The preventive effect and mechanisms of adsorbent supplementation in low concentration aflatoxin B1 contaminated diet on subclinical symptom and histological lesions of broilers

This study aimed to investigate the subclinical symptom and histological lesions of 21-day-old and 42-day-old broilers exposure to low concentration aflatoxin B1 (AFB1), and the preventive effect with adsorbent (Toxo-MX) supplementation. A total of 576 one-day-old Arbor Acres broilers were randomly allotted into 6 treatments 8 replicates and 12 birds per cage, fed with 0 ppb, 60 ppb and 120 ppb AFB1 contamination diet with or without Toxo-MX supplementation. Results showed both 60 ppb and 120 ppb AFB1 contamination significantly reduced growth performance in 21-day-old broilers (P < 0.05), but not in 42-day-old broilers (P > 0.05), however, AFB1 contamination in diet caused a higher feed to gain ratio (P < 0.05). Broilers of 21-day-old exposure to 60 ppb and 120 ppb AFB1 increased mRNA expression of hepatic inflammatory cytokines, and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity (P < 0.05), 42-day-old broilers showed a same change in 120 ppb but not in 60 ppb of AFB1 contamination (P < 0.05). mRNA expressions of clauding-1, Zonula occludens-1 (ZO-1), and occludin decreased, but Bax, Bcl-2, and caspase-3 increased in 21-day-old broilers exposure to 60 ppb and 120 ppb AFB1 (P < 0.05), broilers of 42-day-old resisted on intestinal aflatoxicosis impairment against 60 ppb AFB1 contamination (P < 0.05), but not in 120 ppb (P < 0.05). Toxo-MX supplementation significantly reversed the detrimental effects on growth performance in both age broilers and reduced the accelerated feed to gain ratio caused by AFB1 (P < 0.05). Intestinal mRNA expression of tight junction and apoptotic genes in both age broilers were recovered by Toxo-MX supplementation (P < 0.05). However, Toxo-MX did not restore the accelerated expression of hepatic inflammation cytokines and SOD, GSH-Px in 120ppb AFB1 group (P < 0.05). The data demonstrated that diet supplementation with Toxo-MX reversed the detrimental effect on growth performance and intestine in broilers exposure to 60 ppb and 120 ppb AFB1. However, did not completely recovered hepatic inflammation induced by AFB1.

Caffeic acid mitigates aflatoxin B1-mediated toxicity in the male rat reproductive system by modulating inflammatory and apoptotic responses, testicular function, and the redox-regulatory systems

Aflatoxin B1 (AFB₁ ) is a toxic metabolite of public health concern. The present study investigates the protective effects of caffeic acid (CA) against AFB₁ -induced oxidative stress, inflammation, and apoptosis in the hypothalamus, epididymis, and testis of male rats. Five experimental rat cohorts (n = 6) were treated per os for 28 consecutive days as follows: Control (Corn oil 2 ml/kg body weight), AFB1 alone (50μg/kg), CA alone (40 mg/kg) and the co-treated rat cohorts (AFB₁ : 50μg/kg + CA1: 20 or 40 mg/kg). Following sacrifice, the biomarkers of hypothalamic, epididymal, and testicular toxicities, antioxidant enzyme activities, myeloperoxidase (MPO) activity, as well as levels of nitric oxide (NO), reactive oxygen and nitrogen (RONS) species and lipid peroxidation (LPO) were analysed spectrophotometrically. Besides, the concentration of tumour necrosis factor-alpha (TNF-α), Bcl-2 and Bax proteins were assessed using ELISA. Results showed that the AFB₁ -induced decrease in biomarkers of testicular, epididymal and hypothalamic toxicity was significantly (p < .05) alleviated in rats coexposed to CA. Moreover, the reduction of antioxidant status and the increase in RONS and LPO were lessened (p < .05) in rats co-treated with CA. AFB₁ mediated increase in TNF-α, Bax, NO and MPO activity were reduced (p< .05) in the hypothalamus, epididymis, and testis of rats coexposed to CA. In addition, Bcl-2 levels were reduced in rats treated with CA dose-dependently. Light microscopic examination showed that histopathological lesions severity induced by AFB₁ were alleviated in rats coexposed to CA. Taken together, the amelioration of AFB₁ -induced neuronal and reproductive toxicities by CA involves anti-inflammatory, antioxidant, antiapoptotic mechanisms in rats. PRACTICAL APPLICATIONS: The beneficial antioxidant effects of caffeic acid (CA) are attributed to CA delocalized aromatic rings and free electrons, easily donated to stabilize reactive oxygen species. We report in vivo findings on CA and AfB1 mediated oxidative stress and reproductive dysfunction in rats. CA conjugated esters including chlorogenic acids are widely distributed in plants, and they act as a dietary source of natural defense against infections. CA can chelate heavy metals and reduce production of damaging free radicals to cellular macromolecules. Along these lines, CA can stabilize aflatoxin B1-epoxide as well and avert deleterious conjugates from forming with deoxyribonucleic acids. Hence CA, as a dietary phytochemical can protect against the damaging effects of toxins including aflatoxin B1 that contaminate food. CA dose-dependently abated oxidative, inflammatory, and apoptotic stimuli, improved functional characteristics of spermatozoa and reproductive hormone levels, and prevented histological alterations in experimental rats' hypothalamus and reproductive organs brought about by AFB1 toxicity.

Pathophysiology of avian intestinal ion transport

The gut has great importance for the commercial success of poultry production. Numerous ion transporters, exchangers, and channels are present on both the apical and the basolateral membrane of intestinal epithelial cells, and their differential expression along the crypt-villus axis within the various intestinal segments ensures efficient intestinal absorption and effective barrier function. Recent studies have shown that intensive production systems, microbial exposure, and nutritional management significantly affect intestinal physiology and intestinal ion transport. Dysregulation of normal intestinal ion transport is manifested as diarrhoea, malabsorption, and intestinal inflammation resulting into poor production efficiency. This review discusses the basic mechanisms involved in avian intestinal ion transport and the impact of development during growth, nutritional and environmental alterations, and intestinal microbial infections on it. The effect of intestinal microbial infections on avian intestinal ion transport depends on factors such as host immunity, pathogen virulence, and the mucosal organisation of the particular intestinal segment.

Aflatoxin B1 Induced Systemic Toxicity in Poultry and Rescue Effects of Selenium and Zinc

Among many challenges, exposure to aflatoxins, particularly aflatoxin B₁ (AFB₁), is one of the major concerns in poultry industry. AFB₁ intoxication results in decreased meat/egg production, hepatotoxicity, nephrotoxicity, disturbance in gastrointestinal tract (GIT) and reproduction, immune suppression, and increased disease susceptibility. Selenium (Se) and zinc (Zn), in dietary supplementation, offer easy, cost-effective, and efficient ways to neutralize the toxic effect of AFB₁. In the current review, we discussed the impact of AFB₁ on poultry industry, its biotransformation, and organ-specific noxious effects, along with the action mechanism of AFB₁-induced toxicity. Moreover, we explained the biological and detoxifying roles of Se and Zn in avian species as well as the protection mechanism of these two trace elements. Ultimately, we discussed the use of Se and Zn supplementation against AFB₁-induced toxicity in poultry birds.

Leaky Gut and Mycotoxins: Aflatoxin B1 Does Not Increase Gut Permeability in Broiler Chickens

Previous studies conducted in our laboratory have demonstrated that intestinal barrier function can be adversely affected by diet ingredients or feed restriction, resulting in increased intestinal inflammation-associated permeability. Two experiments were conducted in broilers to evaluate the effect of three concentrations of Aflatoxin B1 (AFB1; 2, 1.5, or 1 ppm) on gastrointestinal leakage and liver bacterial translocation (BT). In experiment 1, 240 day-of-hatch male broilers were allocated in two groups, each group had six replicates of 20 chickens (n = 120/group): Control feed or feed + 2 ppm AFB1. In experiment 2, 240 day-of-hatch male broilers were allocated in three groups, each group had five replicates of 16 chickens (n = 80/group): Control feed; feed + 1 ppm AFB1; or feed + 1.5 ppm AFB1. In both experiments, chickens were fed starter (days 1-7) and grower diets (days 8-21) ad libitum and performance parameters were evaluated every week. At day 21, all chicks received an oral gavage dose of FITC-d (4.16 mg/kg) 2.5 h before collecting blood samples to evaluate gastrointestinal leakage of FITC-d. In experiment 2, a hematologic analysis was also performed. Liver sections were aseptically collected and cultured using TSA plates to determine BT. Cecal contents were collected to determine total colony-forming units per gram of Gram-negative bacteria, lactic acid bacteria (LAB), or anaerobes by plating on selective media. In experiment 2, liver, spleen, and bursa of Fabricius were removed to determine organ weight ratio, and also intestinal samples were obtained for morphometric analysis. Performance parameters, organ weight ratio, and morphometric measurements were significantly different between Control and AFB1 groups in both experiments. Gut leakage of FITC-d was not affected by the three concentrations of AFB1 evaluated (P > 0.05). Interestingly, a significant reduction in BT was observed in chickens that received 2 and 1 ppm AFB1. An increase (P < 0.05) in total aerobic bacteria, total Gram negatives, and total LAB were observed in chickens fed with 2 and 1.5 ppm of AFB1 when compared with Control and 1 ppm chickens. The integrity of gut epithelial barrier was not compromised after exposure to the mycotoxin.

In vitro exposure to Escherichia coli decreases ion conductance in the jejunal epithelium of broiler chickens

Escherichia coli (E. coli) infections are very widespread in poultry. However, little is known about the interaction between the intestinal epithelium and E. coli in chickens. Therefore, the effects of avian non-pathogenic and avian pathogenic Escherichia coli (APEC) on the intestinal function of broiler chickens were investigated by measuring the electrogenic ion transport across the isolated jejunal mucosa. In addition, the intestinal epithelial responses to cholera toxin, histamine and carbamoylcholine (carbachol) were evaluated following an E. coli exposure. Jejunal tissues from 5-week-old broilers were exposed to 6×10(8) CFU/mL of either avian non-pathogenic E. coli IMT11322 (Ont:H16) or avian pathogenic E. coli IMT4529 (O24:H4) in Ussing chambers and electrophysiological variables were monitored for 1 h. After incubation with E. coli for 1 h, either cholera toxin (1 mg/L), histamine (100 μM) or carbachol (100 μM) were added to the incubation medium. Both strains of avian E. coli (non-pathogenic and pathogenic) reduced epithelial ion conductance (Gt) and short-circuit current (Isc). The decrease in ion conductance after exposure to avian pathogenic E. coli was, at least, partly reversed by the histamine or carbachol treatment. Serosal histamine application produced no significant changes in the Isc in any tissues. Only the uninfected control tissues responded significantly to carbachol with an increase of Isc, while the response to carbachol was blunted to non-significant values in infected tissues. Together, these data may explain why chickens rarely respond to intestinal infections with overt secretory diarrhea. Instead, the immediate response to intestinal E. coli infections appears to be a tightening of the epithelial barrier.

Modulation of intestinal functions following mycotoxin ingestion: meta-analysis of published experiments in animals

Mycotoxins are secondary metabolites of fungi that can cause serious health problems in animals, and may result in severe economic losses. Deleterious effects of these feed contaminants in animals are well documented, ranging from growth impairment, decreased resistance to pathogens, hepato- and nephrotoxicity to death. By contrast, data with regard to their impact on intestinal functions are more limited. However, intestinal cells are the first cells to be exposed to mycotoxins, and often at higher concentrations than other tissues. In addition, mycotoxins specifically target high protein turnover- and activated-cells, which are predominant in gut epithelium. Therefore, intestinal investigations have gained significant interest over the last decade, and some publications have demonstrated that mycotoxins are able to compromise several key functions of the gastrointestinal tract, including decreased surface area available for nutrient absorption, modulation of nutrient transporters, or loss of barrier function. In addition some mycotoxins facilitate persistence of intestinal pathogens and potentiate intestinal inflammation. By contrast, the effect of these fungal metabolites on the intestinal microbiota is largely unknown. This review focuses on mycotoxins which are of concern in terms of occurrence and toxicity, namely: aflatoxins, ochratoxin A and Fusarium toxins. Results from nearly 100 published experiments (in vitro, ex vivo and in vivo) were analyzed with a special attention to the doses used.

Gross intestinal adaptations in relation to broiler performance during chronic aflatoxin exposure

The present trial was conducted to study some morphological, digestive, and electrophysiological variables of the small intestine during chronic exposure of broilers to aflatoxin B(1) (AFB(1)). Ross 308 male chicks (7 d old) were randomly allotted to control (no AFB(1)), low AFB(1) (0.07 mg of AFB(1)/kg), or high AFB(1) (0.75 mg of AFB(1)/kg) diet. The high AFB(1) diet resulted in reduced (P ≤ 0.002) bird performance during the first 4 wk of exposure, whereas the low AFB(1) diet temporarily reduced (P = 0.034) the bird performance during wk 3 of exposure. During wk 4 of exposure, a linear (P ≤ 0.013) decrease in the unit weight of both the duodenum and jejunum was observed with increasing levels of AFB(1). This reduction in unit weight appeared to progress from the proximal (duodenum) to the distal (jejunum) small intestine with increase in the length of exposure and was not accompanied by modulation of electrophysiological variables in jejunal epithelium. Response from amiloride, a specific blocker of epithelial sodium channel, was also similar among jejunal epithelia of birds under different treatments. Interestingly, a compensatory linear (P ≤ 0.002) increase in the length of the duodenum and jejunum under high AFB(1) diets was noted to occur during wk 4 of exposure. Thus, retention of DM and nitrogen was not negatively affected by the AFB(1) diets. These data indicate that the intestine in broilers may adapt to an ongoing dietary challenge to AFB(1).

Dose-dependent increase and decrease in active glucose uptake in jejunal epithelium of broilers after acute exposure to ethanol

Little is known about the effects of ethanol on gastrointestinal tract of chicken. In this study, we investigated the effects of low levels of ethanol on electrophysiological variables of jejunal epithelium of commercial broilers. Jejunal tissues from 35- to 39-day-old broilers were exposed to either 0 or 0.1% ethanol in Ussing chambers, and electrophysiological variables were monitored for 40 min. After 40 and 60 min of incubation, glucose (20 mM) and carbamoylcholine (200 μM), respectively, were introduced into the chambers. The absolute and percent increase in short-circuit current (Isc) and potential difference (Vt) induced by glucose were increased significantly with 0.1% ethanol. There was no significant effect of 0.1% ethanol on carbamoylcholine-induced electrophysiological variables. To investigate if higher levels of ethanol have similar effects, we tested the effects of 0, 0.33, and 0.66% ethanol under similar experimental conditions until the glucose-addition step. Contrary to 0.1% ethanol, both the 0.33 and 0.66% ethanol levels significantly decreased the basal and glucose-induced Isc and Vt. Tissue conductivity remained unaffected in all cases. These results indicate that intestinal epithelia of chicken may be more sensitive to the effects of ethanol as compared with other species. This is the first report indicating dose-dependent increase and decrease in active glucose absorption in intestinal epithelia in the presence of ethanol.

Aflatoxin B(1) in affecting broiler's performance, immunity, and gastrointestinal tract: a review of history and contemporary issues

Aflatoxin B(1) is a common contaminant of poultry feeds in tropical and subtropical climates. Research during the last five decades has well established the negative effects of the mycotoxin on health of poultry. However, the last ten years of relevant data have accentuated the potential of low levels of aflatoxin B(1) to deteriorate broiler performance. In this regard, any attempt to establish a dose-effect relationship between aflatoxin B(1) level and broiler performance is also complicated due to differences in types of broilers and length of exposure to the mycotoxin in different studies. Contrary to the prevalent notion regarding literature saturation with respect to aflatoxicosis of chicken, many areas of aflatoxicosis still need to be explored. Literature regarding effects of the mycotoxin on the gastrointestinal tract in this regard is particular scanty and non-conclusive. In addition to these issues, the metabolism of aflatoxin B(1) and recently proposed hypotheses regarding biphasic effects of the mycotoxin in broilers are briefly discussed.