Risk assessment for changes in the metabolic profile and body weights of pre-pubertal gilts during long-term monotonic exposure to low doses of zearalenone (ZEN)

Phenotypic, endocrinological, and metabolic effects of zearalenone exposure and additive effect of heat stress in prepubertal female pigs

Independently, both heat stress (HS) and zearalenone (ZEN) compromise female reproduction, thus the hypothesis that ZEN would affect phenotypic, endocrine, and metabolic parameters in pigs with a synergistic and/or additive impact of HS was investigated. Prepubertal gilts (n = 6-7) were assigned to: thermoneutral (TN) vehicle control (TC; n = 6); TN ZEN (40 μg/kg; TZ; n = 6); pair-fed (PF; n = 6) vehicle control (PC; n = 6); PF ZEN (40 μg/kg; PZ; n = 6); HS vehicle control (HC; n = 7); and HS ZEN (40 μg/kg; HZ; n = 7) and experienced either constant 21.0 ± 0.10 °C (TN and PF) or 35.0 ± 0.2 °C (12 h) and 32.2 ± 0.1 °C (12 h) to induce HS for 7 d. Elevated rectal temperature (P < 0.01) and respiration rate (P < 0.01) confirmed induction of HS. Rectal temperature was decreased (P = 0.03) by ZEN. Heat stress decreased (P < 0.01) feed intake, body weight, and average daily gain, with absence of a ZEN effect (P > 0.22). White blood cells, hematocrit, and lymphocytes decreased (P < 0.04) with HS. Prolactin increased (P < 0.01) in PC and PZ and increased in HZ females (P < 0.01). 17β-estradiol reduced (P < 0.01) in HC and increased in TZ females (P = 0.03). Serum metabolites were altered by both HS and ZEN. Neither HS nor ZEN impacted ovary weight, uterus weight, teat size or vulva area in TN and PF treatments, although ZEN increased vulva area (P = 0.02) in HS females. Thus, ZEN and HS, independently and additively, altered blood composition, impacted the serum endocrine and metabolic profile and increased vulva size in prepubertal females, potentially contributing to infertility.

Quercetagetin alleviates zearalenone-induced liver injury in rabbits through Keap1/Nrf2/ARE signaling pathway

Introduction: This study aimed to assess the alleviative effect of quercetagetin (QG) on zearalenone (ZEN)-induced liver injury in rabbits. Methods: Ninety 41-day-old healthy Hyla rabbits were randomly assigned into three groups, including a control (fed with basic diet), ZEN addition group (fed with basic diet + 600 μg/kg ZEN), and ZEN + QG addition group (fed with basic diet + 600 μg/kg ZEN + 100 mg/kg QG), with 30 rabbits per group. The duration of the experiment was 28 days. Results: The results revealed no significant differences in the average daily gain, average daily feed intake, the gain to feed ratio and the liver, kidney and spleen organ indexes (p > 0.05) between the rabbits across the three groups. However, the sacculus rotundus index of the rabbits in the control group was significantly higher than that in the ZEN + QG group (p < 0.05). The intake of ZEN-contaminated diet also significantly increased the activities or levels of alanine transaminase, alkaline phosphatase, total bile acid (TBA), total bilirubin, malondialdehyde, and interleukin-4 (IL-4) and enhanced the abundance of kelch-like ECH-associated protein 1 (Keap1), heat shock protein 70 (HSP70) and cysteine-aspartic acid protease-3 (Caspase-3) mRNA in the blood or liver tissue in ZEN group, compared to the control group (p < 0.05). On the contrary, the activities or levels of immunoglobulin A, complement 3, total antioxidant capacity, glutathione peroxidase (GSH-Px), superoxide dismutase, interleukin-10, and the abundance of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) mRNA were significantly decreased (p < 0.05). Supplementing the diet with QG still maintained significantly higher levels of TBA and IL-4, and the abundance of GSH-Px, HSP70, IL-4, and Caspase-3 mRNA in the blood and liver of rabbits in the ZEN + QG group than in the control group (p < 0.05). At the same time, the other indicators were restored to levels in the control group (p > 0.05). Discussion: In conclusion, QG alleviated the ZEN-induced oxidative damage and liver injury caused by inflammatory reaction through the Keap1-Nrf2-antioxidant response element (ARE) signal pathway, which protected the liver. This study revealed the alleviative effect of QG on the hepatotoxicity of ZEN in rabbits for the first time, providing a new perspective for applying QG and developing a ZEN antidote.

Effect of the Combined Compound Probiotics with Glycyrrhinic Acid on Alleviating Cytotoxicity of IPEC-J2 Cells Induced by Multi-Mycotoxins

Aflatoxins B1 (AFB1), deoxynivalenol (DON) and zearalenone (ZEA) are the three most prevalent mycotoxins, whose contamination of food and feed is a severe worldwide problem. In order to alleviate the toxic effects of multi-mycotoxins (AFB1 + DON + ZEA, ADZ) on inflammation and apoptosis in swine jejunal epithelial cells (IPEC-J2), three species of probiotics (Bacillus subtilis, Saccharomyces cerevisiae and Pseudomonas lactis at 1 × 10⁵ CFU/mL, respectively) were mixed together to make compound probiotics (CP), which were further combined with 400 μg/mL of glycyrrhinic acid (GA) to make bioactive materials (CGA). The experiment was divided into four groups, i.e., the control, ADZ, CGA and ADZ + CGA groups. The results showed that ADZ decreased cell viability and induced cytotoxicity, while CGA addition could alleviate ADZ-induced cytotoxicity. Moreover, the mRNA expressions of IL-8, TNF-α, NF-Κb, Bcl-2, Caspase-3, ZO-1, Occludin, Claudin-1 and ASCT2 genes, and protein expressions of TNF-α and Claudin-1 were significantly upregulated in ADZ group; while the mRNA abundances of IL-8, TNF-α, NF-Κb, Caspase-3, ASCT2 genes, and protein expressions of TNF-α and Claudin-1 were significantly downregulated in the ADZ + CGA group. In addition, the protein expressions of COX-2, ZO-1, and ASCT2 were significantly downregulated in the ADZ group, compared with the control group; whereas CGA co-incubation with ADZ could increase these protein expressions to recover to normal levels. This study indicated that CGA could alleviate cytotoxicity, apoptosis and inflammation in ADZ-induced IPEC-J2 cells and protect intestinal cell integrity from ADZ damages.

The Effect of Low Doses of Zearalenone (ZEN) on the Bone Marrow Microenvironment and Haematological Parameters of Blood Plasma in Pre-Pubertal Gilts

The aim of this study was to determine whether low doses of zearalenone (ZEN) influence the carry-over of ZEN and its metabolites to the bone marrow microenvironment and, consequently, haematological parameters. Pre-pubertal gilts (with a body weight of up to 14.5 kg) were exposed to daily ZEN doses of 5 μg/kg BW (group ZEN5, n = 15), 10 μg/kg BW (group ZEN10, n = 15), 15 μg/kg BW (group ZEN15, n = 15), or were administered a placebo (group C, n = 15) throughout the entire experiment. Bone marrow was sampled on three dates (exposure dates 7, 21, and 42—after slaughter) and blood for haematological analyses was sampled on 10 dates. Significant differences in the analysed haematological parameters (WBC White Blood Cells, MONO—Monocytes, NEUT—Neutrophils, LYMPH—Lymphocytes, LUC—Large Unstained Cells, RBC—Red Blood Cells, HGB—Haemoglobin, HCT—Haematocrit, MCH—Mean Corpuscular Volume, MCHC—Mean Corpuscular Haemoglobin Concentrations, PLT—Platelet Count and MPV—Mean Platelet Volume) were observed between groups. The results of the experiment suggest that exposure to low ZEN doses triggered compensatory and adaptive mechanisms, stimulated the local immune system, promoted eryptosis, intensified mycotoxin biotransformation processes in the liver, and produced negative correlations between mycotoxin concentrations and selected haematological parameters.

Exposure to Zearalenone Leads to Metabolic Disruption and Changes in Circulating Adipokines Concentrations in Pigs

Zearalenone (ZEN) is a mycotoxin classified as an endocrine disruptor. Many endocrine disruptors are also metabolic disruptors able to modulate energy balance and inflammatory processes in a process often involving a family of protein hormones known as adipokines. The aim of our study was to elucidate the role of ZEN as metabolic disruptor in pigs by investigating the changes in energy balance and adipokines levels in response to different treatment diets. To this end, weaned piglets (n = 10/group) were exposed to either basal feed or feed contaminated with 680 and 1620 µg/kg ZEN for 28 days. Serum samples collected at days 7 and 21 were subjected to biochemistry analysis, followed by determination of adipokine levels using a combined approach of protein array and ELISA. Results indicate that ZEN has an impact on lipid and glucose metabolism that was different depending on the dose and time of exposure. In agreement with these changes, ZEN altered circulating adipokines concentrations, inducing significant changes in adiponectin, resistin, and fetuin B. Our results suggest that ZEN may function as a natural metabolism-disrupting chemical.

Survey of zearalenone and type-B trichothecene mycotoxins in swine feed in the USA

New information is needed regarding the types and concentrations of mycotoxins in swine feed. We hypothesized that (1) the mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), nivalenol (NIV), and zearalenone (ZEN) vary among swine ingredient and feed types, and (2) the inclusion of specific ingredients is associated with mycotoxin contamination in complete feed. A total of 707 samples were collected from cooperators in 14 states between June 2018 and January 2020 then analyzed for DON, 3-AcDON, 15-AcDON, NIV, and ZEN contamination using gas chromatography-mass spectrometry (GC-MS). Ninety-four percent (663/707) of samples contained DON, 33% (230/707) of samples contained 3-AcDON, 57% (404/707) of samples contained 15-AcDON, 1% (6/707) of samples contained NIV, and 47% (335/707) of samples contained ZEN. Seventy-three percent (514/707) of samples contained multiple mycotoxins. Resulting DON concentrations were below the national advisory limits for all sample types, and no advisory limits are imposed for the other mycotoxins studied. Increased incorporation of distiller's dried grains with solubles (DDGS) was associated with increased DON in complete feed (R² = 0.82).

The Effects of Mixed Fusarium Mycotoxins at EU-Permitted Feed Levels on Weaned Piglets' Tissue Lipids

At exactly the individual permitted EU-tolerance dietary limits, fumonisins (FB: 5 mg/kg diet) and mixed fusariotoxins (DZ: 0.9 mg deoxynivalenol + 0.1 mg zearalenone/kg diet, and FDZ: 5 mg fumonisins + 0.9 mg deoxynivalenol + 0.1 mg zearalenone/kg diet) were administered to piglets (n = 6/group) for three weeks. Bodyweights of intoxicated piglets increased, while feed conversion ratios decreased. In FDZ, both the absolute and relative weight of the liver decreased. In the renal-cellular membrane, the most pronounced alterations were in FDZ treatment, followed by individual FB exposure. In both treatments, high proportions of C20:0 and C22:0 with low fatty acid (FA) unsaturation were found. In hepatocyte phospholipids, FDZ toxins exerted antagonistic interactions, and FB had the strongest increasing effect on FA monounsaturation. Among all investigated organs, the spleen lipids were the least responsive, in which FDZ expressed synergistic reactions on C20:0 (↑ FDZ vs. FB) and C22:0 (↓ FDZ vs. DZ). The antioxidant defense of the kidney was depleted (↓ glutathione concentration by FB-exposure). Blood plasma indicated renal injury (profound increase of urea and creatinine in FB vs. DZ and FDZ). FB strongly increased total-cholesterol and low density lipoprotein concentrations, whereas FDZ synergistically increased gamma-glutamyltransferase, alkaline-phosphatase, calcium and phosphorus levels. Summarized, individual and combined multiple fusariotoxins modified the membrane lipid profile and antioxidant defense of splanchnic organs, and serum biochemicals, without retarding growth in piglets.

Concentration of Zearalenone, Alpha-Zearalenol and Beta-Zearalenol in the Myocardium and the Results of Isometric Analyses of the Coronary Artery in Prepubertal Gilts

The carry-over of zearalenone (ZEN) to the myocardium and its effects on coronary vascular reactivity in vivo have not been addressed in the literature to date. Therefore, the objective of this study was to verify the hypothesis that low ZEN doses (MABEL, NOAEL and LOAEL) administered per os to prepubertal gilts for 21 days affect the accumulation of ZEN, α-ZEL and β-ZEL in the myocardium and the reactivity of the porcine coronary arteries to vasoconstrictors: acetylcholine, potassium chloride and vasodilator sodium nitroprusside. The contractile response to acetylcholine in the presence of a cyclooxygenase (COX) inhibitor, indomethacin and / or an endothelial nitric oxide synthase (e-NOS) inhibitor, L-NAME was also studied. The results of this study indicate that the carry-over of ZEN and its metabolites to the myocardium is a highly individualized process that occurs even at very low mycotoxin concentrations. The concentrations of the accumulated ZEN metabolites are inversely proportional to each other due to biotransformation processes. The levels of vasoconstrictors, acetylcholine and potassium chloride, were examined in the left anterior descending branch of the porcine coronary artery after oral administration of ZEN. The LOAEL dose clearly decreased vasoconstriction in response to both potassium chloride and acetylcholine (P < 0.05 for all values) and increased vasodilation in the presence of sodium nitroprusside (P = 0.021). The NOAEL dose significantly increased vasoconstriction caused by acetylcholine (P < 0.04), whereas the MABEL dose did not cause significant changes in the vascular response. Unlike higher doses of ZEN, 5 μg/kg had no negative influence on the vascular system.

Zearalenone and the Immune Response

Zearalenone (ZEA) is an estrogenic fusariotoxin, being classified as a phytoestrogen, or as a mycoestrogen. ZEA and its metabolites are able to bind to estrogen receptors, 17β-estradiol specific receptors, leading to reproductive disorders which include low fertility, abnormal fetal development, reduced litter size and modification at the level of reproductive hormones especially in female pigs. ZEA has also significant effects on immune response with immunostimulatory or immunosuppressive results. This review presents the effects of ZEA and its derivatives on all levels of the immune response such as innate immunity with its principal component inflammatory response as well as the acquired immunity with two components, humoral and cellular immune response. The mechanisms involved by ZEA in triggering its effects are addressed. The review cited more than 150 publications and discuss the results obtained from in vitro and in vivo experiments exploring the immunotoxicity produced by ZEA on different type of immune cells (phagocytes related to innate immunity and lymphocytes related to acquired immunity) as well as on immune organs. The review indicates that despite the increasing number of studies analyzing the mechanisms used by ZEA to modulate the immune response the available data are unsubstantial and needs further works.

Effects of Deoxynivalenol and Zearalenone on the Histology and Ultrastructure of Pig Liver

The purpose of this study was to determine the effects of single and combined administrations of deoxynivalenol (DON) and zearalenone (ZEN) on the histology and ultrastructure of pig liver. The study was performed on immature gilts, which were divided into four equal groups. Animals in the experimental groups received DON at a dose of 12 μg/kg body weight (BW) per day, ZEN at 40 μg/kg BW per day, or a mixture of DON (12 μg/kg BW per day) and ZEN (40 μg/kg BW). The control group received vehicle. The animals were killed after 1, 3, and 6 weeks of experiment. Treatment with mycotoxins resulted in several changes in liver histology and ultrastructure, including: (1) an increase in the thickness of the perilobular connective tissue and its penetration to the lobules in gilts receiving DON and DON + ZEN; (2) an increase in the total microscopic liver score (histology activity index (HAI)) in pigs receiving DON and DON + ZEN; (3) dilatation of hepatic sinusoids in pigs receiving ZEN, DON and DON + ZEN; (4) temporary changes in glycogen content in all experimental groups; (5) an increase in iron accumulation in the hepatocytes of gilts treated with ZEN and DON + ZEN; (6) changes in endoplasmic reticulum organization in the hepatocytes of pigs receiving toxins; (7) changes in morphology of Browicz-Kupffer cells after treatment with ZEN, DON, and DON + ZEN. The results show that low doses of mycotoxins used in the present study, even when applied for a short period, affected liver morphology.

Acute Exposure to Zearalenone Disturbs Intestinal Homeostasis by Modulating the Wnt/β-Catenin Signaling Pathway

The mycotoxin zearalenone (ZEN), which frequently contaminates cereal-based human food and animal feed, is known to have an estrogenic effect. The biological response associated with exposure to ZEN has rarely been reported in organs other than the reproductive system. In the intestine, several studies suggested that ZEN might stimulate molecular changes related to the activation of early carcinogenesis, but the molecular mechanisms behind these events are not yet known. In this study, we investigated gene expression and changes in protein abundance induced by acute exposure to ZEN in the jejunum of castrated male pigs using an explant model. Our results indicate that ZEN induces the accumulation of ERα but not ERβ, modulates Wnt/β-catenin and TGF-β signaling pathways, and induces molecular changes linked with energy sensing and the antimicrobial activity without inducing inflammation. Our results confirm that the intestine is a target for ZEN, inducing changes that promote cellular proliferation and could contribute to the onset of intestinal pathologies.

Reproductive Performance of Mares Fed Dietary Zearalenone

It is known that zearalenone (ZON) interacts directly with estrogen receptors, and its in vivo effects on reproduction have been well-documented in several species. In contrast, reports of ZON's impact on horse reproduction are conflicting and inconclusive, some studies confounded by the presence of mycotoxins such as deoxynivalenol in the feed. This study assesses the effect of chronic consumption of zearalenone on reproduction in cycling mares fed >95% pure ZON (0, 2, or 8 mg/da; n = 7 mares/treatment) for three estrous cycles, followed by artificial insemination, through 16 days of pregnancy. Animals were on ZON treatment for between 70 and 121 days (average 84) depending on individual cycle patterns. ZON-induced changes in serum concentration of estradiol (E₂) and progesterone (P₄), and total estrogenicity were measured using RIAs and the E-screen assay, respectively. Effects on reproductive physiology and pregnancy were monitored by ultrasound and clinical parameters. No significant changes were found in reproductive hormone levels of E₂, or P₄ for mares on ZON treatments compared to controls, although there was a significant (P < 0.01) increase in P₄ levels across Cycle number in High ZON (8 mg/da) treated mares. There was also an increasing trend in the interovulatory interval in the High ZON treatment group. The overall estrogenicity was similar across treatments and over time, not differing from controls or between ZON treatment groups. Adverse uterine and ovarian effects were also not observed, but pregnancy rates were mixed with only 4 of 7 mares on Low ZON becoming pregnant, and only 3 maintaining pregnancy and fetal heartbeat by Day 30, compared to 5 of 6 control mares and all 7 mares on High ZON. Because reproductive efficiency and hormone concentrations are highly variable across individuals, this study did not demonstrate that ZON at 2 or 8 mg/da was detrimental to mares' reproduction. Yet, inferring that ZON treatments were completely without effect is also not appropriate, as the absence of measurable significant differences could be attributed to the limited sample size. Most importantly, there were no extreme signs of toxicology, in contrast to previous reports when ZON was fed at these "doses."

MicroRNAs in porcine uterus and serum are affected by zearalenone and represent a new target for mycotoxin biomarker discovery

The mycotoxin zearalenone (ZEN) poses a risk to animal health because of its estrogenic effects. Diagnosis of ZEN-induced disorders remains challenging due to the lack of appropriate biomarkers. In this regard, circulating microRNAs (small non-coding RNAs) have remarkable potential, as they can serve as indicators for pathological processes in tissue. Thus, we combined untargeted and targeted transcriptomics approaches to investigate the effects of ZEN on the microRNA expression in porcine uterus, jejunum and serum, respectively. To this end, twenty-four piglets received uncontaminated feed (Control) or feed containing 0.17 mg/kg ZEN (ZEN low), 1.46 mg/kg ZEN (ZEN medium) and 4.58 mg/kg ZEN (ZEN high). After 28 days, the microRNA expression in the jejunum remained unaffected, while significant changes in the uterine microRNA profile were observed. Importantly, 14 microRNAs were commonly and dose-dependently affected in both the ZEN medium and ZEN high group, including microRNAs from the miR-503 cluster (i.e. ssc-miR-424-5p, ssc-miR-450a, ssc-miR-450b-5p, ssc-miR-450c-5p, ssc-miR-503 and ssc-miR-542-3p). Predicted target genes for those microRNAs are associated with regulation of gene expression and signal transduction (e.g. cell cycle). Although the effects in serum were less pronounced, receiver operating characteristic analysis revealed that several microRNA ratios were able to discriminate properly between non-exposed and ZEN-exposed pigs (e.g. ssc-miR-135a-5p/ssc-miR-432-5p, ssc-miR-542-3p/ssc-miR-493-3p). This work sheds new light on the molecular mechanisms of ZEN, and fosters biomarker discovery.

The effect of subchronic oral exposure to zearalenone on hematologic and biochemical analytes, and the blood redox status of adult rabbit bucks

BACKGROUND

Zearalenone (ZEN) is a mycoestrogen with a ubiquitous presence in animal feeds, which also has hematotoxic, hepatotoxic, nephrotoxic, and immunotoxic properties. However, there is a paucity of literature that discusses the effects of ZEN on rabbits.

OBJECTIVES

The aim of this study was to evaluate the effect of a prolonged, low-level (50 μg ZEN/kg body weight) exposure on the clinicopathologic and redox status analytes of rabbit bucks.

METHODS

Ten adult bucks were included in the study. Each underwent a 7-week control period, followed by a 7-week exposure period. Water or ZEN solutions were daily administered orally (0.5 mL) during the control and exposure periods, respectively. Blood samples were collected weekly for Complete Blood Counts, serum biochemical analyte and reactive oxygen metabolite (ROM) measurements. Data were analyzed using a mixed model, and the level of significance was set at a P of <0.05.

RESULTS

During the ZEN exposure period, significant increases were noted in the red blood cell distribution width (RDW) and mean platelet volumes (MPVs), as well as in the white blood cell, monocyte, and eosinophil counts. Significant increases were observed in aspartate aminotransferase and total bilirubin, whereas urea, creatinine, glucose, total calcium, sodium, and potassium concentrations were significantly decreased. The ROM concentrations did not differ significantly between the control and ZEN exposure periods.

CONCLUSIONS

Under the present experimental conditions, ZEN affected some of the clinicopathologic analytes of adult rabbit bucks; these changes were mostly indicative of mild hepatocellular damage and dysfunction, inflammatory and/or allergic responses, and renal tubular damage. A ZEN dose of 50 μg/kg body weight did not seem to affect the blood redox status of bucks, as evaluated by the ROM concentrations.

Current challenges in the diagnosis of zearalenone toxicosis as illustrated by a field case of hyperestrogenism in suckling piglets

Background

The mycotoxin zearalenone (ZEN) causes functional and morphological alterations in reproductive organs of pigs. In the field, diagnosis of ZEN-induced disorders is often challenging, as relevant feed lots are no longer available, or feed analysis results are not conclusive. Here, we report a field case of hyperestrogenism in newborn piglets. Surprisingly, more than 50 fungal metabolites were detected in hay pellets fed to gestating sows, including ZEN and its modified form zearalenone-14-sulfate (ZEN-14-S). Despite the broad contamination range in this unconventional feed component, a definite diagnosis of mycotoxicosis could not be achieved. In this context, current limitations regarding the confirmation of suspected cases of ZEN-induced disorders are discussed, covering both feed analysis and the biomarker approach.

Case presentation

A piglet producer with 200 sows experienced a sudden increase in suckling piglet losses up to 30% by lower vitality and crushing. Predominant clinical signs were splay legs and signs of hyperestrogenism such as swollen and reddened vulvae in newborn piglets. The first differential diagnosis was ZEN mycotoxicosis although feed batches had not been changed for months with the exception of ground hay pellets, which had been included in the diet five months before. Analysis of hay pellets resulted in a sum value of ZEN and its modified forms of more than 1000 μg/kg, with ZEN-14-S alone accounting for 530 μg/kg. Considering the inclusion rate of 7% in the diet for gestating sows, the severe impact of the additional ZEN load due to the contaminated hay pellets seemed unrealistic but could not be completely excluded either. One month after hay pellets had been removed from the diet no further clinical signs were observed.

Conclusions

Enrichment materials and other fibre sources can contain significant amounts of mycotoxins and should be therefore included in feed analysis. Adequate methods for broad spectrum mycotoxin determination, including modified mycotoxins, are important. As highlighted by this field case, there is a need to establish reliable biomarkers for ZEN exposure in pigs. Currently, available biomarkers do not allow a solid prediction of the ZEN intake of pigs under field conditions, which limits their application to experimental studies.

Growth performance, selected blood biochemical parameters and body weights of pre-pubertal gilts fed diets supplemented with different doses of zearalenone (ZEN)

The aim of this study was to determine whether exposure to low doses of zearalenone (ZEN) induces changes in the serum biochemical profile and body weights (BW). Pre-pubertal gilts (with BW of up to 14.5 kg) were administered ZEN in daily doses of 5 μg/kg BW (group 1, n = 15), 10 μg/kg BW (group 2, n = 15), 15 μg/kg BW (group 3, n = 15) or placebo (control group C, n = 15) throughout the experiment. Blood was sampled for analysis on 10 dates (at five-day intervals). Minor but statistically significant differences in the analysed serum biochemical parameters (ALT, AST, ALP, total cholesterol, total bilirubin, glucose, total protein, iron, BUN and urea) were observed in the studied groups. The biochemical parameters of the analysed gilts indicate that the maintenance of homeostasis and biotransformation of ZEN require considerable energy expenditure. Beginning on the fourth analytical date, BW gains were consistently higher in the experimental groups than in group C. The observed decrease in glucose and total protein levels can probably be attributed to higher BW gains and the ongoing ZEN biotransformation processes in the enterocytes and the liver.

Mycotoxin: Its Impact on Gut Health and Microbiota

The secondary metabolites produced by fungi known as mycotoxins, are capable of causing mycotoxicosis (diseases and death) in human and animals. Contamination of feedstuffs as well as food commodities by fungi occurs frequently in a natural manner and is accompanied by the presence of mycotoxins. The occurrence of mycotoxins' contamination is further stimulated by the on-going global warming as reflected in some findings. This review comprehensively discussed the role of mycotoxins (trichothecenes, zearalenone, fumonisins, ochratoxins, and aflatoxins) toward gut health and gut microbiota. Certainly, mycotoxins cause perturbation in the gut, particularly in the intestinal epithelial. Recent insights have generated an entirely new perspective where there is a bi-directional relationship exists between mycotoxins and gut microbiota, thus suggesting that our gut microbiota might be involved in the development of mycotoxicosis. The bacteria-xenobiotic interplay for the host is highlighted in this review article. It is now well established that a healthy gut microbiota is largely responsible for the overall health of the host. Findings revealed that the gut microbiota is capable of eliminating mycotoxin from the host naturally, provided that the host is healthy with a balance gut microbiota. Moreover, mycotoxins have been demonstrated for modulation of gut microbiota composition, and such alteration in gut microbiota can be observed up to species level in some of the studies. Most, if not all, of the reported effects of mycotoxins, are negative in terms of intestinal health, where beneficial bacteria are eliminated accompanied by an increase of the gut pathogen. The interactions between gut microbiota and mycotoxins have a significant role in the development of mycotoxicosis, particularly hepatocellular carcinoma. Such knowledge potentially drives the development of novel and innovative strategies for the prevention and therapy of mycotoxin contamination and mycotoxicosis.

Risks for animal health related to the presence of zearalenone and its modified forms in feed

Zearalenone (ZEN), a mycotoxin primarily produced by Fusarium fungi, occurs predominantly in cereal grains. The European Commission asked EFSA for a scientific opinion on the risk to animal health related to ZEN and its modified forms in feed. Modified forms of ZEN occurring in feed include phase I metabolites α‐zearalenol (α‐ZEL), β‐zearalenol (β‐ZEL), α‐zearalanol (α‐ZAL), β‐zearalanol (β‐ZAL), zearalanone (ZAN) and phase II conjugates. ZEN has oestrogenic activity and the oestrogenic activity of the modified forms of ZEN differs considerably. For ZEN, the EFSA Panel on Contaminants in the Food Chain (CONTAM) established no observed adverse effect levels (NOAELs) for pig (piglets and gilts), poultry (chicken and fattening turkeys), sheep and fish (extrapolated from carp) and lowest observed effect level (LOAEL) for dogs. No reference points could be established for cattle, ducks, goats, horses, rabbits, mink and cats. For modified forms, no reference points could be established for any animal species and relative potency factors previously established from rodents by the CONTAM Panel in 2016 were used. The dietary exposure was estimated on 17,706 analytical results with high proportions of left‐censored data (ZEN about 60%, ZAN about 70%, others close to 100%). Samples for ZEN were collected between 2001 and 2015 in 25 different European countries, whereas samples for the modified forms were collected mostly between 2013 and 2015 from three Member States. Based on exposure estimates, the risk of adverse health effects of feed containing ZEN was considered extremely low for poultry and low for sheep, dog, pig and fish. The same conclusions also apply to the sum of ZEN and its modified forms.

Activity of Zearalenone in the Porcine Intestinal Tract

This study demonstrates that low doses (somewhat above the No Observed Adverse Effect Level, NOAEL) of the mycoestrogen zearalenone (ZEN) and its metabolites display multispecificity towards various biological targets in gilts. The observed responses in gilts were surprising. The presence of ZEN and zearalenols (ZELs) did not evoke a response in the porcine gastrointestinal tract, which was attributed to dietary tolerance. Lymphocyte proliferation was intensified in jejunal mesenteric lymph nodes, and lymphocyte counts increased in the jejunal epithelium with time of exposure. In the distal digestive tract, fecal bacterial counts decreased, the activity of fecal bacterial enzymes and lactic acid bacteria increased, and cecal water was characterized by higher genotoxicity. The accompanying hyperestrogenism led to changes in mRNA activity of selected enzymes (cytochrome P450, hydroxysteroid dehydrogenases, nitric oxide synthases) and receptors (estrogen and progesterone receptors), and it stimulated post-translational modifications which play an important role in non-genomic mechanisms of signal transmission. Hyperestrogenism influences the regulation of the host's steroid hormones (estron, estradiol and progesteron), it affects the virulence of bacterial genes encoding bacterial hydroxysteroid dehydrogenases (HSDs), and it participates in detoxification processes by slowing down intestinal activity, provoking energy deficits and promoting antiporter activity at the level of enterocytes. In most cases, hyperestrogenism fulfils all of the above roles. The results of this study indicate that low doses of ZEN alleviate inflammatory processes in the digestive system, in particular in the proximal and distal intestinal tract, and increase body weight gains in gilts.

Changes in the metabolic profile and body weight of pre-pubertal gilts during prolonged monotonic exposure to low doses of zearalenone and deoxynivalenol

The aim of this study was to determine whether exposure to low doses of ZEN + DON induces changes in serum biochemical and hematological parameters in pre-pubertal gilts. In the evaluated groups, minor but statistically significant changes were noted in selected serum biochemical parameters, including glucose, total cholesterol, ALT, AST, AP, total bilirubin, P_in, Fe, K and Cl, and in hematological parameters, including WBC, eosinophils, basophils, monocytes, Ht, Hb, MCHC, HDW and PLT. A statistical analysis of the results revealed significant differences between groups in the values of WBC, eosinophils, basophils, Hb, Ht, PLT, glucose, ALT, AP, total bilirubin, Fe and K. Change trends were noted mainly in weeks II and V-VI. An analysis of the metabolic profile of pre-pubertal gilts exposed to ZEN + DON indicates that homeostasis and biotransformation of ZEN + DON can be toned down at the expense of the animals' energy reserves. Body weight gains were lower in group E, and BW gains were not observed in weeks II and VI. The activity levels of gilts decreased in the first weeks of exposure (I and II), but the drop was minimized by a compensatory effect, or in the last two weeks of exposure due to nutrient deficiency or insufficient supply of protein and energy with feed and feed additives, which decreased BW gains. Low doses of mycotoxins induce completely different changes in the metabolic test than higher doses. The above can probably be attributed to: (i) a negative compensatory effect, (ii) initiation of adaptive mechanisms and stimulation of the immune system, probably due to the allergizing properties of mycotoxins, (iii) excessive loss of energy and protein due to more effective feed utilization, or (iv) involvement in detoxification processes which leads to fatigue. Depending on the body's energy stores, the above processes tend to tone down the biotransformation of low doses of the examined mycotoxins but in the present study, the BW of gilts did not increase under exposure to a combination of ZEN + DON.