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 Modified Palygorskite Supplementation on Egg Quality and Mineral Element Content, and Intestinal Integrity and Barrier Function of Laying Hens

This study was conducted to investigate effects of modified palygorskite (MPal) supplementation on the laying performance, egg quality and mineral element content, immunity, oxidative status, and intestinal integrity and barrier function of laying hens. A total of 360 52-week-old Hyline Brown hens were randomly assigned into four dietary treatments for a 7-week feeding trial. The birds were fed a basal diet supplemented with 0 (control group), 0.25, 0.5, and 1 g/kg MPal, respectively. The supplementation of MPal did not alter laying performance and egg quality among groups. Compared with the control group, MPal inclusion decreased lead (Pb) content in yolks at 49 days, and either 0.5- or 1-g/kg MPal supplementation decreased Pb accumulation in yolks at 25 days and manganese (Mn) accumulation in yolks at 25 and 49 days. The contents of jejunal secretory immunoglobulin A (SIgA), ileal SIgA, and immunoglobulin G were decreased by the dietary 0.5-g/kg MPal supplementation. The supplementation of MPal also decreased malondialdehyde content in jejunum and ileum, and decreased serum diamine oxidase activity of the laying hens at 25 and 49 days. The inclusion of 0.5 and 1 g/kg MPal enhanced villus height in jejunum and ileum, and also increased the ratio of villus height to crypt depth in ileum. In conclusion, MPal supplementation decreased Pb and Mn contents in yolks, and exhibited beneficial effects on the intestinal immunity, oxidative status, and intestinal integrity and barrier function of laying hens and its optimal dosage was 0.5 g/kg.

Effects of different levels of modified palygorskite supplementation on the growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers

This experiment was designed to investigate effects of different levels of modified palygorskite (MPal) supplementation on growth performance, immunity, oxidative status and intestinal integrity and barrier function of broilers. A total of 320 1-day-old Arbor Acres broilers were randomly assigned into 5 dietary treatments and fed a basal diet supplemented with 0, 0.25, 0.5, 1 and 2 g/kg MPal, respectively, for a 42-day feeding trial. Treatments quadratically reduced feed/gain ratio (F:G) during 1-21 days and linearly decreased average daily feed intake and F:G during 22-42 days, and linearly and quadratically decreased average daily feed intake and F:G during overall period (p < 0.05, 0.50 g/kg treatment showed the lowest F:G). MPal supplementation increased the contents of 21-day jejunal secretory immunoglobulin A (SIgA) quadratically, and 21-day jejunal immunoglobulin G (IgG), immunoglobulin M (IgM) and 42-day jejunal total superoxide dismutase (T-SOD) activity linearly and quadratically (0.50 g/kg treatment showed the highest immunoglobulin concentration), whereas linearly reduced 21-day ileal SIgA level and 42-day jejunal malondialdehyde (MDA) accumulation and serum diamine oxidase activity, and quadratically decreased 21-day ileal MDA level (p < 0.05). The 42-day jejunal SIgA, IgG and IgM concentrations, and T-SOD activity in jejunum at 21 days and ileum at both 21 days and 42 days were quadratically increased with MPal administration (p < 0.05, 0.50 g/kg treatment showed the highest T-SOD activity). The mucin 2 mRNA abundances in 42-day jejunum and 21-day ileum were quadratically increased with MPal supplementation (p < 0.05). Treatments linearly increased 42-day ileal zonula occludens-1, claudin-3 and jejunal claudin-3 mRNA level, whereas linearly and quadratically increased ileal claudin-2 mRNA level (p < 0.05). In conclusion, MPal supplementation exhibited beneficial effects on growth performance, intestinal immunity, antioxidant capacity and intestinal integrity and barrier function of broiler with its optimum dosage being 0.5 g/kg.

Efficacy of feed additives to reduce the effect of naturally occurring mycotoxins fed to turkey hen poults reared to 6 weeks of age

Corn with naturally occurring aflatoxin (AF), wheat with naturally occurring doxynivalenol (DON), and barley with naturally occurring zearalenone (ZEA) were used to make rations for feeding turkey hen poults to 6 weeks of age. Control rations with equal amounts of corn, wheat, and barley were also fed. The control rations did contain some DON while both sets of rations contained ZEA. Within each grain source, there were 4 treatments: the control ration plus 3 rations each with a different feed additive which were evaluated for the potential to lessen potential mycotoxin effects on bird performance and physiology. The additives were Biomin BioFix (2 lb/ton), Kemin Kallsil (4 lb/ton), and Nutriad UNIKE (3 lb/ton). The mycotoxin rations reduced poult body weight (2.31 vs. 2.08 ± 0.02 kg) and increased (worsened) poult feed conversion (1.47 vs. 1.51 ± 0.01) at 6 wk. Feeding the poults the mycotoxin feed also resulted in organ and physiological changes typical of feeding dietary aflatoxin although a combined effect of AF, DON, and ZEA which cannot be dismissed. The feed additives resulted in improved feed conversion to 6 wk in both grain treatment groups. The observed physiological effect of feeding the additives was to reduce relative gizzard weight for both groups and to lessen the increase in relative kidney weight for the birds fed the mycotoxin feed. In conclusion, the feed additives used in this study did alleviate the effect of dietary mycotoxins to some degree, especially with respect to feed conversion. Further studies of longer duration are warranted.

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.

Excretion kinetics and metabolism of zearalenone in broilers in dependence on a detoxifying agent

Two experiments were carried out with male broilers to examine excretion kinetics of zearalenone (ZON) and its metabolites and their occurrence in blood plasma and bile fluid after a single oral dose of ZON (approximately 6 micrograms/kg BW) from naturally contaminated wheat (406 micrograms ZON per kg). In addition, this ZON bolus was administered either in the absence or presence of a detoxifying agent (Mycofix-Plus, Biomin GmbH, Herzogenburg, Austria). Specimens were sampled after administration of the zearalenone bolus at different times of up to 48 h. Excretion of zearalenone and alpha-zearalenol as the only detectable metabolite of ZON peaked at approximately 6.5 h after administration of the bolus. Cumulative excretion of both substances amounted to approximately 58% of ZON intake after 48 h, when a plateau was achieved. The incomplete recovery could have been due to a partial total degradation of ZON in the digestive tract, undetected sulfate conjugates of ZON or its metabolites, to other unknown and undetected metabolites or to incomplete analytical recovery from the matrix, and needs to be examined further. Peak concentrations of zearalenone and alpha-zearalenol in bile were detected in the time period of approximately 2 to 6 h after bolus, whereas ZON and metabolite concentrations in blood plasma were around or lower than the detection limits. Mycofix-Plus supplementation seemed to have only minor or no effects on the parameters examined.

Micotoxinas e Micotoxicoses na Avicultura

Esta revisão tem como objetivo principal mostrar, baseado em dezenas de pesquisas realizadas, os efeitos tóxicos das micotoxinas aflatoxinas, tricotecenos, zealenona e fumonisinas sobre o desempenho das aves. O descobrimento das propriedades hepatotóxicas e hepatocarcinogênicas de algumas linhagens de Aspergillus flavus e A. parasiticus em perus, na Inglaterra, no início da década de 1960, seguida pela elucidação da estrutura de seus metabólitos tóxicos, as aflatoxinas, deu novo enfoque e prioridade para a pesquisa sobre micotoxinas. Análises de aflatoxinas realizadas no Laboratório de Análises Micotoxicológicas (LAMIC) da Universidade Fedaral de Santa Maria, entre os anos de 1986 e janeiro de 2000, em 15.600 amostras de alimentos destinados principalmente ao consumo animal, demonstram que no milho analisado, 41,9% das amostras estavam contaminadas por aflatoxinas. Em surtos de aflatoxicose no campo, uma das características mais marcantes é a má absorção que se manifesta como partículas de ração mal digeridas na excreta das aves. Também observa-se, em frangos e poedeiras que recebem AFL, extrema palidez das mucosas e pernas. Dietas deficientes em riboflavina ou colecalciferol (vit. D) tornaram frangos sensíveis, nos índices de desenvolvimento corporal, a concentrações muito baixas de AFL. O efeito aflatoxina nos frangos é maior na fase inicial de crescimento, ou seja, quando as aves ingeriram aflatoxina nos primeiros 21 dias de vida, e quanto maior o nível de stress do lote, menor a quantidade de AFL para afetar negativamente seu desempenho, seja na produção de carne ou de ovos. As principais micotoxinas do grupo dos tricotecenos são: toxina T-2; deoxynivalenol (DON); diacetoxyscirpenol (DAS), todas produzidas através de diversas espécies de fungos do gênero Fusarium. Além dos tricotecenos, o fusarium também pode produzir zearalenona e fumonisinas. Dessas fusarium-toxinas, somente toxina T-2 gera patologias sérias nas aves, como lesões orais e imunodepressão. As fumonisinas afetam o desempenho de frangos de corte a partir de uma ingestão de 75 ppm. Já zearalenona e DON são inócuas quando ingeridas por aves. Para o controle de contaminação de micotoxinas nos alimentos, o melhor método é prevenir o crescimento de fungos, apertando-se no controle de qualidade da matéria prima. Métodos alternativos podem ser usados, utilizando-se antifúngicos ou adsorventes na ração. O monitoramento dos grãos recebidos ou a receber é o ponto fundamental num programa de controle de micotoxinas. Isso deve ser feito através de um programa amostral consistente da massa de grãos recebida ou a ser adquirida, com análises periódicas das micotoxinas.

The metabolism of zearalenone in subcellular fractions from rabbit and hen hepatocytes and its estrogenic activity in rabbits

The in vitro reduction of zearalenone (ZEN) by subcellular fractions from hen and rabbit hepatocytes clearly shows species-specific differences in the cofactor requirements, rate of metabolism and production of metabolites. The presence of NADH as cofactor in the reaction mixtures enhanced only the reducing activity of the microsomal fraction from rabbit hepatocytes, while NADPH enhanced the reducing activities of the cytosolic fraction from rabbit and both the microsomal and cytosolic fractions from hen hepatocytes. Furthermore, we observed that hen hepatocytes metabolize faster and produce beta-zearalenol (ZEL) as the major metabolite, whereas rabbit hepatocytes metabolize ZEN slowly and mainly into alpha-ZEL, the more uterotrophic metabolite. These last findings are closely related to the higher sensitivity to ZEN estrogenic effects observed in rabbits during the toxicity test involving p.o. administration of the mycotoxin to the animals at 3 dosage levels (0.1, 1, 2 mg/kg body wt).

Metabolism of high concentrations of dietary zearalenone by young male turkey poults

Six male turkey poults (3 weeks of age) were fed a starter ration artificially contaminated with 800 mg zearalenone/kg for a 2-week period to examine zearalenone metabolism and residues in various tissues, excreta, and blood plasma. Zearalenone had no effect on either feed consumption or body weight gain. All the birds fed zearalenone frequently showed strutting behavior, displayed an increased size and coloration of caruncles and dewlaps, and had swollen vent tissue. None of these signs were seen among six control birds fed uncontaminated starter feed. Hormone analysis, however, revealed that the testosterone concentrations in blood plasma were the same in both controls and treated birds. Analysis after 14 days of feeding showed that most of the dietary zearalenone had been metabolized into alpha-zearalenol. Levels of zearalenone and alpha-zearalenol were: blood plasma 66 +/- 27 and 194 +/- 80 ng/ml, excreta 182 +/- 33 and 644 +/- 86 micrograms/g, lung 56 +/- 45 and 202 +/- 161 ng/g, heart 57 +/- 40 and 238 +/- 121 ng/g, kidney 122 +/- 25 and 477 +/- 53 ng/g, and liver 276 +/- 54 and 2715 +/- 590 ng/g, respectively. Only traces of beta-zearalenol could be detected in plasma, excreta, and the various tissues. The percentage alpha-zearalenol of total zearalenone plus alpha-zearalenol rose significantly in both blood plasma and excreta during the experimental period. Almost all zearalenone and alpha-zearalenol was found conjugated in blood plasma, and the conjugates consisted of both glucuronides and sulfate conjugates. Approximately 65% of all zearalenone and alpha-zearalenol in excreta was found to be conjugated.

Liver lipid levels in White Leghorn hens fed diets that contained wheat contaminated by deoxynivalenol (vomitoxin)

Three genotypes of White Leghorn hens were fed diets containing either clean wheat (less than .02 ppm deoxynivalenol in diet) or deoxynivalenol (vomitoxin) contaminated wheat (.35 or .70 ppm deoxynivalenol in diet) for 86 or 135 days. Lipid analyses indicated that the percent total lipid and the triglyceride content of livers from birds receiving the vomitoxin contaminated diets were significantly higher than for birds receiving the clean diet. However, the livers of birds receiving the .35 ppm diet had the highest percent total lipid and triglycerides. Livers from control birds contained 11.5% total lipid with 420 mg triglyceride per liver; livers from the .35 ppm birds had 16.7% total lipid, 785 mg triglyceride; livers from the .70 ppm birds had 13.4% total lipid, 548 mg triglyceride. Liver phospholipid content did not appear to be affected by the deoxynivalenol content of the diet. Both genotype and level of vomitoxin in the diet significantly affected liver cholesterol levels.

High tolerance of broilers to vomitoxin from corn infected with Fusarium graminearum

Corn purposely infected with Fusarium graminearum was found to contain 800 to 900 mg vomitoxin/kg. Contaminated corn was substituted for control corn at 0, 6, 12, 18, and 24% in a corn-soybean meal ration. Broiler cockerels were given each experimental diet from 6 to 11 days of age; then sample groups were necropsied. Remaining birds were subsequently offered commercial starter for 2 days and sample groups again necropsied. Growth and diet consumption were not significantly reduced until contaminated corn exceeded 12% of the ration (116 mg vomitoxin/kg). Alertness, coordination, and feathering appeared normal regardless of treatment. Birds that received contaminated corn exhibited plaques in the mouth and gizzard erosions proportional to the level of substitution. All lesions were generally restricted to the epithelial layer and no liver or kidney involvement could be demonstrated. A short return to uncontaminated feed eliminated most lesions. Fowl appear to be considerably more tolerant of vomitoxin than swine.

A high pressure liquid chromatographic method for the analysis of zearalenone in chicken blood

A high pressure liquid chromatographic (HPLC) method is described to determine zearalenone in chicken blood. Samples are extracted with acetonitrile, followed by a hexane cleanup procedure and extracted further with ethyl acetate. The analysis of zearalenone is by HPLC using a reverse phase radial compression separation system, an ultraviolet absorbance detector and a mobile phase of acetonitrile-water 60:40 (v/v). Recoveries of zearalenone in blood at levels of 50-200 ng/ml are in the range of 66.8-72.6%.

Effect of dietary zearalenone on reproduction of chickens

Variable quantities of zearalenone (0, 10, 25, 50, 100, 200, 400, or 800 mg/kg diet) were incorporated into a practical laying hen diet and fed to 30-week-old White Leghorn females in egg production. During the 3 week pretest and 8 week experimental periods hens were inseminated weekly with .05 ml of pooled semen from males fed normal diets. Zearalenone was without effect on egg production, egg size, feed consumption, change in body weight, fertility, hatchability of fertile eggs, growth of progeny to 3 weeks of age, comb, weight, oviduct weight, heart weight, liver weight, spleen weight, egg shell thickness, Haugh units, blood hematology, serum calcium, serum inorganic phosphorus, and serum alkaline phosphatase. Zearalenone above 50 mg/kg of diet caused reduced serum cholesterol. In a reciprocal study, adult male New Hampshire chickens were fed diets containing 0, 100, or 800 mg/kg zearalenone for an 8 week period. Semen was collected and inseminated into White Leghorn females fed normal diets. Zearalenone was without effect on fertility or hatch of fertile eggs resulting from matings of these males. Zearalenone resulted in reduced serum inorganic phosphorus, serum cholesterol, and serum alkaline phosphatase in males. Histological examination of a number of tissues in both males and females revealed no changes due to zearalenone feeding. It is concluded that zearalenone up to 800 mg/kg of diet is without effect on reproductive performance of mature chickens.

Effects of dietary zearalenone on finishing broiler chickens and young turkey poults

A total of 168 broiler chickens (6 to 9 weeks of age) and 192 turkey poults (3-1/2 to 6-1/2 weeks of age) were fed purified zearalenone at levels of 0 (control), 10, 25 (turkeys only), 50, 100, 200, 400, and 800 mg/kg diet for a 3 week period to evaluate its toxicity. Dietary zearalenone had no effect on body weight gain, feed consumption, weights of liver, heart, spleen, and bursa of Fabricius, serum calcium, phosphorus, alkaline phosphatase, total protein and cholesterol, hematocrit, hemoglobin, red blood cell count, white blood cell count, and differential leukocyte count in both chickens and turkeys. Male broiler comb and testes weights were reduced by high levels of zearalenone. Female comb weight, broiler oviduct weight, and turkey testes and ovaries were unaffected by zearalenone. Histopathological examination of tissues revealed no change due to zearalenone. Male turkeys fed 400 and 800 mg/kg zearalenone had increased development of dewlaps and caruncles and exhibited considerable strutting behavior. Muscle and fat tissue from broilers fed 800 mg/kg zearalenone had no detectable estrogenic activity as measured by mouse uterine bioassay. These studies indicate that the effects of dietary zearalenone on finishing broilers and young growing turkey poults are minimal.