and the Cd-treated group were significantly higher (P < 0.05) than the control group and the Se-treated group. These results demonstrated that Se presented partial protection on Cd-spiked neutrophils of chicken with Hsps being involved in the process of the Cd-spiked toxic effects in chicken peripheral blood neutrophils.     

Role of Selenium from Different Sources in Prevention of Pulmonary Arterial Hypertension Syndrome in Broiler Chickens

Pulmonary arterial hypertension (PAH) syndrome in broilers is associated with hypoxia, which prevails at high altitude. Oxidative stress is the pathogenic mechanism underlying PAH. Because selenium is key element in the structure of antioxidant enzymes, we evaluated pulmonary hypertensive responses in broiler chickens fed with diets supplemented with organic or nano-selenium. One hundred forty-four broilers (starting at 5 days old) were fed with (i) control group: birds received a standard diet; (ii) nano-selenium group: birds were fed with basal diet supplemented with nano-selenium at 0.3 mg/kg; and (iii) organic selenium group: birds received basal diet supplemented with organic selenium at 0.3 mg/kg. We assessed growth performance, carcass characteristics, antioxidant variables, blood parameters, and small intestine morphology. Although Se supplementation did not affect growth performance, carcass traits, and organ weight (P > 0.05), the right to total ventricular weight ratio (RV:TV), malondialdehyde concentration in the liver, and heterophil to lymphocyte ratio were significantly lower in the nano-selenium group relative to the control (P < 0.05). Chickens that received nano-selenium also elicited significantly higher antibody titers after 24 h of an injection of sheep red blood cells (P < 0.05). Nano-selenium supplementation also significantly increased villus height, absorptive surface area, and lamina propria thickness relative to the control (P < 0.05) in different segments of the small intestine. In contrast, organic selenium supplement improved intestinal morphometry only in the jejunum. We conclude that dietary supplementation of 0.30 mg/kg nano-selenium could prevent right ventricular hypertrophy as reflected by reduced RV:TV, reduced levels of lipid peroxidation in the liver, and improved gut function.     

Parameters of dietary selenium and vitamin E deficiency in growing rabbits.

4 x 5 growing female rabbits (New Zealand White) with an initial live weight of 610 +/- 62 g were fed a torula yeast based semisynthetic diet low in selenium (<0.03 mg/kg diet) and containing <2 mg alpha-tocopherol per kg (group I). Group II received a vitamin E supplementation of 150 mg alpha-tocopherylacetate per kg diet, whereas for group III 0.40 mg Se as Na-selenite and for group IV both supplements were added. Selenium status and parameters of tissue damage were analyzed after 10 weeks on experiment (live weight 2,355 +/- 145 g). Selenium depletion of the Se deficient rabbits (groups I and II) was indicated by a significantly lower plasma Se content (group I: 38.3 +/- 6.23 microg Se/mL plasma, group II: 42.6 +/- 9.77, group III: 149 +/- 33.4, group IV: 126 +/- 6.45) and a significantly lower liver Se content (group I: 89.4 +/- 18.2 microg/kg fresh matter, group II: 111 +/- 26.2) as compared to the Se supplemented groups III (983 +/- 204) and IV (926 +/- 73.9). After 5 weeks on the experimental diets differences in the development of plasma glutathione peroxidase were observed. As compared to the initial status group (45.2 +/- 4.50) pGPx activity in mU/mg protein was decreased in group I (19.1 +/- 7.08), remained almost stable in the vitamin E supplemented group II (46.3 +/- 11.2) whereas an elevated enzyme activity was measured in the Se supplemented groups III (62.4 +/- 23.9) and IV (106 +/- 19.9). In the rabbit organs investigated 10 weeks of Se deficiency caused a significant loss of Se dependent cellular glutathione peroxidase activity (GPx1) of 94% (liver), 80% (kidney), 50% (heart muscle) and 60% (musculus longissimus dorsi) in comparison to Se supplemented control animals. Damage of cellular lipids and proteins in the liver was due to either Se or vitamin E deficiency. However damage was most severe under conditions of a combined Se and vitamin E deficiency. It can be concluded that the activity of plasma glutathione peroxidase is a sensitive indicator of Se deficiency in rabbits. The loss of GPx1 activity indicates the selenium depletion in various rabbit organs. Both selenium and vitamin E are essential and highly efficient antioxidants which protect rabbits against lipid and protein oxidation.     

Effects of Dietary Form of Selenium on Its Distribution in Eggs

The objective of this experiment was to investigate the selenium distribution in eggs from hens fed diets supplemented with Se from sodium selenite (SS) or selenium-enriched yeast (SY). One-day-old female chickens of Hy-Line Brown breed were randomly divided into four groups according to dietary treatments and, for the subsequent 9?months, were fed diets which differed only in the form or amount of Se supplemented. During the whole experiment, group 1 (control) was fed basal diet (BD) with only background Se level of 0.13?mg/kg dry matter (DM). Diets for groups 2 and 3 consisted of BD supplemented with an Se dose of 0.4?mg/kg DM either in the form of SS or SY, respectively. Group 4 was fed BD supplemented with 0.9?mg Se/kg DM from SY. After 9?months of dietary treatments, the Se levels in egg yolk and albumen from hens fed unsupplemented diet were almost identical whereas eggs from hens given diet supplemented with SS showed significantly higher Se deposition in yolk than in albumen (P?相似文献   

Effects of Montmorillonite on Alleviating Dietary Cd-Induced Oxidative Damage in Carp (Carassius auratus)

The present study was designed to investigate the effects of montmorillonite (MMT) on dietary Cd-induced oxidative damage in liver and kidney of carp (Carassius auratus). One hundred eighty carp were randomly divided into four groups and fed with a basal diet, a basal diet supplemented with 0.5% MMT, Cd-comtaminated basal diet (120 mg Cd/kg dry weight) and Cd-contaminated basal diet supplemented with 0.5% MMT, respectively. After 60 days, fish were sacrificed to measure malondialdehyde (MDA) content and antioxidative indices in liver and kidney. The results showed that the exposure of carp to dietary Cd caused decreases in glutathione peroxidase activity, catalase activity, superoxide dismutase activity, glutathione content and total antioxidant capacity level, while MMT supplemented in diet compensated Cd-induced decreases in above antioxidant indices to some extent in liver and kidney. As compared with the control group, increases in MDA content were observed in both measured tissues of carp exposed to dietary Cd, while MDA content decreased in carp exposed to Cd-contaminated basal diet supplemented with MMT in comparison with the Cd-contaminated group. It was suggested that MMT, when co-administered with Cd in diet, could alleviate dietary Cd-induced oxidative damage in liver and kidney of carp.     

The potential effects of antioxidant feed additives in mitigating the adverse effects of corn naturally contaminated with <Emphasis Type="Italic">Fusarium</Emphasis> mycotoxins on antioxidant systems in the intestinal mucosa,plasma, and liver in weaned pigs

Seventy-two piglets (6.0 kg BW) were randomly distributed within six different dietary treatments to evaluate the effect of deoxynivalenol (DON) and the potential of four antioxidant feed additives in mitigating the adverse effects of DON on growth performances and oxidative status. Dietary treatments were as follows: control diet 0.8 mg/kg DON; contaminated diet (DON-contaminated diet) 3.1 mg/kg DON; and four contaminated diets, each supplemented with a different antioxidant feed additive, DON + vitamins, DON + organic selenium (Se)/glutathione (GSH), DON + quercetin, and DON + COMB (vitamins + Se/GSH + quercetin from the other treatments). Although DON was the main mycotoxin in the contaminated diet, this diet also contained 1.8 mg/kg of zearalenone (ZEN). The “mycotoxin” effects therefore included the combined effect of these two mycotoxins, DON, and ZEN. The DON-ZEN ingestion did not affect growth performances, average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F ratio), but partially induced oxidative stress in weaned pigs as shown by increased malondialdehyde (MDA) content in the plasma and superoxide dismutase (SOD) activity in liver (P?<?0.05). However, no change in the activity of other antioxidant enzymes or GSH concentrations was observed in plasma and liver of piglets fed the DON-contaminated diet (P?>?0.05). Supplementation with individual antioxidant feed additive had a limited effect in weaned pigs fed DON-ZEN-contaminated diets. Combination of antioxidants (vitamins A, C, and E, quercetin, and organic Se/GSH) reduced plasma and liver MDA content and SOD activity in liver (P?<?0.05) of piglets fed DON-ZEN-contaminated diets. Furthermore, this combination also reduced MDA content in the ileum (P?<?0.05), although activity of glutathione peroxidases (GPx), SOD or catalase (CAT) in the ileum was not affected by DON-ZEN contamination or antioxidant supplements. In conclusion, DON-ZEN contamination induced oxidative stress in weaned pigs and combination of antioxidant feed additives restored partially the oxidative status. Further studies will be necessary to assess whether the effects of antioxidant feed additives on oxidative status are specific when feed is contaminated with DON-ZEN.     

Effects of different levels of selenium on growth performance and immunocompetence of broilers under heat stress

An experiment was undertaken to evaluate the effect of dietary selenium (Se) levels on growth performance and immune competence of broilers under heat stress. Birds were raised in either a thermoneutral (TN, 23.9°C constant) or heat stress conditions (HS, 23.9°C to 38°C cycling) and were fed a corn-soybean meal basal diet supplemented with Se at 0, 0.2 and 0.4 mg/kg. A total of 240 one-day-old male broiler chicks were randomly assigned to six groups; each group had four replicates of 10 birds. Body weight and feed intake were not influenced by dietary Se, while feed conversion was significantly improved by a Se-supplementation of 0.2 mg/kg. HS significantly reduced body weight, feed intake and feed conversion. Numbers of abdominal exudate cells (AEC), percentage of macrophages in AEC, phagocytic macrophages, internalized opsonised and unopsonised sheep red blood cells (SRBC) were significantly increased by dietary Se. Both primary and secondary antibody responses were characterised by increasing titres of antibody to SRBC by dietary Se when birds were exposed to HS (p < 0.05). Lymphoid organ weights, antibody responses, incidence of macrophages in AEC, and phagocytic ability of macrophages were also significantly reduced under HS. These results indicated that HS severely reduced growth performance and immunocompetence of broilers, whereas the immune response of broilers improved by dietary Se supplementation under HS.     

Effects of Selenium Source and Level on Growth Performance, Tissue Selenium Concentrations, Antioxidation, and Immune Functions of Heat-Stressed Broilers

An experiment is conducted to investigate the effects of selenium (Se) source and level on growth performance, tissue Se concentrations, antioxidation, and immune functions of heat-stressed broilers from 22 to 42?days of age. A total of 210 22-day-old Arbor Acres commercial male chicks were assigned by body weight to one of seven treatments with six replicates of five birds each in a completely randomized design involving a 3?×?2 factorial arrangement plus one Se-unsupplemented basal diet control (containing 0.027?mg of Se/kg). The three Se sources were sodium selenite (Na₂SeO₃), Se yeast, and AMMS Se (Se protein), and the two supplemental Se levels were 0.15 or 0.30?mg Se/kg. All birds were reared under heat-stressed condition (33?±?1?°C during 0900?C1700?hours and 27?±?1?°C during 1900?C0700?hours with a relative humidity of 60?C80?%). The results showed that heat-stressed chicks fed Se-supplemented diets had higher (P?<?0.10) average daily feed intake, Se concentrations in liver and breast muscle, liver glutathione peroxidase (GSH-Px) activity, serum antibody titers against H5N1(Re-4 strain), H5N1(Re-5 strain) and lower (P?<?0.01) mortality compared with the control. Chicks fed the diets supplemented with 0.30?mg/kg of Se had higher (P?<?0.05) Se concentrations in liver and breast muscle, liver GSH-Px activity, and serum antibody titer against H5N1 (Re-4 strain) than those fed the diets supplemented with 0.15?mg/kg of Se. Broilers fed the diets supplemented with Se yeast had higher (P?<?0.001) Se concentrations in liver and breast muscle than those fed the diets supplemented with Na₂SeO₃ or AMMS Se. However, broilers fed the diets supplemented with AMMS Se had higher (P?<?0.05) serum antibody titers against H5N1 (Re-4 strain) and H5N1 (Re-5 strain) than those fed the diets supplemented with Na₂SeO₃. These results indicated that Se yeast was more effective than Na₂SeO₃ or AMMS Se in increasing tissue Se retention; however, AMMS Se was more effective than Na₂SeO₃ or Se yeast in improving immune functions of heat-stressed broilers.     

Effects of Dietary Selenium Deficiency or Excess on Gene Expression of Selenoprotein N in Chicken Muscle Tissues

Previous studies have determined the effects of dietary selenium (Se) supplementation on selenoprotein N (SelN, SEPN1), selenophosphate synthetase-1 (SPS1), and selenocysteine-synthase (SecS) mRNA abundance in chicken skeletal and cardiac muscles. To investigate collective responses of these genes to dietary Se concentrations ranging from deficiency to moderately high level in muscle tissues of chicken, 1-day-old chickens were exposed to a diet of deficient Se and supplemented with Se (0.15 mg Se/kg and 1.50 mg Se/kg) as sodium selenite in the feed for 35 days. Muscle tissues (flight, breast, leg, and cardiac muscles) were collected and examined for Se content and mRNA levels of SelN on days 1, 15, 25, and 35 days, respectively. Moreover, SPS1 and SecS mRNA levels were analyzed. The results showed that the expression of SelN gene in cardiac muscle responded to dietary Se concentrations. SelN gene was downregulated in the Se deficiency group (L group), and upregulated in the Se excess group (H group) compared with the moderate Se group (M group) (P?<?0.05) in cardiac muscle. Se deficiency mainly unregulated SelN mRNA level in skeletal muscles compared with M group. Excess dietary Se mainly resulted in the upregulation of SelN mRNA level in skeletal muscles compared with the M group. SecS mRNA levels responded to dietary Se concentrations showed a similar change compared with SelN in cardiac muscle. SPS1 mRNA levels responded to dietary Se concentrations showed a downregulation in L group and upregulation in H group. However, SelN mRNA levels displayed a different expression pattern in different skeletal and cardiac muscles. Moreover, Se also regulated the levels of SPS1 and SecS mRNAs. In summary, Se regulated the expression of SelN gene and affected the mRNA levels of SecS and SPS1. The level of Se in the feed may regulate SelN biosynthesis by affecting the levels of SPS1 and SecS mRNA.     

Selenium Deposition in Tissues and Eggs of Laying Hens Given Surplus of Selenium as Selenomethionine

Forty-eight Norwegian bred White Leghorn chickens were divided into 6 groups and fed a basal diet containing 0.30 mig Se/kg supplemented with 0, 0.1, 0.5, 1.0, 3.0 or 6.0 mg Se/ kg in the form of selenomethionine for 18 weeks. A supplement of only 0.1 mg Se/kg induced significantly higher selenium concentrations in breast muscle and eggs, particularly in the egg white. The increase of selenium in the tissue and egg was proportional to the amounts of selenomethionine added to the feed. In the group given 6.0 mg Se/kg, the selenium concentrations in all tissues and eggs analysed ranged from 4.8 to 7.3 μg Se/g. No signs of toxic effects were observed even at the highest intake of selenium. Excess supply of selenium as selenomethionine to chickens was shown to be more potent than sodium selenite in raising the selenium concentration in tissues and eggs. A supplementation up to 10 times the requirement did not increase the levels of selenium in poultry products to such a degree that they could be considered as a potential risk for human consumption.     

The chemical form of selenium affects insulinomimetic properties of the trace element: investigations in type II diabetic dbdb mice

The objective of the present study was to investigate the effects of oral selenate application in comparison to selenium deficiency and selenite treatment on the development of the diabetic status (glucose tolerance, insulin resistance and activities of glycolytic and gluconeogenic marker enzymes) in dbdb mice, representing a type II diabetic animal model. Therefore 21 adult male dbdb mice were assigned to 3 experimental groups of 7 animals each and put on a selenium deficient diet (< 0.03 mg/kg diet) based on torula yeast. Group 0Se was kept on selenium deficiency for 10 weeks while the mice of the groups SeIV and SeVI were supplemented daily with 15% of their individual LD(50) of sodium selenite or sodium selenate in addition to the diet. After 10 weeks a distinct melioration of the diabetic status indicated by a corrected glucose tolerance and a lowered insulin resistance was measured in selenate treated mice (group SeVI) in comparison to their selenium deficient and selenite treated companions and to their initial status. Activities of the glycolytic marker enzymes hexokinase, phosphofructokinase and pyruvate kinase were increased 1.7 to 3-fold in liver and/or adipose tissue by selenate treatment as compared to mice on selenium deficiency and mice with selenite administration. In contrast selenate treatment (SeVI) repressed the activity of liver pyruvate carboxylase the first enzyme in gluconeogenesis by about 33% in comparison to the selenium deficient (0Se) and selenite treated mice (SeIV). However the current study revealed an insulinomimetic role for selenate (selenium VI) also in type II diabetic animals due to a melioration of insulin resistance. In contrast selenium deficiency and especially selenite (selenium IV) impaired the diabetic status of dbdb mice, demonstrating the need for investigations on the insulinomimetic action of selenium due to the metabolism of different selenium compounds.