Zoila Coloma Adaniya MV. MSc (Lima – Perú)
General Manager – ZC Consulting.
Why is it so complicated to control mycotoxins?
The mechanism through which mycotoxins generate their toxic effects isn’t entirely elucidated, due to their chemical structures and target organs. There can be several responses depending on:
Additionally, different responses in individuals from the same population have been observed.
Most mycotoxins can cause lipid peroxidation, damage in the function and the structural membranes of cells, and induce apoptosis. Additionally, they can also lead to immunosuppression, hyperestrogenism, hepatotoxicity, nephrotoxicity, neurotoxicity and genotoxicity (Mallmann y Dilkin, 2007; Tabbu, 2015).
We know that, in natural conditions, we can find low to moderate levels of contamination, which makes it more challenging to recognize the effects associated with chronic intoxication.
Which is the possible economic impact of mycotoxins in animal production?
According to Naehrer (2012), diagnosing mycotoxicosis is hindered by the variations in symptoms, target organs, and pathological lesions. The intensity of the effects is influenced by:
Aflatoxins (AF) are considered carcinogenic, hepatotoxic, mutagenic, and immunosuppressive.
Reports show that aflatoxins (mainly AFB1) cause complete depression of the immune system in poultry, as well as liver damage, alteration of lipid metabolism, deficient feathering, diarrhea, deficiencies in pigmentation, and loss of weight (up to an 8%).
They interfere with the synthesis of clotting factors, causing blood stains on the carcasses (Image 1), which leads to economic losses due to market rejection.
Image 1. Aflatoxins alter clotting factors, causing subcutaneous haemorrhage (Source: LAMIC).
IMPACT OF AFLATOXINS
It has been estimated that for every 35,000 broilers that consume feed contaminated with 20-60 ppb of AFB1,during the production stages, there will be losses ranging from US$ 1,000 to US$ 4,000. (Table 1). All of which without considering the logistic costs, labor costs, energy, treatments, analysis, among others.
One of the effects that are frequently observed in animals that consume diets contaminated with aflatoxins is the lack of uniformity of the batches of animals (Images 2 and 3).
Image 2. Lack of uniformity in broilers that consumed feed contaminated with aflatoxins (Source: LAMIC).
Image 3. Lack of uniformity in pigs that consumed feed contaminated with aflatoxins (Source: Mallmann and Dilkin, 2017).
In 2012, Andretta et al., reported that pigs that had ingested feed contaminated with mycotoxins resulted in 21% reduction in weight gain. In this case, deoxynivalenol (DON) and aflatoxins were the mycotoxins that mostly affected the production parameters. This could result in economic losses of over 118 thousand US$ per year per 100 sows (Table 2).
Table 2 shows that, if all the weaned pigs (28) were to reach the average market weight of 117.5 Kg LW, discounting the production costs, the income per animal would be 53.8 US$.
In contrast, due to the effect of the mycotoxins, they may only reach 79% of the average weight (92.8 Kg LW), reducing the income to US$ 11,6 per animal.
These changes in the zootechnical parameters are associated with alterations in the gastrointestinal tract that affect the absorption of nutrients, as well as the reduction of the feed ingested that can be due to the anorexic effect of DON, together with an increase of the expression of pro-inflammatory cytokines and the satiety hormone (serotonin).
An additional fact that is relevant about AFB1 is that, as it is metabolized through hydroxylation, it transforms into aflatoxin M1, becoming a contaminant when excreted in milk or urine by animals that have ingested contaminated feed (Lee et al., 2017), making it possible to intoxicate newborn animals through milk.
How do mycotoxins affect production systems that are free of antibiotic growth promotors (AGP)?
Due to the risks associated with the inadequate use of antibiotic growth promoters, the tendency is to reduce and eventually stop their use in animal production.
The gastrointestinal tract is the main entrance for most of the enteric pathogens and their toxins. AGPs are used to control the proliferation of pathogens in the intestinal tract, mainly Gram-negative bacteria such as Salmonella and E. coli. Withdrawing AGPs can increase the symptoms and susceptibility of diseases associated with the presence of mycotoxins.
Additionally, they interfere with the different defense mechanisms of the intestinal tract, such as the integrity of the epithelium, cell proliferation, the mucous layer, the production of immunoglobulins and cytokines, inducing immunosuppression and diminishment of the response to infections.
It has been reported that the ingestion of feed contaminated with DON predisposes to the appearance of necrotic enteritis.
In the small intestine, it can lead to a failure to digest nutrients and the leakage of plasmatic amino acids to the intestinal lumen, providing the ideal substrate for the proliferation of C. perfringens.
Non-cytotoxic concentrations of DON and toxin T-2 facilitate the intestinal invasion of Salmonella, increasing its passage and translocation through the intestinal epithelium (Antonissen et al., 2014).
Additionally, it has been determined that pigs that consume feed contaminated with FB1 demonstrate more severe lesions related to viral diseases, such as Porcine Reproductive and Respiratory Syndrome (PRRS) (Ramos et al., 2010).
Some mycotoxins are considered to be more relevant, mainly due to their prevalence, level and harmful effects on human and animal health.
The negative effects produced by these toxins can be observed as a reduction in animal productivity, as well as a lack of response to vaccination programs and pharmaceutical treatments.
The new trends of AGP-free production mean that to minimize the risks and the possible losses they can lead to, we must become more aware of the role that mycotoxins have in the production process and to have stricter control over the consumables, in order to minimize the risks and possible losses that these toxins could cause.