Mycotoxins are low molecular weight chemical compounds generated as secondary toxic metabolites by a wide range of fungi. These microorganisms belong to the phylum Ascomycota, commonly known as moulds, particularly the genera Fusarium, Penicillium, Alternaria and Claviceps, among others. Mycotoxins are substances which, when incorporated in low quantities, have implications for human and animal health, causing chronic and acute diseases.
According to the species, a fungus may be capable of producing a single as well as multiple toxins simultaneously. Feed contamination is particularly subject to temperature and humidity conditions, where the hottest and most humid regions are usually the most prevalent in this problem. In addition, pH, water activity, nutrients, type of substrate, physiological state of the plant, and microbial interactions are other factors that determine the concentrations of inocula in feed. In general, temperature between 10 and 40°C, pH 8.4, humidity greater than 40%, and water activity of 0.70 are the conditions in which fungi usually develop, although their active growth in the field (mycelium development phase) is optimized with temperature between 20 and 25°C, humidity greater than 70% and water activity greater than 0.85.
It is important to mention that mycotoxins can grow on feed at different times. It is estimated that about 22% develop in the pre-harvest stage, when feed maintains higher moisture concentration. The rest can be generated in the post-harvest stages, such as drying, transport and storage.
There are approximately 400 compounds identified as mycotoxins, although only a small proportion currently receive special attention in animal production. Their detection requires sampling and laboratory processing with technology of varying complexity (analytical and agglutination techniques), since they cannot be identified with the naked eye, nor do they present color or organoleptic characteristics that make them detectable in the raw materials. Feed grains that are usually affected by molds, ranked according to their incidence, are: corn, wheat, barley, rye and soybeans.
In Latin America, pig diets are implemented based on a varied integration of cereals, where the main ingredient is corn, accompanied by soybeans or other cereals such as wheat, oats or barley. Coincidentally, the raw materials composing the rations present the highest prevalence of mycotoxin contamination. These grains are equally used in the feeding of nulliparous sows, multiparous sows and fattening piglets. Therefore, the effect of mycotoxins has an impact on adequate and economically viable production.
Among the mycotoxins frequently found in feed materials for pigs that are important for their adverse effects globally are the following:
Several studies carried out over the last year (2019) determined that all the mycotoxins mentioned in this article (aflatoxins, ochratoxins, fumonisins, DON, T-2 and zearalenone) were found in corn and other cereals that constitute the raw materials used for feeding pigs, which implies that mycotoxicosis still remains one of the main current problems to be considered in animal nutrition. On a Latin American scale, Central American countries reported the highest rates of contaminated feeds with concentrations above acceptable limits (between 75 and 100%), while South American countries reported lower rates. As a reference, acceptable values set for the various mycotoxins are: Aflatoxin up to 20 ppb; Ochratoxin up to 250 ppb; Fumonisin up to 20000 ppb; T-2 up to 500 ppb; DON up to 1800 ppb and Zearalenone up to 1000 ppb.
Corn, as already mentioned, is the most important ingredient of the diets of pigs and birds in Latin America. Among the samples analyzed for this cereal, 90% were determined to be contaminated with fumonisin, followed by 56% contaminated with DON. The rest of the mycotoxins were found to be present at levels below 30% of the samples. However, for all mycotoxins tested on maize, except ochratoxin, the maximum concentrations found sometimes exceeded the average acceptable limits: aflatoxins (up to 63-fold), zearalenone (up to 2.5-fold), DON (up to 3.1-fold), T-2 (up to 1.4-fold), fumonisin (up to 8.5-fold). In another study conducted on corn samples during the years 2019-2020 in six Latin American countries (Chile, Brazil, Colombia, Argentina, Peru and Mexico), it was determined that between 84 and 100% of the samples from those regions were contaminated with fumonisin, but in none of the cases was the average acceptable limit exceeded. Exceptionally in Peru, 50% of maize samples were also found to contain DON and Zearalenone.
With respect to other cereals, it was observed that more than 50% of the samples analyzed for Latin America were found to be contaminated with aflatoxins, zearalenone and DON. The latter was the most prevalent in wheat (69%). For some mycotoxins it was even observed that the values found sometimes exceeded the average acceptable limits in raw materials, such as the case of aflatoxins (up to 0.5 times more) and DON (up to 2.8 times more). The rest remained at values below the established limits and, although they do not imply a risk of acute poisoning, chronic effects could occur in the medium and long term.
With regard to the analysis of finished feeds, it could be established that more than 40% of the samples were contaminated with zearalenone, DON and fumonisin, the latter exceeding the average acceptable limits (up to 15.2-fold). In summary, the highest risk of feed contamination in Latin America is currently given by the presence of fumonisins in the first place and DON next.
These reports have also determined that contamination of raw materials by multiple mycotoxins has been observed in 85 to 90% of the samples analyzed, and more than ten mycotoxins and metabolites per sample can be described. It is estimated that the impact of a single mycotoxin in the diet can lead to a reduction in feed consumption by up to 14%, accompanied by a weight loss of up to 17% in pigs, while multiple contamination has led to reductions of up to 42 and 45% respectively. It is estimated that the economic impact of mycotoxins in pigs can lead to a decrease in net profit/pigs in the range of $1.6-10.9.
As detailed in the previous sections, it should be stressed that the presence of mycotoxins is not an exceptional event, but rather natural in feed. One of the most commonly used methods to reduce the mycotoxin load in feed is the incorporation of sequestrants which can bind effectively to these chemical compounds, preventing their early effect and absorption in the gut. Aluminosilicates are one of the technologies implemented for this purpose, which are derived from natural clays such as bentonite.
Polysilicon is a molecule generated from the activation process of these clays. In addition to being composed of aluminum silicates, they contain calcium and sodium ions interspersed between aluminum ions, causing an increase in the distance between silicon ions, which improves their adsorption capacity. This improvement comes from the numerous free bonding points to be occupied by the mycotoxins present in feed, by establishing hydrogen bridge bonds between the hydroxyl terminals of mycotoxins and the free oxygen atoms of polysilicon.
Polysilicon confers multiple advantages. On the one hand, as it is a three-dimensional structure and has numerous junction sites, so the doses to be applied are usually reduced taking into account clay quality. It also allows binding to a wide range of mycotoxins from different groups, which is of great relevance, bearing in mind that, at present, approximately 90% of animal feed is contaminated with approximately ten or more toxic metabolites. Given this situation, the use of specific sequestrants would imply a low efficiency or an increase in the investment for the incorporation of other additives with wider effects. Finally, polysilicon allows safe handling due to its zero toxicity, easy incorporation to feed and high stability to different pHs of the gastrointestinal tract with low desorption rates.
AISEN is the line of mycotoxin-sequestering products elaborated by MINERVET S.A. They are polysilicon-based sequestrants produced from food grade natural bentonite clays with a high degree of purity. The tests carried out with AISEN have determined its high adsorption efficiency for a wide range of mycotoxins. For raw materials contaminated with mycotoxins (Aflatoxins: 140 ppb; Ochratoxin: 500 ppb; Zearalenone: 3000 ppb; DON: 3000 ppb; T2: 800 ppb) the following final adsorption efficiency rates were obtained:
|Mycotoxin||Adsorption Efficiency (%)|
It has also been observed for tests carried out on pigs that, when faced with diets contaminated with mycotoxins, animals that were given the AISEN product had an average daily weight gain improvement of 17% in cases of contamination with aflatoxins and of 36% in cases of rations with high concentrations of zearalenone and DON. In the case of contamination with high levels of fumonisin, fattening pigs supplemented with AISEN showed a conversion rate of between 7 and 10% improvement compared to animals without any treatment.
The use of AISEN will make it possible to reduce the risks posed by mycotoxins present in raw materials intended for animal feed, not only in relation to the health status of animals, but also in the positive impact on the maintenance and improvement of indices related to the system’s production and profit. At present, Latin America has the possibility to look at the world and be a strong competitor if it takes advantage of the present opportunities.
China is the country with the largest number of pigs in the world, with an estimated annual production of 441 million animals by the beginning of 2019. However, with the advance of the epidemic related to African swine fever, it is estimated that in the last year, China suffered the loss of between 150 and 200 million heads. It is estimated that its annual production of 54 million tons could have decreased by 30%.
Given this situation, China has looked to the Latin American market as a potential source of resources to make up for the drop in production. In Argentina, for example, a bilateral agreement has enabled investments of nearly 27 billion dollars in the next 4 to 8 years to generate exports of pork and pork products for more than 20 billion dollars annually. Therefore, Argentina would go from producing 6 million to approximately 100 million heads per year within the next 5 to 8 years.
These changes have also had an impact on Chile. For the first month of 2020, pork exports grew by 72%, generating an increase in profits of $34.9 million more than the previous period. Peru and Colombia have also seen an opportunity in this situation. In late 2019 and early 2020, they found themselves negotiating the entry of pork to China. The production of pork in these countries is linked to its consumption, which is estimated at about 7 kg per person for Peru and 11.2 kg for Colombia, who seek to supply and contribute to the Asian country that maintains an annual consumption of 82kg per capita. China became Brazil’s main export destination during 2019 with an increase of 21,100 tons, representing a 51% growth in average volume. Mexico, which is the eighth largest exporter of pigs worldwide, has sought to double them in the face of the crisis in China, where it is estimated to increase from 30,000 to 60,000 tons due to the growing demand in recent months.
Dr. Martin Quero
Veterinary Area Manager