Dietary Zinc Levels Research Articles

Dietary zinc and the control of Streptococcus pneumoniae infection

Human zinc deficiency increases susceptibility to bacterial infection. Although zinc supplementation therapies can reduce the impact of disease, the molecular basis for protection remains unclear. Streptococcus pneumoniae is a major cause of bacterial pneumonia, which is prevalent in regions of zinc deficiency. We report that dietary zinc levels dictate the outcome of S. pneumoniae infection in a murine model. Dietary zinc restriction impacts murine tissue zinc levels with distribution post-infection altered, and S. pneumoniae virulence and infection enhanced. Although the activation and infiltration of murine phagocytic cells was not affected by zinc restriction, their efficacy of bacterial control was compromised. S. pneumoniae was shown to be highly sensitive to zinc intoxication, with this process impaired in zinc restricted mice and isolated phagocytic cells. Collectively, these data show how dietary zinc deficiency increases sensitivity to S. pneumoniae infection while revealing a role for zinc as a component of host antimicrobial defences.

The effect of high levels of dietary zinc on growth performance, carcass characteristics, blood parameters, immune response and tissue minerals in growing Boer-cross goat kids

An experiment was conducted to determine animal performance, carcass traits, blood metabolites, immune responses, and tissue minerals in goats fed high levels of zinc (Zn). Twenty-one Boer-cross (Capra aegagrus hircus) growing goat kids (BW, 22.9 ± 1.4 kg, 4–5 months old) were housed individually and fed twice a day 80:20 grain mix: bermudagrass hay (BGH) diet ad libitum for 86 days. Goats in control group (0Zn) received orally 5 mL of water (1.95 + 0.03 ppm Zinc) with no added Zn. Treatment groups, 100Zn and 200Zn received 5 mL water containing additional 100 or 200 mg Zn as Zn sulfate heptahydrate, respectively. Average daily gain (ADG), DM intake, feed conversion ratio (gain: feed), carcass traits, majority of blood attributes and metabolites, and humoral immunity were similar among the treatment groups. However, cell-mediated immune response was higher for 100Zn group (quadratic; P = 0.04). Goats receiving high levels of Zn increased serum calcium (linear; P = 0.03), glucose (linear, P = 0.02), and lymphocytes (linear, P = 0.05 and quadratic; P = 0.01). Manganese (Mn) level in the liver increased (linear, P = 0.01), while liver copper (Cu) decreased (linear, P = 0.04) as the level of Zn was increased in the diet. Zinc in the feces increased (linear, P = 0.001), with no changes in urine Zn. Blood mineral phosphorus was reduced (linear, P = 0.03), and magnesium, and potassium tended to decrease (linear, P = 0.06 and 0.07, respectively) with increasing Zn levels in diet. High levels of Zn supplementation did not affect animal performance and carcass characteristics; however, improved immunity and impacted liver Mn and Cu.

Zinc supplementation modulates T helper 17 cells via the gut microbiome

Abstract Zinc is a dietary micronutrient that regulates various biological processes. Zinc is important for replication and survival of microbes and, as a result, a common strategy of the immune system is to steal zinc away from disease-causing microbes to prevent their growth. Recent studies show that changes in levels of dietary zinc can alter the composition of the gut microbiota, however how this impacts mucosal immune responses in the gut is not known. Here, we show that supplementing mice with zinc sulphate, a commonly used therapy for treating diarrheal episodes, in drinking water for a week resulted in significant changes in gut microbial composition as well drastic reduction in microbial diversity. More importantly. we saw that zinc supplementation attenuated the T helper17 cell number and activity in murine small intestine. To determine if zinc-dependent changes in gut microbiota are sufficient to limit Th17 response, we transplanted the microbiome from zinc treated mice into germ-free mice. We saw that germ-free mice that received cecal contents from zinc treated mice have reduced Th17 response, thus establishing that dietary zinc changes immune potential of the gut microbiome. Th17 cells mediate antimicrobial response in the gut and are involved in the pathogenesis of many autoimmune diseases. Our work thus provides a novel nutritional approach for remodeling microbiota to dampen inflammatory immune responses in the gut.

Dietary zinc requirement of fingerling Indian major carp, Labeo rohita (Hamilton)

The current investigation was carried out to estimate the requirement of dietary zinc for fingerling Labeo rohita (6.3 ± 0.09 cm; 2.12 ± 0.08 g) by feeding casein-gelatin based seven isonitrogenous (350 g kg−1 crude protein) and isoenergetic (16.7 kJ g−1 gross energy) diets with incremental levels of zinc (9.52, 19.73, 29.84, 51.42, 71.91, 93.14 and 112.32 mg kg−1 diet). The experimental diets were hand-fed to triplicate group of fish at 08:00, 12:00 and 16:00 h to apparent satiety for 8-week. Significant improvement (P < .05) in live weight gain (LWG), specific growth rate, protein efficiency ratio, protein gain and feed conversion ratio were evident in fish fed incremental zinc levels up to 51.42 mg kg−1 (Zn4). No significant differences in the body protein and moisture contents were noted. However, body fat content decreased and ash content increased significantly with increment in zinc levels up to 51.42 mg kg−1 diet (Zn4). Zinc concentration in the whole body, liver, scales, vertebrae and serum significantly enhanced (P < .05) with increment in zinc levels up to 51.42 mg kg−1 diet and then levelled off. Fish fed basal diet (Zn1) containing 9.52 mg kg−1 dietary zinc exhibited significantly highest apparent zinc retention compared with other dietary treatment groups. The magnesium and iron contents in the whole body, liver, scales and vertebrae were significantly affected by the increasing levels of dietary zinc, but no change (P > .05) was noted in calcium and phosphorus concentrations. Haematological parameters such as haematocrit, haemoglobin, red blood cell counts, mean cell volume and mean cell haemoglobin were significantly affected (P < .05) excepting the mean cell haemoglobin concentration. Serum superoxide dismutase, glutathione peroxidase, catalase and alkaline phosphatase (ALP) activities responded positively (P < .05), while malondialdehyde concentration responded negatively up to 51.42 mg kg−1 dietary zinc level. Broken-line regression analysis of LWG, whole body, scales, vertebrae and serum zinc content, and ALP activity against dietary zinc concentrations indicated the break points at 50.90, 51.23, 49.19, 48.52, 52.93 and 47.85 mg kg−1 diet, respectively. Based on the above results of this investigation, inclusion of dietary zinc in the range of 47.85–52.93 mg kg−1 is recommended for L. rohita fingerlings for maintaining optimal growth, haematological parameters, tissue zinc concentration and antioxidant status.

Excess Dietary Zinc Intake in Neonatal Mice Causes Oxidative Stress and Alters Intestinal Host-Microbe Interactions.

Greater than 68% of young infants are exposed to dietary zinc (Zn) levels that are higher than the Tolerable Upper Intake Limit. However, the consequences of excess dietary Zn during early life on intestinal function and host-microbe interactions are unknown. Neonatal mice are gavaged with 100 Zn µgd-1 from postnatal day (PN) 2 through PN10 and indices of intestinal function and host-microbe interactions are compared to unsupplemented mice. Excess dietary Zn causes oxidative stress, increases goblet cell number and mucus production, and are associated with increased intestinal permeability and systemic inflammation. Over 900 genes are differentially expressed; 413 genes display a fold-change >1.60. The Gene Ontology Biological processes most significantly affected include biological adhesion, the immune system, metabolic processes, and response to stimulus. Key genes most highly and significantly upregulated include ALDH2, MT1, TMEM6, CDK20, and COX62b, while CALU, ST3GAL4, CRTC2, SLC28A2, and COMMA1 are downregulated. These changes are associated with a microbiome enriched in pathogenic taxa including Pseudomonadales and Campylobacter, and greater expression of bacterial stress response genes. Excess dietary Zn may have unforeseen influences on epithelial signaling pathways, barrier function, and luminal ecology in the intestine that may have long-term consequences on intestinal health.

Dietary Zinc Supplementation Prevents Autism Related Behaviors and Striatal Synaptic Dysfunction in Shank3 Exon 13-16 Mutant Mice.

The SHANK family of synaptic proteins (SHANK1–3) are master regulators of the organizational structure of excitatory synapses in the brain. Mutations in SHANK1–3 are prevalent in patients with autism spectrum disorders (ASD), and loss of one copy of SHANK3 causes Phelan-McDermid Syndrome, a syndrome in which Autism occurs in >80% of cases. The synaptic stability of SHANK3 is highly regulated by zinc, driving the formation of postsynaptic protein complexes and increases in excitatory synaptic strength. As ASD-associated SHANK3 mutations retain responsiveness to zinc, here we investigated how increasing levels of dietary zinc could alter behavioral and synaptic deficits that occur with ASD. We performed behavioral testing together with cortico-striatal slice electrophysiology on a Shank3−/− mouse model of ASD (Shank3ex13–1616−/−), which displays ASD-related behaviors and structural and functional deficits at striatal synapses. We observed that 6 weeks of dietary zinc supplementation in Shank3ex13–16−/− mice prevented ASD-related repetitive and anxiety behaviors and deficits in social novelty recognition. Dietary zinc supplementation also increased the recruitment of zinc sensitive SHANK2 to synapses, reduced synaptic transmission specifically through N-methyl-D-aspartate (NMDA)-type glutamate receptors, reversed the slowed decay tau of NMDA receptor (NMDAR)-mediated currents and occluded long term potentiation (LTP) at cortico-striatal synapses. These data suggest that alterations in NMDAR function underlie the lack of NMDAR-dependent cortico-striatal LTP and contribute to the reversal of ASD-related behaviors such as compulsive grooming. Our data reveal that dietary zinc alters neurological function from synapses to behavior, and identifies dietary zinc as a potential therapeutic agent in ASD.

Effects of Dietary Zinc on Carcass Traits, Meat Quality, Antioxidant Status, and Tissue Zinc Accumulation of Pekin Ducks.

This study investigated the effects of dietary zinc on carcass traits, meat quality, antioxidant capacity, and tissue zinc accumulation of Pekin ducks. A total of 768 1-day-old Pekin ducks were randomly allocated to six dietary treatments and penned in groups of 16 with 8 pens per treatment. Ducks were fed a basal corn-soybean meal diet supplemented with graded levels of zinc sulfate (0, 15, 30, 60, 120, 240mg zinc/kg) for 35days. The slaughter weight, carcass weight, eviscerated weight, and breast and leg muscle weight of Pekin ducks were increased with increasing dietary zinc levels (P < 0.05). Zinc supplementation increased the pH value at 24-h postmortem and the intramuscular fat (IMF) (P < 0.05), but decreased the lightness value, drip loss, and shear force in breast meat of ducks (P < 0.05). Increasing dietary zinc increased the activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), and the content of glutathione (GSH), as well as decreased the malondialdehyde (MDA) level in breast muscle (P < 0.05). RT-qPCR analysis demonstrated that supplemental zinc notably enhanced the transcription of SOD, GPX, GR, CAT, and nuclear factor erythroid 2-related factor 2 (Nrf2) (P < 0.05). Meanwhile, zinc accumulation in plasma, breast muscle, liver, and tibia were linearly increased with increasing zinc supplementation (P < 0.05). These results indicated that zinc supplementation could improve carcass traits and meat quality and increase the activities and mRNA levels of antioxidant enzymes in breast muscle of Pekin duck. Base on broken-line regression analysis that 91.32mg/kg of dietary zinc was suggested for optimal carcass traits, meat quality, antioxidant capacity, and zinc deposition of Pekin duck.

Investigations on zinc bioavailability of different sources and dietary zinc requirement in juvenile grouperEpinephelus coioides

An experiment was implemented to study the effect of dietary zinc levels from three zinc sources on growth performance, immunity, and tissue mineral elements deposition on juvenile grouper. Based on the zinc free feeds, dietary zinc levels of 0, 10, 20, 40, 80, and 160 mg/kg were added from zinc sulphate (ZnSO4), tetrabasic zinc chloride (TBZC), and 2-hydroxy-4-(methylthio) butyrate zinc (Zn-HMB). The results of the 8-week study indicated that the weight gain rate (WGR) and specific growth rate (SGR) at level 10 mg/kg were significantly higher than the control fed and the reached a plateau until level 80 mg/kg, when the sources were ZnSO4 and Zn-HMB. WGR and SGR decreased significantly at level 160 mg/kg compared to 80 mg/kg in group TBZC. Feed coefficient (FCR) of all zinc source groups showed trend of decrease before rising. The alkaline phosphatase (AKP) in serum, catalase (CAT), total superoxide dismutase (SOD), copper-zinc superoxide dismutase (Cu-Zn SOD) in liver and zinc concentrations in whole body and vertebrae increased significantly than those in control group and then kept steadily in all treatments. Regardless of the sources, the manganic content of whole body or vertebra showed a downtrend. Based on the WGR, the dietary zinc requirements in juvenile grouper were 52.94 mg/kg from ZnSO4. The average relative bioavailability (RBV) of TBZC and Zn-HMB was 169.33% and 200.33%, respectively, compared to ZnSO4.

Effects of Dietary Zinc Levels on the Growth Performance, Organ Zinc Content, and Zinc Retention in Broiler Chickens

ABSTRACT The objective of this study was to investigate the optimal zinc (Zn) requirement of broiler chickens based on Zn retention. On the day of hatch, 350 male Ross 308 broilers were randomly assigned to seven treatments with five replicates of ten birds each. Zinc was supplemented as ZnSO4·7H2O at 0, 20, 40, 60, 80, 100, or 120 mg/kg in the starter diet (fed from 1 to 21 d of age) and at 0, 16, 32, 48, 64, 80, or 96 mg/kg in the grower diet (fed from 22 to 42 d of age). The analyzed Zn levels were 34.98 and 27.57 mg/kg in the basal starter and grower diets, respectively. Supplemental Zn levels did not influence body weight gain, feed intake, feed conversion ratio, or liver Zn content of broilers at 21 and 42 d of age (p>0.05). Tibia ash Zn content of 21-d-old broilers increased when Zn supplementation level increased from 0 to 40 mg/kg Zn in (p<0.05). The highest breast muscle Zn content in 42-d-old broilers was observed when 100 and 80 mg Zn/kg was supplemented in the starter and grower diets, respectively. Fecal Zn content, Zn intake, Zn excretion, and Zn retention of 31- to 33-d-old broilers linearly increased with supplemental Zn levels (p<0.05). Zinc retention values, calculated as the difference between Zn intake and Zn excretion, were negative, about zero, and positive when starter/grower diets were supplemented with 0/0 and 20/16, 40/32, and 60/48 and 120/96 mg/kg, respectively. These results indicate that supplementing 40 and 32 mg Zn/kg in starter and grower diets, respectively, promote the growth performance of broiler chickens, while reduce Zn excretion in the environment.

Effects of dietary zinc level on performance, zinc status, tissue composition and enzyme activities of juvenile Siberian sturgeon, Acipenser baerii (Brandt 1869)

Effects of dietary zinc level on performance, zinc status, tissue composition and enzyme activities of juvenile Siberian sturgeon, <i>Acipenser baerii</i> (Brandt 1869)

Identification of possible nutritional and stress risk factors in the development of marmoset wasting syndrome.

Marmoset wasting syndrome (MWS) describes a series of symptoms in callitrichids that lead to general weakness and a failure to thrive in captive conditions such as zoological institutions. Though the cause of MWS has not been identified, the majority of hypotheses are linked to deficiencies of specific nutrients and increased stress levels. Questionnaires were sent to zoos requesting information on diets and housing of currently living and dead callitrichids before their deaths, as well as their postmortem reports. Risk factors for development and occurrence of MWS include close proximity of predator enclosures and high levels of dietary magnesium and zinc. Variables with effects which may protect against the development of MWS included provision of a nest box, natural trees within enclosure, reduced visibility to visitors, as well as dietary factors such as higher concentrations of potassium and fiber fractions. The protective effects of limited concentrate feeds and increased total dietary fiber may help reduce the risks of developing MWS. The minerals may not have biological implications in MWS per se, however, they may be reflective of diets too high in concentrates and too low in plant matter. Habitat designs that are less naturalistic and those which provide insufficient privacy or hide areas may increase chronic stress for callitrichid species, possibly because of visitor-related stress. Other causes of chronic stress in captive zoo populations should be the topic of further research to reduce occurrence of MWS.

Increasing zinc levels in phytase-supplemented diets improves the performance and nutrient utilization of broiler chickens

Three hundred and thirty-six day-old Ross-308 male broiler chicks were used in a 35-day trial to investigate the effect of different concentrations of dietary Zn and phytase on broiler performance and energy utilization. Twelve day-old birds were used for the initial slaughter group to provide baseline body compositional data, while the remaining 324 birds were randomly distributed to six experimental diets. The treatments consisted of a 3 x 2 factorial arrangement with three levels of Zn (low, mid, and high; 30, 40, and 50 mg/kg, respectively) and two levels (0, 500 FTU/kg) of microbial phytase. Each dietary treatment was fed to 6 cages (9 birds/cage). Low Zn diet significantly decreased feed intake and body weight gain at days 1-24. Phytase supplementation improved body weight gain at d 24, irrespective of Zn level. The digestibility of P was improved in birds fed high-Zn diet with phytase supplementation, and the reverse was the case for Fe and Zn digestibility. High dietary Zn increased the Zn and Fe deposition in liver. The activity of AP, Ca-ATPase and Mg-ATPase in the jejunum was high in the phytase supplemented mid-level Zn diet. Phytase supplemented to the mid and high level Zn diets significantly improved most energy utilization parameters. This result indicate that the Zn concentrations used in this study were not inhibitory to phytase activity and broiler performance. Therefore, it can be concluded that dietary zinc level in phytase-supplemented diets could be increased up to 50 mg/kg without any negative effect on phytase-mediated broiler response.Keywords: Bone quality, net energy, nutrient utilization

Effect of Zinc Supplementation on Growth Performance, Intestinal Development, and Intestinal Barrier-Related Gene Expression in Pekin Ducks.

The current study was conducted to investigate the effect of zinc supplementation on the growth performance, intestinal morphology, and the transcription of the barrier function related genes in Pekin ducks. Seven-hundred and sixty-eight 1-day-old Pekin ducks were randomly assigned into six dietary treatments. Each treatment had eight replicates with 16 ducks per replicates. The ducks were fed either a corn-soybean meal basal diet or basal diets supplemented with 15, 30, 60, 120, and 240mg zinc/kg from zinc sulfate. This experiment lasted for 5weeks, and the jejunum sample were harvested at 14 and 35days of age. Results have shown that diets supplemented with zinc significantly increased the duck body weight, average daily gain, and average daily feed intake in different period of experiment (P<0.05); feed to gain ratio was decreased as the zinc level increased (P<0.05). Zinc supplementation increased the villus height and decreased the crypt depth in jejunum of ducks (P<0.05) at 14 and 35days of age. The transcription of tight junction protein CLDN1, OCND, ZO-1, and ZO-3 in jejunum were increased (P<0.05), and the messenger RNA (mRNA) levels of leak protein CLDN2 were decreased as the dietary zinc level increased (P<0.05) at 14 and 35days of age. The mRNA levels of chemical barrier-related genes MUC2 and TFF-2 in jejunum at 14 and 35days of age were increased (P<0.05) by zinc supplementation, and so did the transcription of immunological barrier-related genes lgA, pIgR, LYZ, and AvBD2 (P<0.05). In conclusion, dietary zinc supplementation exhibited growth-promoting effect on Pekin duck, improved intestinal morphology, and enhanced the intestinal barrier integrity.

Effect of Sources and Levels of Dietary Zinc on the Performance, Carcass Traits and Blood Parameters of Broilers

ABSTRACT A total of 400 one-day-old, straight-run, commercial (Ross 308) broiler chicks were used to evaluate the effects of two dietary levels of zinc (Zn) sources on broiler chick performance, carcass traits and blood parameters. Corn-soybean diets were formulated for three rearing phases (starter, grower and finisher). The two dietary treatments applied consisted of the addition per kg of diet of 80mg of inorganic Zn (ZnO) (T1), or 80mg of ZnO plus 42mg of an organic Zn-amino acid complex (Availa-Zn120; Zinpro Corporation, Eden Prairie, MN, USA), totaling 122mg of the combined organic and inorganic Zn sources (T2). Birds were distributed according to a completely randomized design in the two treatments with eight replicates (pens) of 25 birds each. Feed and water were provided ad libitum. On day 42, blood samples were taken from four birds closest to the group average weight per replicate (32 per treatment) and then slaughtered for carcass evaluation. The results of this study did not find any significant effect of either of the evaluated Zn sources on broiler growth performance. Mortality rate was significantly lower (p<0.05) by the higher Zn concentration and the Zn sources group (T2). Carcass yields were not significantly influenced by the treatments. Breast quality showed significant improvement (p<0.05) in shear force (T2), indicating juicier meat. Higher concentrations (p<0.05) of Zn, Phosphorus (P), and total protein in blood were noted in (T2). Birds fed a mixture of organic and inorganic Zn source (T2) presented overall better results.

A role for the Drosophila zinc transporter Zip88E in protecting against dietary zinc toxicity.

Zinc absorption in animals is thought to be regulated in a local, cell autonomous manner with intestinal cells responding to dietary zinc content. The Drosophila zinc transporter Zip88E shows strong sequence similarity to Zips 42C.1, 42C.2 and 89B as well as mammalian Zips 1, 2 and 3, suggesting that it may act in concert with the apically-localised Drosophila zinc uptake transporters to facilitate dietary zinc absorption by importing ions into the midgut enterocytes. However, the functional characterisation of Zip88E presented here indicates that Zip88E may instead play a role in detecting and responding to zinc toxicity. Larvae homozygous for a null Zip88E allele are viable yet display heightened sensitivity to elevated levels of dietary zinc. This decreased zinc tolerance is accompanied by an overall decrease in Metallothionein B transcription throughout the larval midgut. A Zip88E reporter gene is expressed only in the salivary glands, a handful of enteroendocrine cells at the boundary between the anterior and middle midgut regions, and in two parallel strips of sensory cell projections connecting to the larval ventral ganglion. Zip88E expression solely in this restricted subset of cells is sufficient to rescue the Zip88E mutant phenotype. Together, our data suggest that Zip88E may be functioning in a small subset of cells to detect excessive zinc levels and induce a systemic response to reduce dietary zinc absorption and hence protect against toxicity.

Dietary Levels of Zinc and Manganese on the Performance of Broilers Between 1 to 42 Days of Age

The objective of this study was to determine the optimal dietary concentration of zinc and manganese on the performance characteristic and the requirement of these trace minerals derived from organic sources for broilers from 1 to 42 days of age. In experiment 1, zinc was evaluated, whereas manganese was evaluated in experiment 2. In each experiment, 320 males chicks were distributed in iron mesh metabolic cages (0.9m x 0.7m x 0.5m), according to a completely randomized experimental design in eight treatments with five replicates of eight birds each. In experiment 1, zinc sulfate was included at 0,60 and 100mg/kg and zinc methionine at 20, 40, 60, 80 and 100mg/kg. In experiment 2, manganese sulfate was added at 0, 65 and 105mg/kg and manganese methionine at 25, 45, 65, 85 and 105 mg/kg. Trace mineral requirements were determined comparing only organic trace mineral levels. The evaluated trace minerals (zinc and manganese) did not influence broiler performance, independently of source or level. It was concluded that the requirements of broilers from 1 to 42 days of age were supplied with no addition of zinc or manganese, under the conditions of the present experiments. However, under commercial rearing conditions, which are more challenging, the use of levels higher than 33.00 mg/kg and37.80 mg/kg of zinc and manganese, respectively, may be justified.

Effects of dietary organic zinc and α-tocopheryl acetate supplements on growth performance, meat quality, tissues minerals, and α-tocopherol deposition in broiler chickens

The aim of this study was to evaluate the effects of different dietary levels of zinc (Zn) and α-tocopheryl acetate (α-TOA) on broilers performance, meat quality, Zn, selenium (Se), and α-tocopherol (α-TO) tissue depositions. A total of 1,080 one-day-old Ross 308 broiler chickens (mixed-sex) were allocated to nine dietary treatments. Three levels of supplemental Zn (0, 60, and 120 mg/kg of diet) and three levels of α-TOA (0, 150, and 300 mg/kg of diet) were combined as a completely randomized design with 3 × 3 factorial arrangement. Chicks were penned in groups of 20 with six pens per treatment. The ADFI, ADG, feed conversion ratio (FCR), mortality rate, and European production efficiency factor (EPEF) were not affected by dietary treatments. In addition, supplementation of Zn and α-TOA and their interaction did not affect carcass parts yield. Drip loss of the breast and thigh muscles were significantly reduced 1.27 and 1.47% by α-tocopheryl acetate (α-TOA) supplementation, respectively (P < 0.01). Deposition of Zn in liver, breast, and thigh muscles were linearly increased by dietary Zn supplementation. Furthermore, supplementation of Zn increased Se content in the breast and thigh muscles and liver. Supplementation of either α-TOA or Zn increased deposition of α-TO in liver and the muscles. The Thiobarbituric acid reactive substances (TBARS) values in the breast and thigh muscles and the liver were diminished by supplementation of α-TOA (P = 0.0001) and there was positive interaction between Zn and α-TOA (P < 0.01), in which within each increase in Zn supplementation level, α-TOA supplementation resulted in a reduction of TBARS values. In conclusion, 300 mg/kg dietary supplementation of α-TOA could improve drip loss, nutritional content, and oxidation stability of muscle without any adverse effect on growth performance of chickens. In addition, 120 mg/kg dietary supplementation of Zn could fortify α-TOA effect to improve oxidation stability of the breast and thigh muscles as well as it resulted to higher muscles Zn enrichment.

Metallothionein‐2A mRNA in Peripheral Blood Mononuclear Cells Reflects Dietary Zinc Intake in Healthy Adults

Zinc is an essential nutrient for humans;however, a sensitive biomarker to assess zinc status has not been identified. Metallothionein(MT)‐1 and –2 are ubiquitously expressed proteins that bind cellular zinc with high affinity. MT expression is induced through binding of zinc to metal‐regulatory transcription factor 1, which then binds to metal‐responsive elements in the promoter of the metallothionein gene. The objective of this study was to determine whether expression of MT1 and/or MT2 in peripheral blood mononuclear cells (PBMCs) is associated with dietary zinc intake in healthy human adults. Forty‐three male and female volunteers (33.6 ± 14.3 y, BMI 25.6 ±2.86 kg/m2) completed a Block Food Frequency Questionnaire (v. 2014)to assess habitual dietary zinc intake. Blood was collected and plasma and PBMCs were isolated. RNA was isolated from PBMCs and expression of MT1A and MT2A mRNA was determined by RT‐qPCR. Plasma MT2A protein was determined by ELISA and plasma zinc concentration was determined by atomic absorption spectroscopy. Average daily zinc intake was 15.5 ± 7.44 mg/d (range: 4.89‐31.7mg/d). Plasma zinc concentration (10.8 ± 1.01 μmol/L) did not reflect dietaryzinc intake (r=0.0890; P=0.586). PBMC MT2Aexpression was 9‐fold greater than MT1A (11.5E‐3± 0.0127, 1.30E‐3 ± 0.00527; P&lt;0.05). MT1Aexpression in PBMCs was not correlated with dietary zinc intake (r=0.137; P=0.383). MT2A expression in PBMCs was positively correlated with dietary zinc intake (r= 0.302; P&lt;0.05) and increased with increasing levels of dietary zinc (&lt;11 mg zinc/d, 7.29E–3 ± 0.00881; 11–20mg zinc/d, 9.93E–3 ± 0.0141; &gt;20 mg zinc/d, 15.4E–3 ± 0.0114; P&lt;0.05). Plasma MT2A protein was not correlated with dietary zinc intake (r=−0.0840;P=0.605). Findings suggest that MT2A mRNA in PBMCs reflects dietary zinc intake in healthy adults and may be a component in determining zinc status.Support or Funding InformationThe views expressed in this abstract are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government. Support provided by USAMRMC.

Effect of Dietary Replacement of Inorganic Zinc by Organic or Nanoparticles Sources on Growth Performance, Immune Response and Intestinal Histopathology of Broiler Chicken

Two hundred and twenty-five one day-old avian chicks were used to investigate the effect of different dietary supplemental zinc sources and levels on growth performance, blood picture and biochemical parameters, immune response, carcass characteristics and intestinal morphology of broiler chickens. Birds were randomly allocated into 9 groups which fed on the experimental basal diet supplemented with different zinc sources and levels; group 1 was fed basal diet supplemented with (60 ppm) inorganic zinc oxide, while groups 2, 3, 4 and 5 were supplemented with (60, 45, 30 or 15 ppm) organic zinc (polysaccharide-zinc complex) respectively and groups 6, 7, 8 and 9 were supplemented with (60, 45, 30 or 15ppm) zinc oxide nanoparticles respectively. Broiler chickens fed 60 or 45 ppm organic zinc improved growth performance while, lower supplementation levels (30 or 15ppm) had no significant effect. Moreover, zinc nanoparticles supplementation at 60, 45 or 30 ppm improved growth performance while lower level (15ppm) significantly reduced broiler performance and feed efficiency parameters. Using organic or nano zinc reduced total feed intake of broiler chicken. Organic or nano zinc supplementation non-significantly reduced blood serum lipids and increased GOT or GPT concentrations compared with those fed on diet supplemented with inorganic zinc. Moreover, organic or nano zinc had no significant effect on antioxidant enzyme activity while reduced abdominal fat weight. Organic zinc or nano zinc supplementation improved phagocytic activity, antibody production against Newcastle Disease vaccine, lymphoid organs weight and improve intestinal villi length, width and crypt depth of broiler chicken.

An Optimal Dietary Zinc Level of Brown-Egg Laying Hens Fed a Corn-Soybean Meal Diet.

An experiment was conducted to estimate the optimal dietary zinc (Zn) level of brown-egg laying hens fed a corn-soybean meal diet from 20 to 40weeks of age. A total of 120 20-week-old Beijing Red commercial laying hens were randomly allotted by bodyweight to one of five treatments with six replicates of four birds each in a completely randomized design, and fed a Zn-unsupplemented corn-soybean meal basal diet containing 27.95mg Zn/kg by analysis and the basal diets supplemented with 30, 60, 90, or 120mg Zn/kg as Zn sulfate (reagent grade ZnSO4·7H2O) for a duration of 20weeks. Laying performance, egg quality, tissue Zn concentrations, and activities of serum alkaline phosphatase (AKP), and liver copper-Zn superoxide dismutase (CuZnSOD) were measured. Regression analyses were performed to estimate an optimal dietary Zn level whenever a significant quadratic response (P<0.05) was observed. Tibia Zn concentration (P=0.002) and serum AKP activity (P=0.010) showed significant quadratic responses to dietary supplemental Zn levels. The estimates of dietary Zn requirements for brown-egg laying hens from 20 to 40weeks of age were 71.95 and 64.63mg/kg for tibia Zn concentration and serum AKP activity, respectively. The results from this study indicate that the tibia Zn might be a more suitable and reliable parameter for Zn requirement estimation, and the optimal dietary Zn level would be about 72mg/kg for brown-egg laying hens fed a corn-soybean meal diet from 20 to 40weeks of age.