The Efficacy of a Smectite-Based Mycotoxin Binder in Reducing Aflatoxin B1 Toxicity on Performance, Health and Histopathology of Broiler Chickens

The aim of the experiment was to investigate the efficacy of a smectite-based clay binder (Toxo-MX) in reducing the toxicological effects of aflatoxin B₁ (AFB₁) in commercial broiler chickens. A total of 450 one-day old male broiler chickens were randomly allocated into three treatment groups with ten replicates of 15 birds each in a 42-day feeding experiment. The dietary treatments included a negative control (NC, a basal diet with no AFB₁ and binder), a positive control (PC, a basal diet contaminated with 500 ppb of AFB₁) and a smectite-based mycotoxin binder(Toxo-MX, PC with smectite clay binder). AFB₁ challenge resulted in 14 to 24% depression in growth performance, elevated levels of aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT), organ enlargement and immuno-suppression.As compared to PC, feeding of Toxo-MX improved the final weight (15%; p < 0.0001), average daily gain (ADG) (15%; p < 0.001) and feed efficiency of broilers (13%; p < 0.0003) but did not have any effects on liver enzyme activities. Supplementation of smectite claysignificantly increased serum globulin levels and reduced the weight of the liver (p < 0.05) as compared to AFB₁-fed broiler chickens. The severity of lesions (inflammatory and degenerative changes) observed in the liver, kidney, heart, pancreas, and lymphoid organs in PC birds was reduced by feeding smectite clay. The immuno-suppression caused by AFB₁ was moderately ameliorated in Toxo-MX groupby stimulating the production of antibodies against IBD at day 42 (p < 0.05). In conclusion, dietary supplementation of a smectite-based mycotoxin binder to the diet containing AFB₁ improved growth performance, reduced toxicological effects in liver and improved humoral immune response in broilers, suggesting its protective effect against aflatoxicosis.

Occurrence of Zearalenone and Its Metabolites in the Blood of High-Yielding Dairy Cows at Selected Collection Sites in Various Disease States

Zearalenone (ZEN) and its metabolites, alpha-zearalenol (α-ZEL) and beta-zearalenol (β-ZEL), are ubiquitous in plant materials used as feed components in dairy cattle diets. The aim of this study was to confirm the occurrence of ZEN and its selected metabolites in blood samples collected from different sites in the hepatic portal system (posthepatic-external jugular vein EJV; prehepatic-abdominal subcutaneous vein ASV and median caudal vein MCV) of dairy cows diagnosed with mastitis, ovarian cysts and pyometra. The presence of mycotoxins in the blood plasma was determined with the use of combined separation methods involving immunoaffinity columns, a liquid chromatography system and a mass spectrometry system. The parent compound was detected in all samples collected from diseased cows, whereas α-ZEL and β-ZEL were not identified in any samples, or their concentrations were below the limit of detection (LOD). Zearalenone levels were highest in cows with pyometra, where the percentage share of average ZEN concentrations reached 44%. Blood sampling sites were arranged in the following ascending order based on ZEN concentrations: EJV (10.53 pg/mL, 44.07% of the samples collected from this site), ASV (14.20 pg/mL, 49.59% of the samples) and MCV (26.67 pg/mL, 67.35% of the samples). The results of the study indicate that blood samples for toxicological analyses should be collected from the MCV (prehepatic vessel) of clinically healthy cows and/or cows with subclinical ZEN mycotoxicosis. This sampling site increases the probability of correct diagnosis of subclinical ZEN mycotoxicosis.

Toxic Effect of Aflatoxins in Dogs Fed Contaminated Commercial Dry Feed: A Review

Since its first patent (1897), commercial dry feed (CDF) for dogs has diversified its formulation to meet the nutritional needs of different breeds, age, or special conditions and establish a foundation for integration of these pets into urban lifestyles. The risk of aflatoxicosis in dogs has increased because the ingredients used to formulate CDF have also proliferated, making it difficult to ensure the quality required of each to achieve the safety of the entire CDF. This review contains a description of the fungi and aflatoxins detected in CDF and the ingredients commonly used for their formulation. The mechanisms of action and pathogenic effects of aflatoxins are outlined; as well as the clinical findings, and macroscopic and microscopic lesions found in aflatoxicosis in dogs. In addition, alternatives for diagnosis, treatment, and control of aflatoxins (AF) in CDF are analyzed, such as biomarkers of effect, improvement of blood coagulation, rate of elimination of AF, control of secondary infection, protection of gastric mucosa, reduction of oxidative stress, use of chemo-protectors, sequestrants, grain-free CDF, biocontrol, and maximum permitted limits, are also included.

Development of a genetic evaluation for hair shedding in American Angus cattle to improve thermotolerance

BACKGROUND

Heat stress and fescue toxicosis caused by ingesting tall fescue infected with the endophytic fungus Epichloë coenophiala represent two of the most prevalent stressors to beef cattle in the United States and cost the beef industry millions of dollars each year. The rate at which a beef cow sheds her winter coat early in the summer is an indicator of adaptation to heat and an economically relevant trait in temperate or subtropical parts of the world. Furthermore, research suggests that early-summer hair shedding may reflect tolerance to fescue toxicosis, since vasoconstriction induced by fescue toxicosis limits the ability of an animal to shed its winter coat. Both heat stress and fescue toxicosis reduce profitability partly via indirect maternal effects on calf weaning weight. Here, we developed parameters for routine genetic evaluation of hair shedding score in American Angus cattle, and identified genomic loci associated with variation in hair shedding score via genome-wide association analysis (GWAA).

RESULTS

Hair shedding score was moderately heritable (h2 = 0.34 to 0.40), with different repeatability estimates between cattle grazing versus not grazing endophyte-infected tall fescue. Our results suggest modestly negative genetic and phenotypic correlations between a dam's hair shedding score (lower score is earlier shedding) and the weaning weight of her calf, which is one metric of performance. Together, these results indicate that economic gains can be made by using hair shedding score breeding values to select for heat-tolerant cattle. GWAA identified 176 variants significant at FDR < 0.05. Functional enrichment analyses using genes that were located within 50 kb of these variants identified pathways involved in keratin formation, prolactin signalling, host-virus interaction, and other biological processes.

CONCLUSIONS

This work contributes to a continuing trend in the development of genetic evaluations for environmental adaptation. Our results will aid beef cattle producers in selecting more sustainable and climate-adapted cattle, as well as enable the development of similar routine genetic evaluations in other breeds.

Toxic tall fescue grazing increases susceptibility of the Angus steer fecal microbiota and plasma/urine metabolome to environmental effects

Impaired thermoregulation and lowered average daily gains (ADG) result when livestock graze toxic endophyte (Epichloë coenophialum)-infected tall fescue (E+) and are hallmark signs of fescue toxicosis (FT), a disease exacerbated by increased temperature and humidity (+temperature-humidity index; +THI). We previously reported FT is associated with metabolic and microbiota perturbations under thermoneutral conditions; here, we assessed the influence of E+ grazing and +THI on the microbiota:metabolome interactions. Using high-resolution metabolomics and 16S rRNA gene sequencing, plasma/urine metabolomes and the fecal microbiota of Angus steers grazing non-toxic or E+ tall fescue were evaluated in the context of +THI. E+ grazing affected the fecal microbiota profile; +THI conditions modulated the microbiota only in E+ steers. E+ also perturbed many metabolic pathways, namely amino acid and inflammation-related metabolism; +THI affected these pathways only in E+ steers. Integrative analyses revealed the E+ microbiota correlated and co-varied with the metabolomes in a THI-dependent manner. Operational taxonomic units in the families Peptococcaceae, Clostridiaceae, and Ruminococcaceae correlated with production parameters (e.g., ADG) and with multiple plasma/urine metabolic features, providing putative FT biomarkers and/or targets for the development of FT therapeutics. Overall, this study suggests that E+ grazing increases Angus steer susceptibility to +THI, and offers possible targets for FT interventions.

Toxicopathological effects of feeding aflatoxins B1 in broilers and its ameliosration with indigenous mycotoxin binder

Mycotoxicosis is the second most important problem faced by the Pakistan poultry industry, after high feed prices. The present experimental study was designed to investigate the toxicopathological effects of aflatoxin B1 (AFB1) in commercial broiler chicks and its amelioration with locally produced mycotoxin binder. Total of 125 broiler chicks was divided into five equal groups (A-E). Group A served as negative control, group B (300 μg AFB1/kg feed) as positive control, group C (300 μg AFB1/kg + Local Mycotoxin Binder (LMB), 1 g/kg feed), group D (300 μg AFB1/kg + 2 g LMB/kg feed), and group E (300 μg AFB1/kg + Commercial Mycotoxin Binder (CMB), 2 g/kg of feed). Parameters studied included mortality, feed intake, bodyweights, absolute and relative organ weights, and gross and microscopic lesions in visceral organs. Clinical signs including alertness, fecal consistency, and feather shine were significantly lower in group B compared with control group A. The feed intake of 2 g/kg LMB treated group was significantly higher than that of the positive control group B. Also mean bodyweights of group D birds was higher than that of group B birds indicating an ameliorative effect of LMB. Histopathological results showed that moldy feed produced necrotic changes in the liver and kidneys in group B birds. However, in group D and E birds, the hepatic and renal parenchyma was normal, showing a protective effect of LMB. In the present study, a higher dose of LMB (2 g/kg) in group D showed higher bodyweights and feed intake. In group D, birds hepatic and renal parenchyma was also normal. The results suggested that local mycotoxin binder ameliorated the toxicopathological effects of AFB1 in mortality, feed intake, bodyweights, organ weights and, gross and microscopic lesions in visceral organs. These ameliorative effects of LMB were dose-dependent. The results of the present study concluded that AFB1 intoxication leads to decrease in bodyweights, feed intake in dose-related manner. The mortality was also dose-dependent. Gross and microscopic changes in the aflatoxin groups were more pronounced, however, all these deleterious effects were ameliorated in higher dose of LMB (group D) and CMB (group E). In group C, these deleterious effects were partially ameliorated. Local mycotoxin binder is an economical solution for aflatoxicosis problem, making poultry production more cost-effective.

Nutrient stability in mould-infested feed and mitigating effect of dietary supplemental vitamins in brown laying hens

A 10-week study was conducted to assess the impact of mould infestation on nutrient stability of feed and the mitigating effect of supplemental tocopherol, retinol or a multivitamin on performance and hepatic histology of ISA Brown laying chickens. Two batches of corn were obtained: the aflasafe corn used in preparing control diet and corn with physical evidence of mould used in preparing diets 2 to 5 containing no supplemental vitamin, tocopherol, retinol or a branded multivitamin supplementations respectively. One hundred and fifty (150) laying chickens used were completely randomized into five dietary treatments with three replicates of 10 birds each. Results showed that there was gross instability in the nutrients of mouldy maize. The activities of the fungi depleted both protein and lipid contents by 11.54% and 12.72% respectively while crude fibre content rose by 31.7%. There was substantial drop in both retinol and tocopherol while aflatoxin content rose to 267 μg in mouldy corn and 118 μg in the mouldy diets. Feed intake was significantly (P < 0.05) reduced and consequently depressed (P < 0.05) egg production and feed efficiency. Egg quality differs (P < 0.05) in shell thickness and yolk colour. Proliferation of biliary duct epithelium, hepatic degeneration, cellular infiltration, hyper-cellularity or dilation of the sinusoidal spaces characterized livers of birds on mouldy corn diets while supplementation with vitamins subverted mycosis and aflatoxicosis as evidenced by normal-to-mild congestion of hepatocytes. It was concluded that mould contamination in feed compromised feed nutritive values, reduced bird performance and adversely impaired the liver of the experimental birds while tocopherol, retinol or a multivitamin supplementation relapses the damaging potential of mould and mycotoxin differently.

Comparative evaluation of aflatoxin and mineral binding activity of molecular imprinted polymer designed for dummy template using in vitro and in vivo models

The amelioration of aflatoxicosis in ducklings was examined by feeding molecular imprinted polymer (MIP) synthesized to target the aflatoxin B₁ (AFB₁) analog molecule [5, 7-dimethoxycoumarin (DMC)] as a smart and novel toxin binder in comparison to a commercial toxin binder (CTB). MIP was characterized with some techniques, such as scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) that showed morphology and thermal resistance of MIP, respectively. The SEM showed that more pores and big cavities were formed in the network of the MIP. TGA plots of MIP showed dehydration at temperatures of about 31 °C-200 °C and gradual decomposition until 300 °C. The in vitro and in vivo ability of MIP and CTB to adsorb some minerals (Ca, Cu, Mg, P and Zn) was evaluated. The in vivo efficacy of MIP as an aflatoxins (AFs) binder in duckling exposed to aflatoxin-contaminated feed from 4 to 18 d of age was also compared to that of the CTB. A total of 240 4-d-old ducklings were assigned to experimental diets. Each diet was replicated four times with 10 birds in each pen, and the initial body weight classes were considered as blocks. The experimental treatment diets included: 1- Control (basal diet without any additive or AFs), 2- MIP (5 g/kg diet), 3- CTB (5 g/kg diet), 4- AFs (0.2 mg/kg diet), 5- AFs + MIP (0.2 mg/kg + 5 g/kg diet), and 6- AFs + CTB (0.2 mg/kg + 5 g/kg diet). In vitro study may clearly reflect the possibility of adsorbing minerals by CTB as compared to MIP whilst the results were not confirmed by in vivo study and it seems that reduction in plasma levels of minerals is related to the adverse effects of AFs. Livers showed histopathological alterations, with bile-duct proliferation of all aflatoxin fed ducklings. Macroscopic study indicated liver of birds fed diets containing AFs showed abnormal signs including yellowish, friable and rounded shape without protective effect of MIP and CTB. The results obtained from in vivo study indicate the partial alleviation of the adverse effects of AFs in ducklings by dietary supplementation of MIP and CTB (5 g/kg) on plasma albumin, Zn, Mg and Ca.

Effects of High Levels of Deoxynivalenol and Zearalenone on Growth Performance, and Hematological and Immunological Parameters in Pigs

Background: Deoxynivalenol (DON) and zearalenone (ZEN) are common food contaminants produced by Fusarium sp. Mycotoxins are a potential health hazard because of their toxicological effects on both humans and farmed animals. Methods: We analyzed three groups of pigs: a control group (fed a standard diet), and the DON and ZEN groups, fed a diet containing 8 mg/kg DON and 0.8 mg/kg ZEN respectively, for four weeks. Results: DON and ZEN exposure decreased body weight (BW), average daily feed intake (ADFI), food conversion rate (FCR), and the serum levels of immunoglobulin (Ig)G and IgM. The total antioxidant levels significantly decreased in serum and increased in urine samples of both treatment groups. Additionally, DON and ZEN exposure increased serotonin levels in urine. Hematological parameters were not affected by the investigated toxins. Microscopic lesions were evident in sections of kidneys from either treatment group: we found sporadic interstitial nephritis in the DON group and renal glomerulus atrophy in the ZEN group. The expression levels of inflammatory cytokines and chemokine marker genes were reduced in tissues from DON- and ZEN-exposed pigs. Conclusions: chronic ingestion of high doses of DON and ZEN alters the immune response and causes organs damage, and might be associated with various diseases in pigs.

Prevalence of Degnala disease in bovine along with screening of toxigenic fungi isolated from contaminated rice straw

Toxigenic potential of different candidate fungi, isolated from rice straw feed of Degnala disease affected bovines was analyzed along with species, age, gender and seasonal prevalence. Of 1,536 cases, 104 (6.77%) showed positive signs with a significant association (p less than 0.05) between this disease and rice straw feeding, in buffaloes, and bovine aged over 1 year in the winter season. Complete blood count showed a marked increase in erythrocyte sedimentation rate and all white blood cells numbers, except lymphocytes in positive cases. There was a significant increase (p less than 0.05) in alanine amino transferase, aspirate amino transferase and alkaline phosphatase in the liver function test. At the same time, an increased value of creatinine was noted in the renal function test. For isolation and screening of toxigenic fungi, rice straw samples (n=40) being fed to the positive cases were processed further, and 85 fungal isolates were found, mainly of Aspergillus (57), Penicillium (10), Fusarium (04), Zygomycetes (03), Curvularia (01) and unidentified (10). All isolated fungi were subjected for mycotoxin production and only 11 showed mycotoxin-producing capability (including Aspergillus, Penicillium and Fusarium isolates) analyzed by thin layer chromatography and quantified through high performance liquid chromatography. It is concluded that all the fungi contaminating rice straw feed of Degnala affected animals were not toxigenic. This work will help in establishing major mycotoxin-producing fungi leading to the probable cause of Degnala disease in bovine.

Brevetoxin exposure in sea turtles in south Texas (USA) during Karenia brevis red tide

Five green (Chelonia mydas) and 11 Kemp's ridley (Lepidochelys kempii) sea turtles found dead, or that died soon after stranding, on the southern Texas (USA) coast during 2 Karenia brevis blooms (October 2015, September-October 2016) were tested for exposure to brevetoxins (PbTx). Tissues (liver, kidney) and digesta (stomach and intestinal contents) were analyzed by ELISA. Three green turtles found alive during the 2015 event and 2 Kemp's ridley turtles found alive during the 2016 event exhibited signs of PbTx exposure, including lethargy and/or convulsions of the head and neck. PbTx were detected in 1 or more tissues or digesta in all 16 stranded turtles. Detected PbTx concentrations ranged from 2 to >2000 ng g-1. Necropsy examination and results of PbTx analysis indicated that 10 of the Kemp's ridleys and 2 of the green turtles died from brevetoxicosis via ingestion. This is the first documentation of sea turtle mortality in Texas attributed to brevetoxicosis.

Ameliorative Effects of Neutral Electrolyzed Water on Growth Performance, Biochemical Constituents, and Histopathological Changes in Turkey Poults during Aflatoxicosis

Different in vitro and in silico approaches from our research group have demonstrated that neutral electrolyzed water (NEW) can be used to detoxify aflatoxins. The objective of this investigation was to evaluate the ability of NEW to detoxify B-aflatoxins (AFB₁ and AFB₂) in contaminated maize and to confirm detoxification in an in vivo experimental model. Batches of aflatoxin-contaminated maize were detoxified with NEW and mixed in commercial feed. A total of 240 6-day-old female large white Nicholas-700 turkey poults were randomly divided into four treatments of six replicates each (10 turkeys per replicate), which were fed ad libitum for two weeks with the following dietary treatments: (1) control feed containing aflatoxin-free maize (CONTROL); (2) feed containing the aflatoxin-contaminated maize (AF); (3) feed containing the aflatoxin-contaminated maize detoxified with NEW (AF + NEW); and (4) control feed containing aflatoxin-free maize treated with NEW (NEW). Compared to the control groups, turkey poults of the AF group significantly reduced body weight gain and increased feed conversion ratio and mortality rate; whereas turkey poults of the AF + NEW group did not present significant differences on productive parameters. In addition, alterations in serum biochemical constituents, enzyme activities, relative organ weight, gross morphological changes and histopathological studies were significantly mitigated by the aflatoxin-detoxification procedure. From these results, it is concluded that the treatment of aflatoxin-contaminated maize with NEW provided reasonable protection against the effects caused by aflatoxins in young turkey poults.

Prevalence and effects of mycotoxins on poultry health and performance, and recent development in mycotoxin counteracting strategies

Extensive research over the last couple of decades has made it obvious that mycotoxins are commonly prevalent in majority of feed ingredients. A worldwide mycotoxin survey in 2013 revealed 81% of around 3,000 grain and feed samples analyzed had at least 1 mycotoxin, which was higher than the 10-year average (from 2004 to 2013) of 76% in a total of 25,944 samples. The considerable increase in the number of positive samples in 2013 may be due to the improvements in detection methods and their sensitivity. The recently developed liquid chromatography coupled to (tandem) mass spectrometry allows the inclusion of a high number of analytes and is the most selective, sensitive, and accurate of all the mycotoxin analytical methods. Mycotoxins can affect the animals either individually or additively in the presence of more than 1 mycotoxin, and may affect various organs such as gastrointestinal tract, liver, and immune system, essentially resulting in reduced productivity of the birds and mortality in extreme cases. While the use of mycotoxin binding agents has been a commonly used counteracting strategy, considering the great diversity in the chemical structures of mycotoxins, it is very obvious that there is no single method that can be used to deactivate mycotoxins in feed. Therefore, different strategies have to be combined in order to specifically target individual mycotoxins without impacting the quality of feed. Enzymatic or microbial detoxification, referred to as "biotransformation" or "biodetoxification," utilizes microorganisms or purified enzymes thereof to catabolize the entire mycotoxin or transform or cleave it to less or non-toxic compounds. However, the awareness on the prevalence of mycotoxins, available modern techniques to analyze them, the effects of mycotoxicoses, and the recent developments in the ways to safely eliminate the mycotoxins from the feed are very minimal among the producers. This symposium review paper comprehensively discusses the above mentioned aspects.

Regional differences in the fescue toxicosis response of Bos taurus cattle

Cattle of the same breed from different regions of the USA may have altered responses to heat stress and fescue toxicosis. Angus steers from Missouri (MO ANG, n = 10, 513.6 ± 13.6 kg BW) and Oklahoma (OK ANG, n = 10, 552.8 ± 12.0 kg BW) were fed a diet containing either endophyte-infected (E+, 30 μg ergovaline/kg BW/day) or endophyte-uninfected (E-, 0 μg ergovaline/kg BW/day) tall fescue seed for 23 days. Diet treatment began on day 2. Animals were maintained at thermoneutrality (TN, 19-22 °C, days 1-8) and then exposed to heat stress (HS, cycling 26-36 °C, days 9-22). On day 23, ambient temperature was returned to TN and used as a recovery day. Feed intake (FI) was measured daily, with rectal and skin temperatures determined six times daily. Feed intake reduction from pretreatment levels was greater (P < 0.01) for E + (13.9 ± 0.9 versus 11.9 ± 0.3 kg/day) compared to E - (12.6 ± 0.9 versus 12.4 ± 0.3 kg/day) steers over the entire TN period, regardless of Angus group. During HS, E + cattle had reduced FI (P < 0.02; 6.9 ± 0.2 versus 8.4 ± 0.2 kg/day) compared to E - animals, independent of region of origin. A greater decrease in FI (P < 0.01) was observed for OK (12.1 ± 0.3 versus 6.2 ± 0.2 kg/day) compared to MO ANG (12.2 ± 0.3 versus 7.9 ± 0.2 kg/day) when ambient temperature was increased from TN to HS. On day 13 and days 15-22, OK ANG (E+) had reduced FI (P < 0.01, -2.21 kg) compared to OK ANG (E-), while there was no effect on MO ANG. From day 12 to day 22 of HS, daily minimum temperatures for ear, rump, and tail skin were less for E + (P < 0.05) when compared with E-treated steers, signifying peripheral vasoconstriction in E + animals. This was supported by reduced shoulder and lower tail temperatures (P < 0.01) for E + compared to E-treated OK ANG on the recovery day. In summary, regional differences in the response to fescue toxicosis exist, with peripheral vasomotor effects becoming most evident when animals are subjected to rapid changes in their environment.

Optic neuropathy in a herd of beef cattle in Alberta associated with consumption of moldy corn

A group of beef cattle in eastern Alberta was investigated due to sudden onset of blindness after grazing on standing corn in mid-winter. Fumonisin-producing Fusarium spp. were isolated from the corn. Blindness was due to an optic nerve degeneration suspected to be secondary to fumonisin mycotoxin.

Dietary glutamate supplementation ameliorates mycotoxin-induced abnormalities in the intestinal structure and expression of amino acid transporters in young pigs

The purpose of this study was to investigate the hypothesis that dietary supplementation with glutamic acid has beneficial effects on growth performance, antioxidant system, intestinal morphology, serum amino acid profile and the gene expression of intestinal amino acid transporters in growing swine fed mold-contaminated feed. Fifteen pigs (Landrace×Large White) with a mean body weight (BW) of 55 kg were randomly divided into control group (basal feed), mycotoxin group (contaminated feed) and glutamate group (2% glutamate+contaminated feed). Compared with control group, mold-contaminated feed decreased average daily gain (ADG) and increased feed conversion rate (FCR). Meanwhile, fed mold-contaminated feed impaired anti-oxidative system and intestinal morphology, as well as modified the serum amino acid profile in growing pigs. However, supplementation with glutamate exhibited potential positive effects on growth performance of pigs fed mold-contaminated feed, ameliorated the imbalance antioxidant system and abnormalities of intestinal structure caused by mycotoxins. In addition, dietary glutamate supplementation to some extent restored changed serum amino acid profile caused by mold-contaminated feed. In conclusion, glutamic acid may be act as a nutritional regulating factor to ameliorate the adverse effects induced by mycotoxins.

RNA-Seq analysis implicates detoxification pathways in ovine mycotoxin resistance

Mycotoxin induced hepatoxocity has been linked to oxidative stress, resulting from either an increase in levels of reactive oxygen species (ROS) above normal levels and/or the suppression of antioxidant protective pathways. However, few detailed molecular studies of mycotoxicoses in animals have been carried out. This study use current RNA-seq based approaches to investigate the effects of mycotoxin exposure in a ruminant model. Having first assembled a de novo reference transcriptome, we use RNA-Seq technology to define in vivo hepatic gene expression changes resulting from mycotoxin exposure in relationship to pathological effect. As expected, characteristic oxidative stress related gene expression is markedly different in animals exhibiting poorer outcomes. However, expression of multiple genes critical for detoxification, particularly members of the cytochrome P450 gene family, was significantly higher in animals exhibiting mycotoxin tolerance ('resistance'). Further, we present novel evidence for the amplification of Wnt signalling pathway activity in 'resistant' animals, resulting from the marked suppression of multiple key Wnt inhibitor genes. Notably, 'resistance' may be determined primarily by the ability of an individual to detoxify secondary metabolites generated by the metabolism of mycotoxins and the potentiation of Wnt signalling may be pivotal to achieving a favourable outcome upon challenge.

Tremorgenic mycotoxicosis in dogs

Ingestion of tremorgenic mycotoxins formed in spoiled food can cause an acute tremor syndrome, the severity of which can range from mild to life-threatening. Swift recognition of the likely cause is required for accurate prognostication and rapid institution of appropriate therapy, which leads to complete resolution in most cases.

The effect of experimental low zearalenone intoxication on ovarian follicles in pre-pubertal bitches

Companion animals, including bitches, may be exposed to zearalenone (ZEN) toxins that are often present in feed, and ZEN intoxication may lead to ovarian dysfunction. This study involved evaluation of the degree of ZEN-induced hypo stimulation of ovary by determination of proliferative and apoptotic indices and description of the ultra-structural organization of ovarian follicles in pre-pubertal bitches subjected to experimental, long-term exposure to low-dose ZEN mycotoxicosis. The experiment involved 30 clinically healthy, immature Beagle bitches aged approximately 70 days with initial average body weight of 8 kg, randomly divided into three groups of 10 animals each: two experimental groups (EI and EII) and a control group (C). Over a period of 42 days, ZEN was administered per os to EI animals at a dose of 50 microg/kg BW, and to EII bitches at a dose of 75 microg/kg BW. Control group animals were fed placebo containing no ZEN for 42 days. Analytical samples of the mycotoxin were administered daily in gelatin capsules before morning feeding. All the bitches were subjected to ovario-hysterectomy at the end of the experiment. Proliferation index (PCNA method) and apoptotic index (TUNEL test) values were determined by immune-histological analyses. The median for apoptotic index was determined at 13.45 for group EI, 17.84 for group EII, and 8.59 for group C. The median for proliferation index was determined at 35.25 for group EII, 42.44 for group EI, and 70.60 for group C. The results of ultra-structural examinations of the ovaries revealed that experimental, ZEN-induced hyperestrogenism enhanced apoptosis and lowered the proliferative ability of follicular cells what contributed to organelle destruction in pre-pubertal bitches. The changes observed were particularly advanced in EII animals, which were administered a higher dose of ZEN.

The effect of low-dose experimental zearalenone intoxication on the immunoexpression of estrogen receptors in the ovaries of pre-pubertal bitches

Zearalenone is an estrogenic mycotoxin that often contaminates plant material used in the production of feeds for companion animals. Small daily doses of ingested zearalenone--a competitive substrate modulating the activity of enzymes participating in estrogen biosynthesis at the pre-receptor level--can induce subclinical symptoms of hyperestrogenism in bitches. The objective of this study was to determine the effects of low zearalenone doses on the presence of estrogen receptors in the ovaries of pre-pubertal Beagle bitches. The bitches were divided into three groups of 10 animals each: experimental group I--50 microg zearalenone/kg body weight administered once daily per os; experimental group II--75 microg zearalenone/kg body weight administered once daily per os; control group--placebo containing no ZEN administered per os. The animals were ovariorectomized at the end of the experiment, at 112 days of age. Estrogen receptors were detected in ovarian specimens by immunohistochemical methods. The results revealed an absence of estrogen receptors alpha in all groups. In both experimental groups a decrease in the positive response of estrogen receptors beta in specified structures of ovaries was observed. Very low alpha-zearalenol levels probably attested to the slowing down (hypostimulation) of the biotransformation process. Overall, zearalenone intoxication led to hyperestrogenism during a specific developmental stage of pre-pubertal bitches. As regards hormesis, the threshold dose of zearalenone (adaptive capability) was exceeded in the ovaries of experimental group II animals. The results obtained in both experimental groups suggest that long-term exposure to low-dose zearalenone intoxication decreased the degree of estrogen receptors beta staining in particular structures of ovaries in the experimental bitches, which initiated epigenetic modification mechanisms that inhibited ovarian development.

Effects in food-producing animals

Unexplained disease outbreaks in farm and domestic animals have suggested the likely presence of mycotoxins in feeds for many years. The manifestations of mycotoxicoses in the field are frequently nondescript and potentially have many contributing factors, which are often difficult to define. Nevertheless, toxigenic moulds were implicated in, and sometimes proven to be the cause of, animal disease in field outbreaks long before the toxins were discovered. The development of methods for the chemical analysis of mycotoxins in feeds and animal tissues has contributed to an improved understanding of the dose-response relationships of farm animal diseases associated with exposure to aflatoxins, fumonisins, ochratoxin A, deoxynivalenol, zearalenone, and ergot alkaloids. In all cases the effect of mycotoxins on animal performance is potentially a major problem for farmers regardless of their scale of operation. Reduced growth, decreased egg and milk production, lower reproductive efficiency, and increased susceptibility to stress are all potentially devastating consequences of mycotoxin exposure. Thus, being aware of the outward signs that might signal the involvement of a mycotoxin in an animal performance problem is the first step to minimizing potential adverse impacts. The target organ affected can provide important clues to involvement of a specific mycotoxin, in which case understanding the toxicokinetics and toxicology will assist in minimizing the cost and maximizing the effectiveness of interventions. The primary objective of this chapter is to provide information that will aid in the field identification of the possible involvement of a mycotoxin in an animal production problem. In conjunction with the information provided in the other chapters, this information will assist farmers in making decisions that will minimize losses due to diseases induced by mycotoxins.

Diplonine, a neurotoxin isolated from cultures of the fungus Stenocarpella maydis (Berk.) Sacc. that induces diplodiosis

Diplodiosis is a neuromycotoxicosis of cattle and sheep caused by ingestion of maize infected with the ear-rot fungus Stenocarpella (= Diplodia ) maydis . Apart from ataxia, paresis, and paralysis, the toxin is responsible for stillbirths and neonatal losses characterized by the presence of spongiform degeneration in the white matter of the brain in the offspring of dams exposed to infected maize cobs. In the present study a toxin, named diplonine, which induced neurological signs in guinea pigs resembling some of those occurring in cattle and sheep, was isolated from S. maydis cultures. Purification of diplonine was achieved by methanol extraction followed by chromatographic separation on silica gel and RP-18 stationary phases. The structure and relative configuration of diplonine were defined by analysis of NMR and MS data as (S)-2-amino-2-[(1R,2S)-1-hydroxy-2-methylcyclopropyl]acetic acid or the (S)-2-amino-2-[(1S,2R)-diastereomer.

Evaluation of the detoxifying effect of yeast glucomannan on aflatoxicosis in broilers as assessed by gross examination and histopathology

We evaluated the efficacy of yeast glucomannan (Mycosorb), incorporated into the diet at 0.5 and 1 g/kg, in reducing the detrimental effects of 2 mg aflatoxin/kg diet on growing broiler chicks from 1 to 21 d of age. A total of 240 male broiler chicks (Ross-308) was divided into 6 treatment groups [Control, Aflatoxin (AF), Yeast glucomannan (YG; 0.5 g/kg), AF plus YG (0.5 g/kg), YG (1 g/kg), and AF plus YG (1 g/kg)]. Ten chicks from each of the 6 groups were slaughtered and pathological examinations were performed on the liver, bursa of Fabricius, thymus, spleen and kidney. The aflatoxin treatment caused moderate to severe hydropic/fatty degeneration in the hepatocytes of the liver and the tubular epithelium of the kidneys, and follicular depletion in the bursa of Fabricius, thymus and spleen. Yeast glucomannan added to the aflatoxin-containing diet at 0.5 and 1 g/kg diminished the severity of pathological changes, slightly and moderately, respectively. The number of affected organs was also reduced in the group given 1 g/kg yeast glucomannan, compared to the aflatoxin group. These results show that yeast glucomannan effectively diminished the adverse effects of aflatoxin on the pathological changes and that the higher concentration of yeast glucomannan (1 g/kg) was more effective than the lower concentration (0.5 g/kg) and itself had no adverse effect.