Biochemical and physiological responses of growing chickens and ducklings to dietary aflatoxins

Role of clay in detoxification of aflatoxin B1 in growing Japanese quail with reference to gender

The present study investigated the influence of the quail diet polluted with aflatoxin B₁ (AFB₁) and its detoxification by using clay as a feed additive on the growth performance and some blood biochemical components of growing Japanese quail with reference to sex. A total number of 120 Japanese quail chicks (1 week old), was randomly divided into 10 groups (24 chicks/ group). A 5 × 2 factorial arrangement experiment was performed and included five levels of AFB₁ (0 ppm, 1 mg/kg AFB₁, 1 mg/kg AFB₁ + 1% clay, 2 mg/kg AFB₁ and 2 mg/kg AFB₁ + 1% clay) and two sexes. Birds fed with aflatoxin free diet had significantly (P ≤ 0.05 and 0.01) higher final live body weight, weight gain and lower mortality rate than the other groups. Addition of 1% clay significantly (P ≤ 0.05 and 0.01) improved the growth performance traits and diminished aflatoxin effect when compared to groups without the addition of clay. Obtained results indicated significant (P ≤ 0.05) differences between the two sexes in their response to aflatoxicosis in the final live body weight and weight gain. Our results showed significant (P ≤ 0.01) changes in all blood biochemicals (total protein, albumin, globulin, total cholesterol, creatinine, uric acid) and activities of serum enzymes studied due to the toxicity of AFB₁. Conclusively, the consumption of polluted diets with AFB₁ caused deleterious effects on the growth performance and blood biochemicals components of Japanese quail, while dietary addition of natural clay to the diet of growing Japanese quail caused beneficial effects.

The Mechanism Underlying the Extreme Sensitivity of Duck to Aflatoxin B1

Most metabolites of aflatoxin B1 (AFB1), especially exo-AFB1-8,9-epoxide (AFBO), can induce the production of reactive oxygen species (ROS) to vary degrees, causing oxidative stress and liver damage, and ultimately induce liver cancer in humans and animals. Duck is one of the most sensitive animals to AFB1, and severe economic losses are caused by duck AFB1 poisoning every year, but the exact mechanism of this high sensitivity is still unclear. This review highlights significant advances in our understanding of the AFB1 metabolic activation, like cytochrome P450s (CYPs), and AFB1 metabolic detoxification, like glutathione S-transferases (GSTs) in poultry. In addition, AFB1 may have other metabolic pathways in poultry, such as the mutual conversion of AFB1 and aflatoxicol (AFL) and the process of AFBO to produce AFB1-8,9-dihydrodiol (AFB1-dhd) and further metabolize it into detoxification substances. This review also summarized some exogenous regulatory substances that can alleviate AFB1-induced oxidative stress.

Growth, bioluminescence and shoal behavior hormetic responses to inorganic and/or organic chemicals: a review

A biphasic dose response, termed hormesis, is characterized by beneficial effects of a chemical at a low dose and harmful effects at a high dose. This biphasic dose response phenomenon has the potential to strongly alter toxicology in a broad range. The present review focuses on the progress of research into hormetic responses in terms of growth (in plants, birds, algae and humans), bioluminescence, and shoal behavior as end points. The paper describes how both inorganic and organic chemicals at a low dose show stimulatory responses while at higher doses are inhibitory. The article highlights how factors such as symbiosis, density-dependent factors, time, and contrasting environmental factors (availability of nutrients, temperature, light, etc.) affect both the range and amplitude of hormetic responses. Furthermore, the possible underlying mechanisms are also discussed and we suggest that, for every end point, different hormetic mechanisms may exist. The occurrences of varying interacting receptor systems or receptor systems affecting the assessment of hormesis for each endpoint are discussed. The present review suggests that a hormetic model should be adopted for toxicological evaluations instead of the older threshold and linear non-threshold models.

Integrative toxicopathological evaluation of aflatoxin B₁ exposure in F344 rats

In this study, male F344 rats were orally exposed to a single dose of aflatoxin B₁ (AFB₁) at 0, 50, 250, or 1,000 µg/kg body weight (BW) or repeated dose of 0, 5, 10, 25, or 75 µg/kg BW for up to 5 weeks. Biochemical and histological changes were assessed together with the formation of AFB1-lysine adduct (AFB-Lys) and liver foci positive for placental form glutathione S transferase (GST-P⁺). In single-dose protocol, serum aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP) showed dose-related elevation, with maximal changes observed (>100-fold) at day 3 after treatment. Animals that received 250 µg/kg AFB₁ showed concurrent bile duct proliferation, necrosis, and GST-P⁺ hepatocytes at 3 day, followed by liver GST-P⁺ foci appearance at 1 week. In repeated-dose protocol, bile duct proliferation and liver GST-P⁺ foci co-occurred after 3-week exposure to 75 µg/kg AFB₁, followed by proliferation foci formation after 4 week and dramatic ALT, AST, and CK elevations after 5 weeks. Liver GST-P⁺ foci were induced temporally and in a dose-related manner. Serum AFB-Lys increased temporally at low doses (5-25 µg/kg), and reached the maximum after 2-week exposure at 75 µg/kg. This integrative study demonstrated that liver GST-P⁺ cells and foci are sensitive biomarkers for AFB₁ toxic effect and correlated with bile duct proliferation and biochemical alterations in F344 rats.

Toxicology, environmental health, and the "One Health" concept

The One Health concept promotes collaboration among veterinarians, physicians, scientists, and other professions to promote human, animal, and ecosystem health. One Health illustrates the interconnectedness and interdependence of human, animal, and ecosystem health. This concept has traditionally focused on zoonoses that are infectious diseases, not on chemical- or poison-related illnesses in animals and their relationship to the detection and prevention of human illness. The purpose of this article is to describe key experiences of scientists in the Health Studies Branch within the National Center for Environmental of Health of the Centers for Disease Control and Prevention in which the study of animal illness facilitated a public health investigation into an outbreak of chemical-associated human disease. The experiences highlight how utilizing the One Health approach may improve chemical-associated outbreak investigations and facilitate appropriate intervention strategies. An appropriate One Health approach in toxicology and environmental health in outbreak settings should include consideration of the common environments and food sources shared by humans and animals and consideration of the potential for contaminated animal products as food sources in human exposures.

Evaluation of the ability of a feed additive to ameliorate the adverse effects of aflatoxins in turkey poults

1. A study was conducted to evaluate the possible protective effect of a feed additive containing aluminosilicate and phytogenic substances against the adverse effects of aflatoxins in turkey poults. 2. Dietary treatments (6) were given to turkey poults from d 1 to d 42 of age. From d 1 to 21 the dietary treatments were as follows: 1, negative control, no aflatoxins or feed additive added; 2, feed additive control, 1 kg/t feed additive, no aflatoxins; 3, 250 ppb (microg/kg) aflatoxins, no feed additive; 4, 250 ppb aflatoxins + 1 kg/t feed additive; 5, 500 ppb aflatoxins, no feed additive; and 6, 500 ppb aflatoxins + 1 kg/t feed additive. From d 22 to 42, the dietary concentration of the feed additive was increased from 1 to 2 kg/t in all treatment groups receiving the feed additive (2, 4 and 6), while keeping constant the dietary concentrations of aflatoxins. 3. Aflatoxins at 250 ppb did not cause adverse effects on performance but affected certain toxicopathological parameters. At 500 ppb, adverse effects on performance and several toxicological parameters were observed. 4. Some of the adverse affects were partially or completely overcome by supplementation with the feed additive, including amelioration of the performance parameters, suppression of mortality and correction of the immunological alterations induced by the exposure to the aflatoxins.

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 sodium bentonite on the performance and blood variables of broiler chickens intoxicated with aflatoxins

1. This study was conducted to evaluate the protective effect of natural sodium bentonite (NaB) in the prevention of toxic effects of aflatoxins. Five hundred and twenty-eight 1-d-old Ross male broiler chickens were housed in pens (22 chickens per pen) for 42 d. There were 3 inclusion rates of NaB (0, 2.5, and 5 g/kg) and 2 of aflatoxins (0 and 3 mg/kg food). Each treatment had 4 replicates of 22 chickens. 2. All chickens treated with aflatoxin and without bentonite were adversely affected. NaB treatment at 5.0 g/kg improved body weights at 42 d of age by 31.3%, increased food intake by 23.8% and improved productive efficiency by 40.1%. Weights of liver, heart, pancreas and crop and biochemical variables were not affected by dietary NaB. However, serum phosphorous concentration was reduced by 30% compared with chickens that received aflatoxin. 3. NaB caused no adverse effects on chickens that did not receive aflatoxin. 4. It is concluded that NaB at pH 7.9 partially neutralises the effects of aflatoxins on broiler chickens when included at 5.0 g/kg in the diet.

Study on effects of feeding laying hens on separate mycotoxins (aflatoxins, patulin, or citrinin)-contaminated diets on the egg quality and tissue constituents

Four groups (each of 8 laying hens plus one cock) were offered commercial laying mash contaminated with 100 ppb of aflatoxins, citrinin, patulin or uncontaminated (control) for 6 weeks. The mycotoxin-contaminated diets led to some significant changes in egg characteristics and composition such as ash and calcium contents of the egg shell. The noticeable changes including also the relative weights of adrenal glands. Blood profile reflected too alterations (P greater than 0.05) in urea content and activity of both glutamic oxaloacetic transaminase and alkaline phosphatase as well. The mycotoxins affected significantly moisture and fat contents of the red muscle and protein content, texture and percentage of lean meat in both types of muscles (red and white). Patulin toxicosis was responsible for the strongest alterations in moisture, fat and vitamin A contents of the laying hen's liver and for the lowest calcium content of egg shell besides the shape alteration of the eggs. Laying hens fed on aflatoxin-contaminated diet produced hatched chicks with higher weight (P less than or equal to 0.05) than those from the controls. Citrinin residues were 10 ppb in the fresh muscles and egg yolk and 6 ppb in egg white.