Aflatoxicol and aflatoxins B1 and M1 in eggs and tissues of laying hens consuming aflatoxin-contaminated feed

Aflatoxin B1 in the egg chain: monitoring with specific indirect competitive ELISA in northern Paraná, Brazil

An indirect competitive immunoassay (ic-ELISA) was developed using monoclonal antibody produced by hybridoma AF4, which showed high specificity and reactivity with aflatoxin B1 (AFB1) and aflatoxicol, but low cross-reactivity to other analogs. This low cost reliable method was applied for AFB1 monitoring in the poultry chain of a high agribusiness potential region (northern Paraná state, Brazil). Maize, laying hens feed and egg samples were collected from two poultry farms (with production above 200,000 eggs/day) and evaluated by intralaboratory validated ic-ELISA. The sensitivity of such a validated assay, detecting picogram levels of aflatoxins, demonstrated to be proper for surveying daily ingested cumulative toxins and estimating risks. Additionally, more than 61.00% of positive egg samples ranged between the limit of quantification (LOQ – 0.035 ng/g) and 1.00 ng/g, values commonly not covered by commercial kits. Positive data (>LOQ) occurred in 22 maize (56.40%), 34 feed (85.00%) and 192 (48.00%) egg samples. Mean contamination in maize was 1.51±0.94 ng/g (range 0.11-3.91 ng/g), 1.26±0.96 ng/g in feed (0.10-3.58 ng/g), and 1.01±0.77 ng/g in egg (0.05-3.85 ng/g). No statistical difference was observed between farms (P>0.05) for any of the matrices analysed. However, the difference between median values in maize (0.98 ng/g – Farm A; 1.76 ng/g – Farm B) indicated a higher contamination trend in farm B, possibly due to inadequate local storage. Although there is no limit stipulated for AFB1 contamination in eggs, the levels detected in samples were low and do not represent an immediate risk to animal production or human consumption. Nevertheless, the high frequency of positive maize and feed samples in this field of agribusiness should be highlighted. Sensitive aflatoxin monitoring procedures must be strategically carried out from raw materials to animal derived products, aiming harmless production, which also assures human health.

Nrf2: a main responsive element in cells to mycotoxin-induced toxicity

Nuclear factor erythroid 2-like 2 (Nrf2) is a transcription factor participating in response to cellular oxidative stress to maintain the redox balance. Generation of reactive oxygen species (ROS) and, in consequence, oxidative stress, are physiological as well as pathological processes which take place in almost all types of cells. Nrf2, in response to oxidative stress, activates expression and production of antioxidant enzymes to remove free radicals. However, the role of Nrf2 seems to be more sophisticated and its increased expression observed in cancer cells allows to draw a conclusion that its role is tissue—and condition—dependent. Interestingly, Nrf2 might also play a crucial role in response to environmental factors like mycotoxins. Thus, the aim of the study is to review the role of Nrf2 in cells exposed to most common mycotoxins to check if the Nrf2 signaling pathway serves as the main response element to mycotoxin-induced oxidative stress in human and animal cells and if it can be a target of detoxifying agents.

Effects of mycotoxin-contaminated feed on farm animals

Mycotoxins are secondary products produced by fungi in cereals and are frequently found in the livestock industry as contaminants of farm animal feed. Studies analyzing feed mycotoxins have been conducted worldwide and have confirmed the presence of mycotoxins with biological activity, including aflatoxin, ochratoxin A, fumonisin, zearalenone, and deoxynivalenol, in a large proportion of feed samples. Exposure to mycotoxins can cause immunotoxicity and impair reproductive function in farm animals. In addition, exposure of tissues, such as the kidneys, liver, and intestines, to mycotoxins can exert histopathological changes that can interfere with animal growth and survival. This review describes previous studies regarding the presence of major mycotoxins in the feed of farm animals, especially pigs and poultry. Moreover, it describes the adverse effects of mycotoxins in farm animals following exposure, as well as the biological activity of mycotoxins in animal-derived cells. Mycotoxins have been shown to regulate signaling pathways, oxidative stress, endoplasmic reticulum stress, apoptosis, and proliferation in porcine and bovine cells. A clear understanding of the effects of mycotoxins on farm animals will help reduce farm household economic loss and address the health concerns of people who consume these meat and dairy products.

Presence of unreported carcinogens, Aflatoxins and their hydroxylated metabolites, in industrialized Oaxaca cheese from Mexico City

Aflatoxins (AFs) are toxic secondary metabolites of the fungi Aspergillus flavus, A. parasiticus and A. nomius. The fungi produce these AFs in cereals, oilseeds and spices. AFs have damaging effects on all organisms, including humans, and their symptoms can be classified as acute (vomiting, hemorrhage and death) or chronic (immunodepression, Reye syndrome, Kwashiorkor, teratogenesis, hepatitis, cirrhosis, and various cancers). Basic AFs (AFB₁, AFB₂, AFG₁, and AFG₂) are metabolized in the liver or by microbes that produce hydroxylated metabolites (AFM₁, AFM₂, and AFP₁) and aflatoxicol (AFL), soluble in water and easy to dispose. Thus, AFs can be excreted in fluids, such as milk. AFs are not destroyed in the process of making cheese. The purpose of this study was to identify and quantify the AFs present in 30 samples of industrialized Oaxaca-type cheese sold in Mexico City. The average concentrations of AFs detected in the 30 samples of industrialized cheese were as follows: AFB₁ (0.1 μg kg^-1) in 20% (6/30); a trace amount of AFB₂ (0.01 < LOD) in only 3% (1/30); AFG₁ (0.14 μg kg^-1) in 10% (3/30); AFG₂ (0.6 μg kg^-1) in 30% (9/30); AFM₁ (1.7 μg kg^-1) in 57% (17/30); AFP₁ (0.03% μg kg^-1) in 3% (1/30); and AFL (13.1 μg kg^-1) in 97% (29/30). AFB₁ and AFL were the most abundant aflatoxins in Oaxaca-type cheese. However, eight aflatoxins were present, contributing an average of 15.7 μg kg^-1 AFs distributed among the 30 samples. The risk assessment analysis showed that there was no substantial risk for cancer due to AFs in industrialized Oaxaca cheese from Mexico City.

The effects of aflatoxin B1 on growth hormone regulated gene-1 and interaction between DNA and aflatoxin B1 in broiler chickens during hatching

Many types of aflatoxin cause problems for both public and animal health. Aflatoxin B₁ (AFB₁) is the most toxic and commonly encountered fungal toxin that appears in poultry feed and in feeds stored under unsuitable conditions. AFB₁ decreases feed quality, egg production and fertility of hatching eggs. Also, AFB₁ alters the development of embryos by infecting eggs. We investigated using sequence analysis the changes caused by different concentrations of AFB₁ on the promoter sequences of the growth hormone regulated gene-1 (GHRG-1) in chick embryo at 13, 17, 19 and 21 days incubation. DNA isolated from the liver of chick embryos treated with different concentrations of AFB₁ was separated using agarose gel electrophoresis to detect apoptosis, and DNA interaction with AFB₁ was investigated using plasmids to detect changes in electrophoretic mobility and their effects on DNA. Base changes of the promoter sequences of GHRG-1 in 5 ng/egg, 15 ng/egg and 40 ng/egg doses of AFB₁ were increased on day 19 compared to base changes of the same AFB₁ doses on day 13. We also found that AFB at different concentrations changed the mobility of DNA by binding to it, and that high doses of AFB1 destroyed DNA. The DNA interaction study using plasmid demonstrated that AFB₁ at high doses was bound to plasmid DNA, slowed its mobility and inhibited restriction cuts.

Aflatoxin B1 affects apoptosis and expression of Bax, Bcl-2, and Caspase-3 in thymus and bursa of fabricius in broiler chickens

Aflatoxin B1 is known as a mycotoxin that develops various health problems of animals, the effects of AFB1 on thymus and bursa of Fabricius in chickens are not clear. The objective of this study was to investigate the apoptosis of thymus and bursa of Fabricius in broilers fed with AFB1 . Two hundred Avian broilers were randomly divided into four groups of 50 each, namely control group and three AFB1 groups fed with 0.15 mg, 0.3 mg, and 0.6 mg AFB1 /kg diet, respectively. In this study, flow cytometer and immunohistochemical approaches were used to determine the percentage of apoptotic cells and the expression of Bax, Bcl-2, and Caspase-3. The results showed that consumption of AFB1 diets results in increased percentage of apoptotic cells and increased expression of Caspase-3 in both thymus and bursa of Fabricius. The expression of Bax was increased and the expression of Bcl-2 was decreased in the thymus, but no significant changes in Bax and Bcl-2 expression were observed in the bursa of Fabricius when broilers fed with AFB1 . These findings suggest that adverse effects of AFB1 on thymus and bursa of Fabricius in broilers were confirmed by increased apoptotic cells and abnormal expression of Caspase-3. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1113-1120, 2016.

The toxic effects of combined aflatoxins and zearalenone in naturally contaminated diets on laying performance, egg quality and mycotoxins residues in eggs of layers and the protective effect of Bacillus subtilis biodegradation product

The toxic effect of aflatoxins (AF) and zearalenone (ZEA) and their combination on laying performance, egg quality and toxins residues in eggs, as well as the efficacy of Bacillus subtilis biodegradation product (BDP) for ameliorating these effects in layers were evaluated. Layers were submitted to a two phase experiment. The first phase was an intoxication period (18-23 wk) with birds fed 7 (3 × 2 + 1) diets (3 treatments with mycotoxins: AF (123.0 μg/kg), ZEA (260.2 μg/kg), or AF + ZEA (123.0 + 260.2 μg/kg); 2 treatments with or without BDP (1000 g/t); and a control group contained no toxins nor BDP). The next phase was a recovery period (24-29 wk) in which birds were fed a toxin-free diet. In the intoxication period, AF and AF + ZEA groups exhibited lower egg production, feed intake and shell thickness, and higher AFB1, AFB2 and AFM1 residues as compared with the control group. In addition, AF and ZEA exerted synergistic effects on egg production and feed intake. Moreover, AF alone or combined with ZEA had a continuous toxic effect on laying performance in the recovery phase. Addition of BDP offset these negative effects, showing that BDP has a protective effect on layers fed contaminated diets.

Dietary vitamin E in White Leghorn layer breeder hens: a strategy to combat aflatoxin B1-induced damage

Mycotoxins are unavoidable contaminants of animal and human feed and food respectively. This study was designed to investigate the protective activity of vitamin E (Vit E) in White Leghorn breeder hens and their progeny against aflatoxin B1 (AFB1)-induced damage. The results indicated a significant decrease in egg production and quality in the groups exposed to dietary AFB1. A detectable amount of AFB1 residue appeared in the eggs during the first week of mycotoxin exposure at levels ≥ 2.5 mg kg(-1), which reached its peak (0.403 ± 0.04 ng/g [mean ± standard deviation]) during the second week of the experiment (in the group fed 10 mg kg(-1)). Feeding Vit E + AFB1 resulted in higher AFB1 residues (0.467 ± 0.03) when compared with the hens fed AFB1 alone. The resistance of red blood cells to oxidative damage was decreased, while embryonic mortalities and deformities were increased in the AFB1-fed groups. The protective effect of Vit E on these parameters was noted in the groups fed lower doses of AFB1. After the withdrawal of mycotoxin-contaminated feed, most of the parameters returned towards normal within 2 weeks, except AFB1 residues that were still detectable. From the findings of this study one can conclude that the addition of Vit E in the diet of hens provided only partial protection against AFB1-induced damage.

Effects of aflatoxin B1 on oxidative stress markers and apoptosis of spleens in broilers

The purpose of the present study was to investigate the oxidative damage and apoptosis induced by aflatoxin B1 (AFB1) in spleen of broilers. A total of 200 one-day-old avian male broilers were randomly divided into 4 equal groups of 50 each and were fed for 21 days as follows: a control diet and three AFB1 diets containing 0.15, 0.3, and 0.6 mg AFB1/kg diet. Consumption of AFB1 diets induced oxidative stress in the spleen of chicken as evidenced by reduced glutathione peroxidase, glutathione reductase, and catalase activities, decreased glutathione contents, and increased malondialdehyde contents in explaining the pathogenesis. Flow cytometer method and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay revealed that the apoptotic splenocytes were increased in AFB1 groups. The results suggest that AFB1 induced excessive apoptosis of splenic lymphocytes, which is correlated with increased oxidative stress. The present results may be helpful for explaining the pathogenesis of AFB1-induced immunosuppression.

Lipid metabolism of commercial layers fed diets containing aflatoxin, fumonisin, and a binder

Aflatoxins (AF) and fumonisins (FU) are a major problem faced by poultry farmers, leading to huge economic losses. This experiment was conducted to determine the effects of AF (1 mg/kg of feed) and FU (25 mg/kg of feed), singly or in combination, on the lipid metabolism in commercial layers and investigate the efficacy of a commercial binder (2 kg/t of feed) on reducing the toxic effects of these mycotoxins. A total of 168 Hisex Brown layer hens, 37 wk of age, were randomized into a 3 × 2 + 1 factorial arrangement (3 diets with no binder containing AF, FU, and AF+FU; 3 diets with binder containing AF, FU, and AF+FU; and a control diet with no mycotoxins and binders), totaling 7 treatments. The hens contaminated with AF showed the characteristic effects of aflatoxicosis, such as a yellow liver, resulting from the accumulation of liver fat, lower values of plasma very low-density lipoprotein and triglycerides, and higher relative weight of the kidneys and liver. Hepatotoxic and nephrotoxic effects of FU were not observed in this study. On the other hand, the FU caused a reduction in small intestine length and an increase in abdominal fat deposition. The glucan-based binder prevented some of the deleterious effects of these mycotoxins, particularly the effects of AF on hepatic lipid metabolism, kidney relative weight, and FU in the small intestine.

Role of Adhatoda vasica (L.) Nees leaf extract in the prevention of aflatoxin-induced toxicity in Wistar rats

BACKGROUND

Aflatoxin contamination of various foodstuffs and agricultural commodities is a major problem worldwide. Several strategies have been reported for the detoxification of aflatoxins in contaminated foods and feeds, but all these methods have their own shortcomings. Traditional medicinal plants are potential sources of aflatoxin-detoxifying compounds. In this study a spray-dried formulation of Adhatoda vasica (L.) Nees leaf extract was prepared and its chemopreventive effect on aflatoxin B1 (AFB1)-induced biochemical changes in the liver and serum of Wistar rats was investigated.

RESULTS

Administration of AFB1 (1.5 mg kg(-1) body weight (BW) intraperitoneally) to rats significantly reduced the activities of superoxide dismutase and catalase in liver tissues and increased the activities of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase and the levels of very-low-density lipoprotein, low-density lipoprotein and cholesterol in blood serum. However, pre-feeding of rats with A. vasica formulation (500 mg kg(-1) BW for 7 days) protected the animals from AFB1-induced biochemical changes during subsequent exposure to AFB1.

CONCLUSION

Pre-feeding of rats with A. vasica formulation counteracted the hepatic dysfunction induced by subsequent treatment with AFB1. This formulated A. vasica extract offers a biologically safe alternative to detoxify aflatoxin and has huge potential to be used in the poultry industry to reduce aflatoxicosis.

Effects of individual and combined administration of ochratoxin A and aflatoxin B1 in tissues and eggs of White Leghorn breeder hens

BACKGROUND

Mycotoxins, the secondary fungal metabolites, are unavoidable contaminants of human and animal food and feeds. The objectives of this study were to evaluate the effect of concurrent feeding of ochratoxin A (OTA) and aflatoxin B(1) (AFB(1) ) to breeder hens, upon their deposition in different tissues and eggs.

RESULTS

Residues of OTA and AFB(1) in (ng g(-1) ) were significantly higher in liver followed by kidneys and breast muscles by 22.54 ± 1.48, 4.22 ± 0.93 and 0.56 ± 0.06 for OTA (group fed OTA at 5 mg kg(-1) diet) and 1.44 ± 0.21, 0.25 ± 0.01 and 0.03 ± 0.01 for AFB(1) (group fed AFB(1) at 5 mg kg(-1) diet), respectively. Residues of OTA and AFB(1) in eggs appeared at days 3 and 5 of toxin feeding and disappeared at days 5 and 6 of withdrawal of mycotoxins contaminated feed, respectively. The residues of OTA and AFB(1) were significantly lower in the tissues of hens fed these toxins concurrently compared with the groups fed OTA and AFB(1) independently.

CONCLUSIONS

Residues of OTA and AFB(1) appeared in the tissues and eggs of laying hens kept on OTA- and AFB(1) -contaminated diets. Concurrent feeding of OTA and AFB(1) to hens significantly decreased the concentration of OTA and AFB(1) residues in the tissues and eggs.

Identification and quantification of aflatoxins and aflatoxicol from poultry feed and their recovery in poultry litter

Aflatoxins (AF) are toxic fungal secondary metabolites and are known mycotoxins pathological to animals and humans. Poultry litter is frequently used as a food supplement for ruminants, and when poultry feed contains AF, the litter becomes contaminated as well, thus having an effect on livestock health. This study identified and quantified AF (AFB(1), AFB(2), AFG(1), and AFG(2)) from poultry feed and their recovery, together with their metabolites (AFM(1), AFM(2), AFP(1), and aflatoxicol) in litter. An experiment with 25 Hy-Line W-36 hens, in their second production stage, 121 wk old, was carried out. Hens were distributed in 3 groups placed in individual cages and 1 ration of 250 g of feed was given to each hen daily. Nine hens of the control group were fed with clean feed, without AFB(1); the other 2 experimental groups, with 8 hens each, were fed with 2 AFB(1) concentrations: 30 and 500 microg.kg(-1). The feed was replaced and weighed daily throughout a 7-d period to register the amount of feed consumed by the hens. Litter from each hen was collected, weighed, and dried individually. The chemical analysis of 40 g of each one of the 200 feed and 200 litter samples was chemically extracted and concentrated with immunoaffinity columns for total AF. To quantify AF, calibration curves for each AF were done by HPLC. Feed samples of the 3 groups presented significant difference with AFB(2) and AFG(2), whereas in litter samples, there were significant differences for AFG(2) in the 500 microg.kg(-1) group. Poultry litter had traces of AFM(1), AFM(2), AFP(1), and AFL with no significant differences among treatments. Aflatoxin B(1) prevalence in litter samples can cause damages in livestock because this mycotoxin reduces the digestibility of ruminant feed up to 67%.

Aflatoxin contamination in food and body fluids in relation to malnutrition and cancer status in Cameroon

Aflatoxins are food contaminants usually associated with hepatitis, immunodepression, impairment of fertility and cancer. The present work was to determine the presence of aflatoxins in eggs, milk, urine, and blood samples that were collected from various sources and periods; and hepatitis B virus antigen in blood samples. Aflatoxin was found in eggs (45.2%), cow raw milk (15.9%), breast milk (4.8%), urine from kwashiorkor and marasmic kwashiorkor children (45.5%), and sera from primary liver cancer patients (63.9%); HbsAg was also detected in 69.4% of the serum samples, but there was no association between both factors. Both AF and hepatitis B virus seem to be risk factors that could increase the incidence and prevalence rates of malnutrition and cancer in Cameroon.

Microsomal and cytosolic biotransformation of aflatoxin B1 in four poultry species

1. This research evaluated differences in hepatic in vitro metabolism of aflatoxin B1 (AFB1) on selected avian species. 2. Microsomal and cytosolic liver fractions were obtained from chickens, ducks, quails and turkeys; eight males and eight females of each. 3. All microsomes studied produced AFB1-8,9-exo-epoxide (AFBO), a metabolite regarded as the active product of AFB1. Turkey microsomes produced 1.8 and 3.5 times more AFBO than quails and chickens microsomes, respectively. 4. Males from evaluated birds produced more AFBO than females, but statistically-significant differences between genders were observed only in ducks and turkeys. 5. The cytosolic fraction from all four species produced aflatoxicol (AFL). Turkey and duck hepatic cytosol produced more AFL than from quail and chickens. 6. It is known that turkeys are very sensitive to AFB1, quails are intermediate and chickens are particularly resistant; the differences in AFBO production shown in our study may help to explain the difference in vivo responses among turkeys, quail and chickens. 7. Moreover, AFL may be related to AFB1 toxicity; it was produced in larger amounts by hepatic cytosol from the more susceptible species. 8. Because AFBO production by microsomes in ducks was relatively low, it is possible that other toxicity mechanisms are involved in this highly susceptible species.

Effect of dietary calcium propionate on performance, hepatic enzyme activities and aflatoxin residues in broilers fed a diet containing low levels of aflatoxin B1

This study was undertaken to the study toxic effects of aflatoxins and reducing toxic effects of calcium propionate on performance, hepatic enzyme activities and aflatoxin residues in broilers. Two hundred and seventy 1-day-old hybrid Arbor Acor broiler chickens were fed conventional feed for 3 days. Broilers were then randomly divided into nine groups of 30 birds each. The nine dietary treatments consisted of (1) conventional feed as a negative control diet, (2) 0.25% calcium propionate, (3) 0.5% calcium propionate, (4) 50 ppb aflatoxin B1, (5) 50 ppb aflatoxin B1 plus 0.25% calcium propionate, (6) 50 ppb aflatoxin B1 plus 0.5% calcium propionate, (7) 100 ppb aflatoxin B1, (8) 100 ppb aflatoxin B1 plus 0.25% calcium propionate, (9) 100 ppb aflatoxin B1 plus 0.5% calcium propionate. Test diets were offered for 6 weeks continuously and the birds were sacrificed. Decreased body weight gain, feed consumption and feed conversion ratio were observed in aflatoxin treated groups whereas aflatoxin B1-calcium propionate supplemented diet groups increased, in comparison to the control group. Significant difference was observed after 4 weeks of feeding. Serum samples were tested for gamma glutamyl transferase (gamma-GGT), aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Gamma-GGT, AST and ALT were significantly increased in aflatoxin treated groups, in comparison among the dietary treated groups. Muscle and liver tissues were analyzed for aflatoxin residues. The residual levels of aflatoxin B1 and aflatoxin M1 were significantly higher in liver than in muscle. The levels in the liver and the muscle were highest in the aflatoxin B1-supplemented groups and lower in the aflatoxin B1-calcium propionate supplemented groups. Results of this study indicate that addition of calcium propionate to diets containing aflatoxin B1 appears to be effective in reducing toxicity. Aflatoxin contamination in broiler feed may cause economic losses by lowering body weight gain. Therefore, lower levels of aflatoxin B1 in the chicken feeds should be required if all acceptable risk is to be avoided. Additionally, the risk of aflatoxins in broiler as a food appears to remain very low, although the levels of aflatoxins in human foods should be kept as low as possible to reduce the incidence of hepatic cancer.

Mannanoligosaccharides and aflatoxin B1 in feed for laying hens: effects on egg quality, aflatoxins B1 and M1 residues in eggs, and aflatoxin B1 levels in liver

Ninety-six laying hens were allocated to 4 groups and fed diets (control diet (0-0), diet supplemented with 2.5 ppm aflatoxin B1 (0-AF); diet supplemented with 0.11% mannanoligosaccharide (MOS-0); diet supplemented with 0.11% MOS and 2.5 ppm aflatoxin B1 (MOS-AF) for 4 wk to evaluate the effect of aflatoxin B1 (AFB1), mannanoligosaccharide (MOS), or both on egg quality and the in vivo efficacy of MOS to interact with an oral administration of AFB1. After 2 and 3 wk, egg weight decreased (P < 0.05) in the group fed MOS-0 versus groups on 0-0 and 0-AF. Egg shell weight was lower (P < 0.05) in the group fed 0-AF. Aflatoxin influenced color parameters, which were probably related to interference of AFB1 with lipid metabolism and pigmentary substances deposition in yolk. MOS appeared to increase protein percentage in albumen. No AFB1 or aflatoxin M1 (AFM1; a polar metabolite of AFB1) residues were found in eggs of the experimental groups. Livers from groups 0-0 and MOS-0 always tested negative for AFB1 and AFM1. Differences (P < 0.01) were found between AFB1 hepatic levels of group 0-AF (mean +/- SD: 4.13 +/- 1.95 ppb) and group MOS-AF (mean +/- SD: 2.21 +/- 1.37 ppb). The data demonstrated the ability of MOS to adsorb and degrade AFB1, reducing gastrointestinal absorption of AFB1 and its levels in tissues.

Deoxynivalenol and zearalenone residues in eggs of laying hens fed with a naturally contaminated diet: effects on egg production and estimation of transmission rates from feed to eggs

The potential for the Fusarium mycotoxins 4-deoxynivalenol (DON) and zearalenone (ZON) to enter the human food chain through contaminated eggs was assessed using a controlled feed study. Four groups of laying hens (eight in each group) were fed a diet that included differing amounts of naturally contaminated wheat containing DON ( approximately 20 mg kg(-1)) and ZON (0.5 mg kg(-1)). Eggs were collected and pooled from each group on a daily basis. Pooled samples were analyzed by liquid chromatography with mass spectrometry detection (LC-MS/MS). The method allowed DON, other type B trichothecenes, ZON, and its metabolites to be determined in a single multi-residue analysis. The selectivity of the MS/MS procedure allowed cleanup to be minimized (for DON, cleanup by immunoaffinity column was used) or eliminated (for ZON). The limits of detection of 0.01 microg kg(-1) for DON and 0.1 microg kg(-1) for ZON in eggs were lower than previously published methods. None of the samples analyzed had detectable levels of ZON or its metabolites. Although maximum levels of DON contamination (10 mg kg(-1) feed) were relatively high, no adverse effects were observed on egg production. On the basis of the determined DON levels in the hen's diet and the determined levels of DON in the corresponding eggs, transmission rates of 15 000:1, 18 000:1, and 29 000:1 for treatment levels 5, 7.5, and 10 mg DON kg(-1) feed, respectively, were found. These results show that, although eggs could be a human exposure route for DON, the levels are insignificant compared to the other sources, although the presence of metabolites of DON was not studied.

Aflatoxin B1and its interconverting metabolite aflatoxicol in milk: the situation in Mexico

Between 1996 and 1998, 580 litres of milk in Mexico were surveyed for aflatoxin B(1) (AFB(1)) and its metabolite aflatoxicol (AFL), which are mutagenic and carcinogenic mycotoxins that interconvert AFB(1)-AFL-AFB(1). The seven most consumed brands from different regions of Mexico included pasteurized and ultrapasteurized milk with four different fat levels: whole fat (28-33 g l(-1)), half-skimmed (10-20 g l(-1)), light (1-4 g l(-1)) and with vegetable oil (33 g l(-1)). Aflatoxins in each sample were concentrated with total aflatoxin immunoaffinity columns and quantitated by high-performance liquid chromatography. A milk sample was considered contaminated if it contained >/=0.05 microg l(-1) AFL. Pasteurization and ultrapasteurization of milk did not control contamination with AFL, which was present in 13% of samples at >/=0.05 microg l(-1) and in 8% at >/=0.5 microg l(-1), with a range of AFL from 0 to 12.4 microg l(-1). AFB(1) was present mainly in traces (0-0.4 microg l(-1)). The safest milk in relation to AFL contamination was imported milk powder with vegetable oil. There was a significant correlation between contamination of milk with AFL and the autumn (p<0.0002); the fat content was not significant.

Aflatoxin residues in eggs of laying Japanese quail after long-term administration of rations containing low levels of aflatoxin B1

The aim was to evaluate the excretion of residues of aflatoxin B(1) (AFB(1)), aflatoxin M(1) (AFM(1)), aflatoxin B(2a) (AFB(2a)) and aflatoxicol (AFL) in eggs of laying Japanese quail fed rations with low levels of aflatoxin B(1) for 90 days. The quail were randomly assigned into four experimental groups and given prepared rations containing either 0 (controls), 25, 50 or 100 microg AFB(1) kg(-1) feed. Thirty-two eggs per treatment were collected on days 1-7, 10, 20, 30, 60 and 90 of the aflatoxin treatment period, and submitted to aflatoxin analysis by high-performance liquid chromatography. Average egg production and feed consumption were not affected ( p > 0.05) by AFB(1). Egg weight was significantly lower ( p<0.05) only for groups exposed to 100 microg AFB(1) kg(-1). Residues of aflatoxins were detected in eggs at levels that ranged from 0.01 to 0.08 microg kg(-1) (AFB(1)), 0.03-0.37 microg kg(-1) (AFM(1)), 0.01-1.03 microg kg(-1)(AFB(2a)) and 0.01-0.03 microg kg(-1) (AFL). Results indicate that the excretion of aflatoxin residues in quail eggs might occur at relatively low concentrations under conditions of long-term exposure of quail to low levels of AFB(1).

Residues of aflatoxins in the liver, muscle and eggs of domestic fowls

The residue of aflatoxins in the liver, muscle and eggs of laying ducks, hens and quails and in broiler chickens was examined by conducting 7-day feeding experiments with a diet containing 3 ppm Aflatoxin B1 (AFB1). Birds were sacrificed on the 8th or 11th day of AFB1 feeding. AFB1 and its metabolites in the tissues and eggs were determined by HPLC. The tissue levels of AFB1 and its metabolites were higher in quail than in the other birds. The levels of AFB1 and its metabolites, including acid-hydrolyzable metabolites, were more than 10-fold higher in the liver than in the muscle in all the species. The ratio of AFB1 in the feed to the residual level in the liver was 383 in quail, but was > or = 5769 in the other birds. The corresponding ratios in the egg yolk and albumen of AFB1 were 4615 and 3846, respectively, in chicken hens, and these values were higher than those in the other birds.

Aflatoxin B1 residues in eggs of laying hens fed a diet containing different levels of the mycotoxin

The present study was carried out to evaluate the excretion of aflatoxin B1 residues in eggs of young laying hens fed aflatoxin B1-contaminated rations for 8 weeks. To this end, 96 twenty-week-old hens were randomly distributed into four experimental groups (24 birds per group) and given rations containing either 0 (controls), 100 micrograms, 300 micrograms or 500 micrograms aflatoxin B1/kg feed. Egg aflatoxin B1 residues were determined by thin layer chromatography; two samples per treatment per week were used for analysis. Egg production and average egg weights were not affected (p < 0.05) in the groups receiving aflatoxin B1-contaminated rations. Residues of aflatoxin B1 were detected only in the eggs of hens given 500 micrograms/kg feed, at levels that ranged from 0.05 to 0.16 microgram/kg (average: 0.10 microgram/kg). The results indicate that the feed to eggs aflatoxin B1 transmission ratio was approximately 5000:1, emphasizing the importance of controlling aflatoxin levels in rations for laying hens.

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.

Dietary exposure of broiler breeders to aflatoxin results in immune dysfunction in progeny chicks

Broiler breeder hens were fed diets amended with 0 and 10 mg/kg (Trial 1) or 0, 0.2, 1, or 5 mg/kg (Trial 2) of aflatoxin (AF). Fertile eggs collected during 14 d of AF feeding were examined for AF residues. Various immunological endpoints were examined in chicks hatched from these eggs. Eggs collected at 7 d of AF feeding (Trial 1) had 0.15 to 0.48 ng/g of AFB1 and 0.22 to 0.51 ng/g of aflatoxicol, whereas eggs collected at 14 d of AF feeding had 0.05 to 0.60 ng of AFB1/g and 0.19 to 1.20 ng of aflatoxicol/g. In both trials, AF dietary exposure resulted in embryonic mortality and reduction in hatchability compared to controls. The AF progeny chicks in Trial 2 had total anti-SRBC antibodies similar to the controls during the primary antibody response. However, at 5 and 7 d after secondary SRBC injection, the antibody levels in the 1 and 5 mg/kg AF groups were lower than those of controls. Depression in anti-Brucella abortus antibodies occurred only in chicks from the 5 mg/kg AF group. Furthermore, phagocytosis of SRBC and reactive oxygen intermediate production by macrophages from AF progeny chicks were reduced as compared with the control chicks. The findings of this study imply that the progeny chicks from hens consuming a AF-amended diet may be increasingly susceptible to disease owing to suppression of humoral and cellular immunity.

Selective aflatoxin B1-induced sister chromatid exchanges and cytotoxicity in differentiating B and T lymphocytes in vivo

The purpose of this study was to assess the genotoxic and cytotoxic effects of the fungal metabolite aflatoxin B1 (AfB1) on the developing immune system of the chick embryo, a model in vivo system. Of particular interest was the assessment of AfB1-mediated selective toxicity toward developing B lymphocytes as compared to T lymphocytes. In vivo bromodeoxyuridine (BrdU) labelling of DNA was used to detect the induction of sister chromatid exchanges (SCE) in lymphocytes and to assess the progression of these cells through successive cell cycles. Cytotoxicity was also assessed by studying the entrance and maintenance of cells in mitosis (mitotic index). Graded doses of AfB1 (1.09-17.4 micrograms/g embryo) were applied to chick embryos at 18 days of incubation (DI). Embryos also received two doses of BrdU at 3 mg/200 microliters (3 hr apart) to provide continuous labelling of B and T lymphocyte replicating DNA. B and T lymphocytes were harvested 20 hr post-AfB1/BrdU exposure from the bursa and thymus, respectively, and were processed for cytogenetic analyses. AfB1 induced dose-related increases in SCE in B lymphocytes; this induction was 6- to 8-fold that of controls at the higher doses tested. AfB1-mediated induction of SCE in T cells was just 2-fold that of controls at the highest dose tested. AfB1 reduced the progression of B cells and to a lesser extent T cells through successive rounds of replication. Furthermore, AfB1 dramatically reduced the mitotic index of B cells but not of T cells. These data indicate both selective genotoxicity and cytotoxicity of AfB1 toward B cells in the late stage embryo.

Long-term administration of low doses of mycotoxins to poultry. 1. Residues of aflatoxin B1 and its metabolites in broilers and laying hens

A study was performed to determine aflatoxin residues in tissues and organs of male broilers and hens that had been fed a diet contaminated with 50 micrograms/kg aflatoxin B1 (AFB1). Residue levels of AFB1, aflatoxicol (Ro), aflatoxin M1 (AFM1) and aflatoxin B2a (AFB2a) were determined by an HPLC method and, with the exception of AFB2a, were detected in the liver, kidney and thigh of both male broilers and hens. The highest levels found were for Ro in liver (1.10 and 0.60 micrograms/kg for male broilers and hens, respectively). On the other hand no detectable amounts of aflatoxins were found in any tissue after withdrawal periods of 14 and 33 days for male broilers and laying hens respectively.

HPLC determination of the total content of aflatoxins in naturally contaminated eggs in free and conjugate forms

A study was undertaken to evaluate the total aflatoxin content in naturally contaminated eggs. Two pools of eggs from laying hens were collected after 2 and 7 days of treatment with aflatoxin B1 (AFB1). An HPLC method has been developed for the determination of AFB1, aflatoxin M1 (AFM1), aflatoxin B2a (AFB2a) and aflatoxicol (Ro) both in free form and after release from water-soluble conjugates. The bound form was cleaned up after acid hydrolysis of the aqueous phase. Eggs collected after 2 days of treatment revealed residues of AFB1, AFB2a and Ro in the organic phase, but none in the aqueous portion. After 7 days of treatment both AFB1 and its hydroxy derivative were found in the organic phase but the aqueous portion showed only hydroxylated metabolites accounting for 35% of the total aflatoxin content.

Aflatoxin carryover and clearance from tissues of laying hens

A feeding trial was conducted to determine the levels of aflatoxins deposited in the tissues of hens fed a diet contaminated with 3310 micrograms AFB1/kg and 1680 micrograms AFB2/kg for 4 wk. At the end of aflatoxin feeding, the livers were pale, enlarged and haemorrhagic and the ovaries were significantly smaller than those from control hens and contained only small ova. Only a small fraction of the aflatoxins consumed was deposited in the tissues, either as the original compounds or as their metabolites, which were widely distributed in all tissues. The highest levels of aflatoxins were detected in the gizzard, kidneys and liver, with average total concentrations of less than 3 micrograms/kg. The lowest residue levels were detected in the breast, blood serum and leg, with breast muscle having a total concentration of less than 0.1 microgram/kg. Two days after removal of the contaminated feed, aflatoxin residues in all tissues had decreased markedly, with no aflatoxins being detected in the heart or spleen. No aflatoxin residues were detected in the breast, leg, gizzard and ovaries of hens killed 8 days after withdrawal, or in the kidneys and blood at 16 days. However, one of seven hens had measurable amounts of AFB2 in the liver 32 days after withdrawal. Although few residues were detected in most tissues after 8 days on the aflatoxin-free diet, variation existed between tissues and between individual hens in the amount of time required to achieve tissue clearance.

Aflatoxin deposition and clearance in the eggs of laying hens

Hens fed a diet containing 3310 micrograms of AFB1 and 1680 micrograms of AFB2 per kg feed for 28 days showed a significant decrease in egg production and egg weights by wk 3 and 4 of feeding, respectively. Transfer of aflatoxins to the eggs occurred rapidly, reaching maximum levels after 4-5 days, and remained relatively constant throughout aflatoxin feeding. The mean values for combined residue levels in eggs were less than 0.5 microgram/kg. Levels of AFB2, AFM1 and AFM2 were similar in yolk and albumen while levels of B1 and B2a were higher in the yolk. Upon removal of the aflatoxin-containing diet, residues in eggs decreased rapidly. Clearance of aflatoxin residues from the albumen occurred faster than from the yolk. Thus, no residues were detected in the albumen and in the yolk after 5 and 7 days of withdrawal, respectively. No aflatoxin residues could be recovered from whole eggs after feeding the aflatoxin-free diet for 4 days.