Trace elements, innate immune response and parasites

Nutrient Deficiencies and Potential Alteration in Plasma Levels of Naturally Acquired Malaria-Specific Antibody Responses in Tanzanian Children

Immunoglobulin G (IgG) subclasses have been suggested to confer naturally acquired immunity to Plasmodium falciparum malaria. Cytophilic IgG1 and IgG3 with their potential for opsonization, phagocytosis, and antibody-dependent cellular inhibition in association with monocytes have been suggested to have a critical role in malaria. The potential for production of antibodies is influenced by micronutrient status. This study aimed at exploring the effect of micronutrients, particularly zinc status, on the profiles of IgG subclasses in 304 Tanzanian children aged ≤ 5 years. An enzyme-linked immunosorbent assay was performed using whole asexual blood stage malaria antigens to determine plasma malaria-specific antibody titers. This baseline cross-sectional study was done from 2005 – 2010 prior to the larger randomized control trial of the Micronutrient and Child Health (MACH) Study. Plasma concentrations of zinc and magnesium were measured by inductively coupled plasma atomic emission spectrometry and results correlated with plasma IgG subclass levels. The findings reveal zinc deficiency to possibly influence the production of IgM, total IgG, and several IgG subclasses in a malaria status-dependent manner. Among IgG subclasses, IgG3 and partly IgG2 displayed a remarkable association with zinc deficiency, particularly IgG3 which was predominant in children with malaria. Nevertheless, zinc, magnesium, and malaria status did not influence the association between IgG3 and IgG4. The study leads to the conclusion that, under conditions of micronutrient deficiency and malaria status, an imbalance in IgG subclass production may occur leading to predominantly higher levels of IgG3 and IgG2 that may not confer sufficient protection from infection. The profile of both cytophilic and non-cytophilic IgG subclasses has been shown to be variably influenced by zinc status; the effects vary with age at least in under-fives. These results provide insight for inclusion of micronutrients, particularly precise amounts of zinc, in future malaria interventional programs in endemic areas.

Selenium, TGF-Beta and Infectious Endemic Cardiopathy: Lessons from Benchwork to Clinical Application in Chagas Disease

For over 60 years, selenium (Se) has been known as an essential microelement to many biological functions, including cardiovascular homeostasis. This review presents a compilation of studies conducted in the past 20 years related to chronic Chagas disease cardiomyopathy (CCC), caused by Trypanosoma cruzi infection, a neglected disease that represents a global burden, especially in Latin America. Experimental and clinical data indicate that Se may be used as a complementary therapy to prevent heart failure and improve heart function. Starting from the main questions “Is Se deficiency related to heart inflammation and arrhythmogenesis in CCC?” and “Could Se be recommended as a therapeutic strategy for CCC?”, we show evidence implicating the complex and multidetermined CCC physiopathology, discussing its possible interplays with the multifunctional cytokine TGF-β as regulators of immune response and fibrosis. We present two new proposals to face this global public health challenge in vulnerable populations affected by this parasitic disease: fibrosis modulation mediated by TGF-β pathways and the possible use of selenoproteins as antioxidants regulating the increased reactive oxygen stress present in CCC inflammatory environments. We assess the opportunity to consider the beneficial effects of Se in preventing heart failure as a concept to be applied for CCC patients.

Selenium as an interesting option for the treatment of Chagas disease: A review

Chagas disease is one of the most prevalent tropical neglected diseases and causes high mortality and morbidity in endemic countries. Current treatments for this disease, nifurtimox and benznidazole, are ineffective in the chronic phase of the disease and produce severe adverse effects. Therefore, novel therapies are urgently required. The trace element selenium has an important role in human health, due to its antioxidant, antiinflammatory and pro-immune properties. Actually, its deficiency has been related to several diseases and supplementation with this element has been proven to be beneficial for multiple pathologies. Furthermore, the usefulness of organic-selenium compounds has been studied in many disorders, showing promising results. The aim of this review is to analyse the available literature regarding the role of selenium in Chagas disease in order to determine whether its use could be beneficial for the management of this pathology.

Pesticide Exposure and Stunting among Children in Agricultural Areas

BACKGROUND

The prevalence of growth disorders among school-aged children in Indonesia is high (30.7%). Pesticides have been massively used in Indonesian agricultural areas.

OBJECTIVE

To determine if exposure to pesticides is associated with stunting among children in agricultural areas.

METHODS

This case-control study included 160 children (48 cases and 112 controls) aged 8-12 years. Exposure to pesticides was measured based on the history of the exposure since perinatal period, infancy, and childhood of the participants. Stunting was determined as a height for age z-score (HAZ) < ‑2 SD. Other variables measured were levels of thyroid stimulating hormone (TSH), insulin-like growth factor-1 (IGF-1), hemoglobin, zinc, albumin, nutrient adequacy level (energy and protein), and history of infection, low-birth weight (LBW), and mother's height.

RESULTS

There were no significant difference between the cases and controls in terms of in the baseline characteristics, except for the median IGF-1 level; it was significantly (p<0.001) lower in the cases (66.73 ng/mL) than the controls (112.57 ng/mL). High level of pesticide exposure (p=0.029) and low IGF-1 levels (p<0.001) were significantly associated with stunting. After adjusting for confounding variables, these variables were found to be independent risk factors for stunting in children (aOR 3.90, 95% CI 1.15 to 13.26; and aOR 8.35, 95% CI 3.65 to 19.14, respectively).

CONCLUSION

Pesticide exposure could be a risk factor for the occurrence of growth disorders in children living in agricultural areas. Necessary actions should be taken to protect children living in agricultural areas from exposure to pesticides.

Quadruple burden of HIV/AIDS, tuberculosis, chronic intestinal parasitoses, and multiple micronutrient deficiency in ethiopia: a summary of available findings

Human immunodeficiency virus (HIV), tuberculosis (TB), and helminthic infections are among the commonest public health problems in the sub-Saharan African countries like Ethiopia. Multiple micronutrient deficiencies also known as the “hidden hunger” are common in people living in these countries either playing a role in their pathogenesis or as consequences. This results in a vicious cycle of multiple micronutrient deficiencies and infection/disease progression. As infection is profoundly associated with nutritional status resulting from decreased nutrient intake, decreased nutrient absorption, and nutrient losses, micronutrient deficiencies affect immune system and impact infection and diseases progression. As a result, micronutrients, immunity, and infection are interrelated. The goal of this review is therefore to provide a summary of available findings regarding the “quadruple burden trouble” of HIV, TB, intestinal parasitic infections, and multiple micronutrient deficiencies to describe immune-modulating effects related to disorders.

Dietary plant phenolic improves survival of bacterial infection in Manduca sexta caterpillars

Plant phenolics are generally thought to play significant roles in plant defense against herbivores and pathogens. Many plant taxa, including Solanaceae, are rich in phenolic compounds and some insect herbivores have been shown to acquire phenolics from their hosts to use them as protection against their natural enemies. Here we demonstrate that larvae of an insect specialist on Solanaceae, the tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae), acquire the plant phenolic chlorogenic acid (CA), and other caffeic acid derivatives as they feed on one of their hosts, Nicotiana attenuata L. (Solanaceae), and on artificial diet supplemented with CA. We test the hypothesis that larvae fed on CA-supplemented diet would have better resistance against bacterial infection than larvae fed on a standard CA-free diet by injecting bacteria into the hemocoel of fourth instars. Larvae fed CA-supplemented diet show significantly higher survival of infection with Enterococcus faecalis (Andrewes & Horder) Schleifer & Kilpper-Bälz, but not of infection with the more virulent Pseudomonas aeruginosa (Schroeter) Migula. Larvae fed on CA-supplemented diet possess a constitutively higher number of circulating hemocytes than larvae fed on the standard diet, but we found no other evidence of increased immune system activity, nor were larvae fed on CA-supplemented diet better able to suppress bacterial proliferation early in the infection. Thus, our data suggest an additional defensive function of CA to the direct toxic inhibition of pathogen proliferation in the gut.

Effect of vitamin A deficiency on the immune response in obesity

Obesity has been associated with low-grade systemic inflammation and with micronutrient deficiencies. Obese individuals have been found to have lower vitamin A levels and lower vitamin A intake compared with normal-weight individuals. Vitamin A plays a major role in the immune function, including innate immunity, cell-mediated immunity and humoral antibody immunity. It has also been recognised recently that vitamin A has important regulatory functions. Vitamin A status has an important effect on the chronic inflammatory response. Vitamin A deficiency increases a T-helper type 1 (Th1) response, elevates levels of pro-inflammatory cytokines, increases the expression of leptin, resistin and uncoupling proteins (UCP) and promotes adipogenesis. The effect of vitamin A deficiency on obesity might be increasing the risk of fat deposition and also the risk of chronic inflammation associated with obesity. Supplementation with vitamin A in vitro and in animal models has been found to reduce concentrations of adipocytokines, such as leptin and resistin. In conclusion, vitamin A deficiency increases a Th1 response in the presence of obesity and thus, increases the inflammatory process involved in chronic inflammation and fat deposition. The metabolism of leptin and other adipocytokines may play a critical role in the effect of vitamin A deficiency in the inflammatory response observed in obesity.

Influence of organic zinc supplementation on the antioxidant status and immune responses of broilers challenged with Eimeria tenella

An experiment was conducted to investigate the influence of Zn supplementation on the performance, antioxidant status, and immune responses of broilers challenged with Eimeria tenella. A total of 384 male broilers (1 d old) were assigned to 8 treatments consisting of 8 replicates of 6 chicks each. A basal corn-soybean meal diet (29.6 mg of Zn/kg) was supplemented with methionine hydroxyl analog-Zn chelate at 0, 20, 40, and 60 mg/kg of diet. At 21 d of age, birds were orally gavaged with 1.5 × 10(4) sporulated E. tenella oocysts. Dietary Zn supplementation had no effect on growth performance of either the challenged or nonchallenged birds. Activities of Cu-Zn superoxide dismutase and glutathione peroxidase were increased (P < 0.001) with increasing Zn levels in both the challenged and nonchallenged groups. Lipid peroxidation tended to be reduced (P = 0.08) at Zn inclusion of 20 and 40 mg/kg. In vitro lymphocyte proliferation responses to mitogen concanavalin A and LPS were not influenced by dietary Zn or challenge. The main effects of Zn level and challenge were significant for secretory IgA on d 28 (P < 0.01) and 35 (P < 0.001). During both periods, secretory IgA of birds receiving dietary Zn supplementation was higher (P < 0.05) than that of those receiving no Zn supplementation. Birds fed Zn supplementation excreted fewer oocysts in the excreta than those receiving no Zn supplement (P < 0.001). Results indicated that organic Zn supplementation reduced oxidative stress and improved some immune responses irrespective of whether birds were healthy or challenged with E. tenella.

Regulatory T cells phenotype in different clinical forms of Chagas' disease

CD25(High) CD4+ regulatory T cells (Treg cells) have been described as key players in immune regulation, preventing infection-induced immune pathology and limiting collateral tissue damage caused by vigorous anti-parasite immune response. In this review, we summarize data obtained by the investigation of Treg cells in different clinical forms of Chagas' disease. Ex vivo immunophenotyping of whole blood, as well as after stimulation with Trypanosoma cruzi antigens, demonstrated that individuals in the indeterminate (IND) clinical form of the disease have a higher frequency of Treg cells, suggesting that an expansion of those cells could be beneficial, possibly by limiting strong cytotoxic activity and tissue damage. Additional analysis demonstrated an activated status of Treg cells based on low expression of CD62L and high expression of CD40L, CD69, and CD54 by cells from all chagasic patients after T. cruzi antigenic stimulation. Moreover, there was an increase in the frequency of the population of Foxp3+ CD25(High)CD4+ cells that was also IL-10+ in the IND group, whereas in the cardiac (CARD) group, there was an increase in the percentage of Foxp3+ CD25(High) CD4+ cells that expressed CTLA-4. These data suggest that IL-10 produced by Treg cells is effective in controlling disease development in IND patients. However, in CARD patients, the same regulatory mechanism, mediated by IL-10 and CTLA-4 expression is unlikely to be sufficient to control the progression of the disease. These data suggest that Treg cells may play an important role in controlling the immune response in Chagas' disease and the balance between regulatory and effector T cells may be important for the progression and development of the disease. Additional detailed analysis of the mechanisms on how these cells are activated and exert their function will certainly give insights for the rational design of procedure to achieve the appropriate balance between protection and pathology during parasite infections.

Echinacea purpurea along with zinc, selenium and vitamin C to alleviate exacerbations of chronic obstructive pulmonary disease: results from a randomized controlled trial

WHAT IS KNOWN AND OBJECTIVE

Upper respiratory tract infections (URTI) frequently cause exacerbations of chronic-obstructive pulmonary disease (COPD). Stimulation of the innate immune system may provide an early defence against such infections. The objective of this study was to determine whether Echinacea purpurea (EP) along with micronutrients may alleviate COPD exacerbations caused by acute URTI.

METHODS

This was a double-blind, randomized, placebo-controlled trial in COPD patients with acute URTI. Patients were given ciprofloxacin for 7 days and additionally one tablet per day of EP, of EP along with zinc, selenium and ascorbic acid (EP+), or of placebo until day 14. Serum levels of TNF α and interleukins 1β, 6 and 10 were measured before and after treatment. Until week 4 post-end of treatment, all patients had to daily report on COPD symptoms in diaries.

RESULTS AND DISCUSSION

In total, 108 mostly male patients with a mean age of 65·8 years (40-81 years) were enrolled. Patients of the three treatment arms did not vary significantly in baseline characteristics. EP+, but not EP resulted in significantly less severe and shorter exacerbation episodes following URTI as compared with placebo suggesting a synergistic effect of Echinacea and micronutrients. Large variations in biomarkers in-between and within groups were unrelated to treatment. Study medication was safe and well tolerated with overall 15 adverse events one of which was serious. Among those, sleeping disorders were most frequent and likely related to the underlying disease.

WHAT IS NEW AND CONCLUSION

The combination of EP, zinc, selenium and vitamin C may alleviate exacerbation symptoms caused by URTI in COPD. Further studies are warranted to investigate the interactions among Echinacea, zinc, selenium and vitamin C.

Alterations in early cytokine-mediated immune responses to Plasmodium falciparum infection in Tanzanian children with mineral element deficiencies: a cross-sectional survey

Background

Deficiencies in vitamins and mineral elements are important causes of morbidity in developing countries, possibly because they lead to defective immune responses to infection. The aim of the study was to assess the effects of mineral element deficiencies on early innate cytokine responses to Plasmodium falciparum malaria.

Methods

Peripheral blood mononuclear cells from 304 Tanzanian children aged 6-72 months were stimulated with P. falciparum-parasitized erythrocytes obtained from in vitro cultures.

Results

The results showed a significant increase by 74% in geometric mean of TNF production in malaria-infected individuals with zinc deficiency (11% to 240%; 95% CI). Iron deficiency anaemia was associated with increased TNF production in infected individuals and overall with increased IL-10 production, while magnesium deficiency induced increased production of IL-10 by 46% (13% to 144%) in uninfected donors. All donors showed a response towards IL-1β production, drawing special attention for its possible protective role in early innate immune responses to malaria.

Conclusions

In view of these results, the findings show plasticity in cytokine profiles of mononuclear cells reacting to malaria infection under conditions of different micronutrient deficiencies. These findings lay the foundations for future inclusion of a combination of precisely selected set of micronutrients rather than single nutrients as part of malaria vaccine intervention programmes in endemic countries.

Effect of zinc on lysozyme-like activity of the seastar Marthasterias glacialis (Echinodermata, Asteroidea) mucus

Lysozyme represents the best characterized enzyme involved in the self-defense from bacteria. In this study we analysed the effects of zinc on the lysozyme-like activity of the seastar Marthasterias glacialis mucus. This activity, detected by measuring the cleared lysis area of dried Micrococcus lysodeikticus cell walls on Petri dishes, was significantly reduced in presence of zinc. The results are discussed in the light of elucidating the possible relationship between environmental contaminants and increased disease susceptibility in seastars due to the decrease of antibacterial protection. The benefits of using the test of lysozyme activity to monitoring environmental pollution are highlighted.

Calorie restriction and susceptibility to intact pathogens

Long-term calorie restriction (CR) causes numerous physiological changes that ultimately increase mean and maximum lifespan of most species examined to date. One physiological change that occurs with CR is enhanced immune function, as tested using antigens and mitogens to stimulate an immune response. Fewer studies have used intact pathogen exposure to test whether the enhanced capacity of the immune response during CR actually decreases susceptibility of hosts to their pathogens. So far, studies using intact bacteria, virus, and helminth worm exposure indicate that, despite similar or enhanced immune system function, CR hosts are more susceptible to infection by intact pathogens than their fully fed counterparts. Long-term CR studies that examine susceptibility to a variety of parasite taxa will help determine if direct CR or CR mimetics will be beneficial to people living in pathogen-rich environments.

Effect of selenium and Ascaridia galli infection on antioxidant biomarkers in broiler chickens: a mathematical model for parasite reduction and host growth

The activity of selenium-dependent glutathione peroxidase (GPX), liver concentration of vitamin E, and plasma and liver selenium levels were used for estimation of the antioxidant status of broiler chickens infected with Ascaridia galli. These biomarkers were recorded in an experiment covering 70 days p.i. At the same time the establishment rate of A. galli in chicken intestines, gain in the host body weight and chicken survival were studied. Broiler chickens (Cobb hybrids) were infected with 1450 embryonated A. galli eggs and treated with Sel-plex. A mathematical model was applied to determine the rate of nematode reduction and the relative rate of gain of host body weight, which are essential kinetic parameters of parasite-host interaction. The activity of GPX increased with both elevated selenium and reduced infection levels. The concentrations of selenium and vitamin E, and the GPX activity in the infected chickens demonstrated a similar pattern of change with time after day 30 p.i. The supplementation of the broilers with dietary selenium in the form of Sel-plex improved their antioxidant status. Increases by 29% in vitamin E concentration, 15% in GPX activity, and 22% in liver selenium concentration, respectively, were recorded in the infected and treated, compared to infected and untreated broilers.

Amelioratory effects of zinc supplementation on Salmonella-induced hepatic damage in the murine model

Zinc (Zn) has been reported to influence the susceptibility of the host to a diverse range of infectious pathogens, including viruses, bacteria, fungi and protozoa. We report here an evaluation of the effects of Zn supplementation on Salmonella enterica serovar Typhimurium (S. typhimurium)-induced hepatic injury in the murine model. Zinc levels in the plasma and liver tissues were measured by atomic absorption spectroscopy. The effect of Zn supplementation was evaluated by assessing the bacterial load and levels of lipid peroxidation (LPO), antioxidants and monokines present in the hepatic tissue as well as by histopathological studies. Zinc supplementation reduced the bacterial load in the liver and reversed hepatic microscopic abnormalities. It also decreased the levels of LPO but increased the levels of reduced glutathione (GSH) as well as the activities of superoxide-dismutase (SOD) and catalase in the livers of infected mice supplemented with Zn compared to the livers of infected mice not supplemented with Zn. Zinc supplementation was also able to modulate the levels of monokines such as tumour necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6). Our results indicate a role for Zn in downregulating oxidative stress and upregulating antioxidant defense enzymes through the action of monokines, suggesting that supplementation with Zn has a protective function in Salmonella-induced liver injury.

Interactions among infections, nutrients and xenobiotics

During recent years there have been several incidents in which symptoms of disease have been linked to consumption of food contaminated by chemical substances (e.g., 2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD). Furthermore, outbreaks of infections in food-producing animals have attracted major attention regarding the safety of consumers, e.g., Bovine Spongiform Encephalitis (BSE) and influenza in chicken. As shown for several xenobiotics in an increasing number of experimental studies, even low-dose xenobiotic exposure may impair immune function over time, as well as microorganism virulence, resulting in more severe infectious diseases and associated complications. Moreover, during ongoing infection, xenobiotic uptake and distribution are often changed resulting in increased toxic insult to the host. The interactions among infectious agents, nutrients, and xenobiotics have thus become a developing concern and new avenue of research in food toxicology as well as in food-borne diseases. From a health perspective, in the risk assessment of xenobiotics in our food and environment, synergistic effects among microorganisms, nutrients, and xenobiotics will have to be considered. Otherwise, such effects may gradually change the disease panorama in society.

Body weight, early growth and antler size influence antler bone mineral composition of Iberian red deer (Cervus elaphus hispanicus)

Researchers have devoted little attention to the possibility that the chemical composition of bone might be variable under normal nutrition conditions. This study assessed antler bone composition of 25 one-year old deer (spikes). Antler content of ash, Ca, P, K, Na, Mg, Fe and Zn was assessed in base and tine, and the mean composition or the difference in composition between tine and base was used to explain variability in antler length, weight and perimeter. In turn, mean composition and difference in concentration of each mineral were related to body measures at 1 year of age, weight at birth, weight at 1 year of age and weight gains during lactation, or between weaning and year of age. Chemical composition differed between base and tine in ash, Ca, P, K, Zn and Fe, but not in Na or Mg. Composition explained a mean variability of 77% in antler length and weight. Body weight and size, in turn, influenced mineral composition. The greatest body effect was that of gains during lactation on principal components analysis factor related to Ca, P and other major minerals such as Na, K or Mg. Antler bone composition is variable in normal conditions and such variability may play a role in biomechanical properties of the antler, but it is also likely to show the nutritional status or physiological effort to grow antlers. Assessing bone composition may emerge as a new useful tool to obtain information regarding bone biology and its bearer in other species including ours.

Inverse association between serum selenium concentrations and parameters of immune activation in patients with cardiac disorders

BACKGROUND

As a component of the enzyme glutathione peroxidase, the essential trace element selenium contributes to the reduction of peroxides. Disturbed selenium availability may relate to an activated immune response. In humans, immune activation is reflected by increased neopterin production and accelerated tryptophan degradation, expressed as the kynurenine to tryptophan ratio (kyn/trp). Th1-type cytokine interferon-gamma induces both these immunobiological events in human macrophages and they are often activated in patients with cardiac disorders. The aim of this study was to determine the relationship between serum selenium concentrations and neopterin production and tryptophan degradation in patients with cardiac disorders.

METHODS

In 56 patients (28 females) with cardiac disorders, serum selenium concentrations were determined by graphite-furnace atomic absorption spectrometry. Serum neopterin concentration was measured by ELISA and tryptophan degradation was examined by HPLC.

RESULTS

Selenium concentrations were in the range 0.41-1.90 micromol/L (median 1.02) and were well within the local normal range. Approximately two-thirds of patients presented with higher neopterin concentrations (median 16.4 nmol/L) and tryptophan degradation (median 57 micromol/mmol kyn/trp). There was an inverse correlation between serum selenium and kyn/trp (Spearman's rank correlation, r(s)=-0.431; p<0.001) and neopterin concentrations (r(s)=-0.300; p<0.05). Neopterin concentrations correlated strongly with kyn/trp (r(s)=0.712; p<0.0001).

CONCLUSIONS

A higher degree of tryptophan degradation and of neopterin production in patients with cardiac disorders coincides with lower, albeit still normal, serum selenium concentrations. Data show that in these patients immune activation is associated with lower serum selenium concentrations.

Seasonal and Lactational Changes in Mineral Composition of Milk from Iberian Red Deer (Cervus elaphus hispanicus)

Milk minerals are important for calf growth, and they have other roles as well, such as immune regulation. This 2-yr study examined content of Ca, P, Mg, Na, K, Fe, and Zn in milk of 54 Iberian red deer hinds through 18 wk of lactation. Mean mineral composition of fresh milk was ash = 1.168 +/- 0.007%, Ca = 2,330 +/- 20 mg/kg, P = 640 +/- 10 mg/kg, K = 1,100 +/- 10 mg/kg, Na = 385 +/- 3 mg/kg, Mg = 138 +/- 1 mg/kg, Zn = 12.5 +/- 0.2 mg/kg, and Fe = 0.65 +/- 0.03 mg/kg. All minerals except Mg varied by week of lactation, but variation was usually <10% except for Fe (83% variation) and Zn (30% variation); both of those minerals increased as lactation proceeded. Increased concentrations of Fe and Zn in later lactation compensated for the reduction in milk production in mid and late lactation such that daily production was less variable for Fe (55% variation) or Zn (79% variation) than for other minerals (118 to 135% variation). Potassium content of milk decreased across time, but that effect occurred primarily during the last few weeks of lactation. Calving later vs. early in the calving season had variable effects on concentrations of different minerals: P, Mg, and K concentrations were not affected; Ca, Mg, and Na were all lower in milk from later calving hinds; and both Fe and Zn had higher concentrations in milk from hinds that calved later in the season. Lactating hinds seem to maintain a more stable daily yield of the microminerals Fe and Zn in milk compared with more variable concentrations of macrominerals as lactation progresses. Because of the essential role of Fe and Zn in immune function, a more stable supply of those minerals might be important to the health of growing red deer calves.