Probiotic bacteria and yeasts adsorb aflatoxin M1 in milk and degrade it to less toxic AFM1-metabolites.

The presence of contaminants such as aflatoxins (AFs) in dairy products constitutes a serious risk to the health of consumers, especially children who are most sensitive to the adverse effects of AFs. The presence of Aflatoxin M1 (AFM1) in milk is a public health problem since dairy products are massively consumed worldwide. The aim of the present work was to select microorganisms capable of reducing AFM1 entry into the food chain through adsorption/degradation strategies. Moreover, the toxicity of AFM1 degradation products was evaluated. All tested strains had the capacity to adsorb 19%-61% AFM1 in milk. These strains also had the ability to degrade AFM1 into metabolites less toxic than the original toxin. Moreover, this is the first study to report harmless and probiotic Pediococcus pentosaceus and Kluveromyces marxianus have the ability to adsorb and degrade AFM1 to less toxic metabolites in milk.

Use of yeast (Pichia kudriavzevii) as a novel feed additive to ameliorate the effects of aflatoxin B1 on broiler chicken performance.

The aim of this study was to evaluate the efficacy of autochthonous Pichia kudriavzevii as a novel bioadsorbent for aflatoxin B1 (AFB1). The selection of this yeast was based on the AFB1 adsorption capacity previously demonstrated in vitro (Magnoli et al. 2016). One-day-old Cobb broilers (n = 160) were randomly assigned to four dietary treatments (T1: basal diet (B); T2: B + 0.1% yeast; T3: B + AFB1, 100 µg/kg; T4: B + 0.1% yeast + AFB1, 100 µg/kg). Performance parameters (average daily weight gain body, average daily consumption, feed conversion ratio, carcass weight, and dead weight), biochemical parameters (albumin, globulin, and albumin/globulin), liver pathological changes, and AFB1 residual levels in the liver and excreta were evaluated. Significant differences (P < 0.05) in performance parameters were observed among treatments and controls: T3 group showed the lowest average daily body weight gain value while in T4 group, the value of this parameter increased significantly (P < 0.05). T3 and T4 groups showed the lowest and highest values for average daily feed consumption, respectively. The feed conversion ratio (FC) showed no significant differences among treatments. T3 group showed the lowest dead weight and carcass weight compared with T1 group. The biochemical parameters showed no significant differences among treatments. T3 group showed macroscopic and microscopic liver changes compared to the control. Aflatoxin B1 levels (µg/g) were detected in broiler livers and showed significant differences among treatments (P < 0.05). In conclusion, native P. kudriavzevii incorporation (0.1%) in broiler diets containing AFB1 was shown to be effective in ameliorating the adverse effects of AFB1 on production.

Novel yeast isolated from broilers' feedstuff, gut and faeces as aflatoxin B1 adsorbents.

AIMS: To isolate and characterize native yeast strains from broilers' environment as feedstuff, faeces and gut, and to evaluate their binding capacity for aflatoxin B1 (AFB1 ). METHODS AND RESULTS: A total of nine yeast strains were isolated: three from feedstuff identified as Pichia kudriavzevii (2) and Clavispora lusitaniae (1), two from gut identified as Candida tropicalis and four from faeces identified as Cl. lusitaniae (3) and Cyberlindnera fabianii (1). AFB1 binding percentages varied among yeast strains and with AFB1 concentrations. To carry out adsorption studies, one strain from each genus and each origin was selected as follows: Cl. lusitaniae and P. kudriavzevii from feedstuff, Cl. lusitaniae and Cy. fabianii from faeces and Ca. tropicalis from gut. The most appropriate concentrations for cells and toxin were 107 cells per ml and 100 ng ml-1 of AFB1 respectively. All the tested yeast strains showed similar adsorption capacities independently of the origin. The adsorption isotherm studies in all yeasts assayed showed behaviour of L type or Langmuir and a varied affinity for the toxin. The stability of the AFB1 -yeast complex demonstrated the irreversibility of the binding process. CONCLUSION: Yeast strains tested in this study constitute potential AFB1 adsorbents and they possess the advantage to be native from the avian environment. SIGNIFICANCE AND IMPACT OF THE STUDY: This study makes a contribution to using native yeasts from broilers' environment for controlling chronic aflatoxicosis in avian production.

Negligible effects of tryptophan on the aflatoxin adsorption of sodium bentonite.

The main objective of this study was to determine if the competitive adsorption of tryptophan (Trp) and aflatoxin B1 (AFB1) could potentially affect the ability of a sodium bentonite (NaB) to prevent aflatoxicosis in monogastric animals. The adsorption of Trp and AFB1 on this adsorbent is fast and could be operating on the same time-scale making competition feasible. In vitro competitive adsorption experiments under simulated gastrointestinal conditions were performed. A high affinity of the clay for Trp and NaB was observed. The effect of an excess of KCl to mimic the ionic strength of the physiological conditions were also investigated. A six-times decrease in the Trp surface excess at saturation was observed. A similar behaviour was previously found for AFB1 adsorption. Taking into account the amount of Trp adsorbed by the clay and the usual adsorbent supplementation level in diets, a decrease in Trp bioavailability is not expected to occur. Tryptophan adsorption isotherms on NaB were 'S'-shaped and were adjusted by the Frumkin-Fowler-Guggenheim model. The reversibility of the adsorption processes was investigated in order to check a potential decrease in the ability of NaB to protect birds against chronic aflatoxicoses. Adsorption processes were completely reversible for Trp, while almost irreversible for AFB1. In spite of the high affinity of the NaB for Trp, probably due to the reversible character of Trp adsorption, no changes in the AFB1 adsorption isotherm were observed when an excess of the amino acid was added to the adsorption medium. As a consequence of the preferential and irreversible AFB1 adsorption and the reversible weak binding of Trp to the NaB, no changes in the aflatoxin sorption ability of the clay are expected to occur in the gastrointestinal tract of birds.

Effect of monogastric and ruminant gastrointestinal conditions on in vitro aflatoxin B1 adsorption ability by a montmorillonite.

The main objective of this study was to evaluate the interference of environment components on the in vitro evaluation of aflatoxin B1 adsorption capacity of sodium bentonite under simulated gastrointestinal conditions of monogastric and ruminant animals. Sodium bentonite showed a high aflatoxin B1 affinity with all of the assays. Langmuir or sigmoid isotherms were found in different assays. Both the affinities and the surface excesses at monolayer saturation were affected by the buffer components. The specific influence of ions in each buffer solution was investigated. A significant decrease in the surface excess at monolayer saturation was observed under ionic strength control. A change in the isotherm shape from sigmoidal to Langmuir was observed with the increase in the sodium chloride concentration. This was attributed to the decrease in the importance of lateral interaction between adsorbed toxin molecules compared with surface-molecules interactions under a high salt coverage. The presence of rumen fluid components in the adsorption environment decreased the aflatoxin B1 maximum adsorption capacity of sodium bentonite. Despite the high affinity of this adsorbent to capture aflatoxin B1, different substances present in the environment could affect the adsorption capacity, at least at low toxin concentrations that mimic chronic exposure. The environment of the gastrointestinal tract, in either monogastric or ruminant animals, affect in vivo aflatoxin B1 adsorption by sodium bentonite and should be taken into account when an in vitro performance evaluation is done.

Combined effects of aflatoxin B1 and corticosterone treatment on selected performance indices and liver histopathology in Japanese quail.

Animal feed may be contaminated with different mycotoxins, with aflatoxin B(1) (AFB(1)) being a very common and toxic compound. Considering that birds normally have to cope with different stressful situations at the same time, the present study aims to evaluate the effects of feed contamination with AFB(1) in combination with corticosterone treatment in drinking water (a model to induce physiological stress in birds) on selected performance indices: BW, feed conversion, egg production, and macroscopic and microscopic liver alterations. At 5 wk of age, quails were randomly assigned to 1 of 6 dietary treatment groups that resulted from the combination of the presence or absence of corticosterone in drinking water (5 mg/L) with the presence or absence of AFB(1) contamination (0, 100, or 500 µg/kg). The animals remained in these treatments from 5 to 11 wk of age. There were 6 replicates per treatment, each containing 2 males and 2 females. Contamination with 100 µg of AFB(1) per kilogram of feed induced no changes in BW, feed conversion, and egg production parameters. Quail fed with 500 µg of AFB(1) per kilogram of feed showed significant decreases in BW and feed consumption compared with their control counterparts. Corticosterone in combination with 500 µg of AFB(1) per kilogram of feed intensified the negative effects observed on BW and feed consumption and also had negative effects on feed conversion rate and egg production parameters, suggesting that the adverse effects of contamination with AFB(1) are intensified in situations of chronic stress. Quail treated with 500 µg of AFB(1) per kilogram showed hepatocytes with degree 1 and 2 lesions, and all quail treated with 500 µg of AFB(1) per kilogram of feed in combination with corticosterone showed degree 2 liver lesions (i.e., hepatocytes with fatty macro and microvacuoles and necrosis). This result is also consistent with the hypothesis that chronic stress exacerbates the effect of AFB(1) contamination. In conclusion, this study suggests that the negative effects of AFB(1) contamination are increased when overlapped with chronic stressful stimulation.

Effect of feed contamination with aflatoxin B1 and administration of exogenous corticosterone on Japanese quail biochemical and immunological parameters.

Stress is the loss of homeostasis by external forces or stressors. Manipulation, transport, contamination, and other procedures involved in production could be considered stressors. Contamination is a problem commonly faced by producers in the poultry industry. Aflatoxicosis is one of the most common infections resulting from feed contaminated with Aspergillus flavus and Aspergillus parasiticus. This study evaluated the potential effects of the combined administration of aflatoxin B(1) (AFB(1)) and corticosterone on biochemical (concentration of globulins, proteins, and albumin) and immunological (inflammatory response and heterophil:lymphocyte ratio) parameters of Japanese quail. Potential sex effects on those parameters were also considered. The provision of corticosterone in drinking water is a method used for mimicking the effects of chronic stress in avian species. At 35 d of age, 24 mixed-sex groups of 4 animals (2 males and 2 females) were housed in cages and assigned to 1 of 4 treatments: plain drinking water and laying diet, corticosterone administration in drinking water, feed contamination with AFB(1) (100 µg/kg of feed), or corticosterone plus AFB(1) administration. There were 6 cages per treatment. No significant effect of sex in any of the parameters analyzed was detected. Hypoproteinemia, hypoalbuminemia, and hypoglobulinemia were observed in animals treated with corticosterone or contaminated feed. These responses were exacerbated when the factors were combined. The immunodepressive effect of corticosterone administration was confirmed, and a higher effect was noticed when combined with the aflatoxin contamination. Aflatoxin contamination affected birds' physiology similar to a chronic stressor stimulation because it elevates the heterophil:lymphocyte ratio. This study suggests that the effects of the AFB(1) contamination are further increased when overlapped with a chronic stressful stimulation and emphasizes the importance of controlling potential stressor combinations during animal rearing to preserve not only the animal's health status but also their welfare.

Sodium bentonite and monensin under chronic aflatoxicosis in broiler chickens.

Clay feed additives have been increasingly incorporated into animal diets to prevent aflatoxicosis. Due to the nonselective nature of the binding interaction, many important components of the diets could also be made unavailable because of these feed additives. The anticoccidial monensin (MON) could also be sequestered by these clays. The use of sodium bentonite (Na-B) from a mine in the province of Mendoza, Argentina, was investigated as a sequestering agent to prevent the effects of 100 µg/kg of dietary aflatoxin B(1) (AFB(1)). In vitro studies demonstrated that the above Na-B was a good candidate to prevent aflatoxicosis. They also showed that MON competes with AFB(1) for the adsorption sites on the clay surface and effectively displaces the toxin when it is in low concentration. Even though the levels of MON in diets, approximately 55 mg/kg, are high enough to not be significantly changed as a consequence of the adsorption, they can further affect the ability of the clays to bind low levels of AFB(1). An in vivo experiment carried out with poultry showed that 100 µg/kg of AFB(1) does not significantly change productive or biochemical parameters. However, liver histopathology not only confirmed the ability of this particular Na-B to prevent aflatoxicosis but also the decrease of this capacity in the presence of 55 mg/kg of MON. This is the first report stressing this fact and further research should be performed to check if this behavior is a characteristic of the assayed Na-B or of this type of clay. On the other hand, the presence of MON should also be taken into account when assaying the potential AFB(1) binding ability of a given bentonite.

Effect of low levels of aflatoxin B1 on performance, biochemical parameters, and aflatoxin B1 in broiler liver tissues in the presence of monensin and sodium bentonite.

Aflatoxins (AF) are a major problem in broiler production and are significant economic and public health burdens worldwide. A commercial sodium bentonite (Na-B) adsorbent was used to prevent the effect of AF [50 µg of aflatoxin B1 (AFB1)/kg of feed] in broiler productivity, biochemical parameters, macroscopic and microscopic liver changes, and AFB1 liver residues. The influence of Na-B (0.3%) and monensin (MON, 100 mg/kg), alone or in combination, was investigated in depth. The dietary treatments were as follows: treatment (T) 1: basal diet (B); T2: B + MON; T3: B + Na-B; T4: B + Na-B + MON; T5: B + AFB1; T6: B + AFB1 + Na-B + MON; T7: B + AFB1 + MON; T8: B + AFB1 + Na-B. Birds were fed dietary treatments for 28 d (d 18 to 46). No significant differences (P < 0.05) were observed among treatments with respect to broiler performance, biochemical parameters, or relative liver weights. With the exception of T8, all livers showed histopathological alterations, with accumulation of fat vacuoles. The normal appearance of livers from T8 showed the protective effect of Na-B against aflatoxicosis. The residual AFB1 levels in livers from T5 to T8 ranged from 0.2 to 1.0 ng/g and were higher in livers from T6 (P < 0.05). Results of this study indicate a competition between AFB1 and MON for adsorption sites on Na-B when feed contains low levels of the toxin, indicating a nonselective adsorption capacity of this particular Na-B. In addition, significant levels of AFB1 in livers indicate that this determination is an important technique not only for diagnosis of aflatoxicosis in broilers, but also for quality control of avian products.