Carlos López Coello1, Juan Carlos del Río2, Enrique Morales Balderas1 and Gabriela Gómez Verduzco1
1Department of Avian Medicine and Zootechnics, FMVZ-UNAM, Mexico
2School of Advanced Studies, Cuautitlán-UNAM, Multidisciplinary Research
Unit, laboratory 14 “Food, Mycotoxins and Mycotoxicosis”
One of the major challenges faced by intensive animal production and public health is the high incidence and prevalence of fungi and their metabolites in grains and oilseeds in animal feed.
This problem is not recent, as during the Middle Ages in Europe one of the first cases of mycotoxicosis reported was attributed to the consumption of rye contaminated with Claviceps purpurea, causing the disease known as “St. Anthony’s Fever” which is characterized by a high incidence of necrotic lesions, nervous symptoms and high mortality in infants.
⇰ Its treatment was linked to rituals and religious ceremonies, and today this disease is still present, being known as ergotism.
Nowadays, some questions arise that deserve an answer, such as:
- ⇰ How far are we from those “magic and religious treatments”?
- ⇰ Are incidence and prevalence in mycotoxin reports consistently and accurately analyzed and correlated with the real situation in each case?
- ⇰ If grain cleaning is an efficient preventive measure, why hasn’t this practice spread?
Mycotoxins are toxic substances that alter cellular metabolism and cause tissue damage in the exposed body.
However, the presence of micelles is not necessarily linked to the production of mycotoxins.
It is now known that mycotoxins are not necessarily only the defence
mechanisms of toxigenic fungi. They are also normally produced and eliminated as a result of their metabolic activity and their production increases under stress.
The severity of the clinical under involving tissue lesions and metabolic disorders is influenced, among other aspects, by:
- ⇰ Species affected
- ⇰ Mycotoxin/s present and its/their concentration
- ⇰ Exposure time and its interactions
Todos estos aspectos nos que conducen a reflexionar:
- How do tissue injuries and metabolic effects
occur and how are they treated?
- What are the criteria for the application of
preventive and/or control measures?
- Can we treat the tissue injury while ignoring the
metabolic disturbance to restore health?
How much do mycotoxins cost us?
In 2003, the economic losses caused by mycotoxins in the United States of America and Canada were estimated to be US$ 5 billion.
⇰ 16 years later, they are still present despite the great advances in technological development and generation of scientific information.
There isn’t a comprehensive program in the application
of mycotoxin prevention and control measures in public
health that covers everything from plant development in the
agricultural field to finished products (milk, meat and eggs).
This circumstance makes the results of individual actions in each section inefficient and unpredictable, resulting in a variable response in parameters such as crop yield, storage losses, production parameters, immunity, disease severity or even death in humans.
It’s difficult to determine the exact cause of the alterations in production parameters because there is a close relationship between the toxic effects of mycotoxins and the ability of the fungi to decrease the nutritional quality and content of the ingredient.
Under research conditions, by controlling the amount and duration of consumption of a mycotoxin, the findings at necropsy and metabolic alterations are predictable and uniform, allowing a correlation between effect and concentration.
This definitely cannot happen under field production conditions, as several mycotoxins are present and they are not uniformly distributed in the feed. This implies variations in the amount and frequency consumed, with interaction between them and various conditions leading to different responses, even between individuals in the same flock.
A fundamental principle in research is the reproduction of results under the methodology employed. This is not easy to accomplish due to the lack of uniformity in intensive production systems.
Micotoxins in poultry
In poultry farming, the greatest economic losses are caused by the presence of:
- Ochratoxin A
- Toxin T-2
- Diacetoxyscirpenol (DAS)
- Deoxynivalenol (DON)
- Zearalenone (ZEN)
These mycotoxins can be classified as polar and non-polar, a relevant aspect when selecting products that promote mycotoxin control through inactivation or capture.
It is important to mention that these inactivating or binding products do not have an effect on mycotoxins or their metabolites circulating in the blood or stored in the tissues, which are in fact the xenobiotic agents responsible for recirculation disorders.
This complicates the accurate determination of the amount of
mycotoxins in an organism and which are responsible for the variability of productive and reproductive responses, clinical signs and injuries.
Effects of aflatoxins in poultry
The effect of aflatoxins in poultry at different ages and zootechnical classification is exemplified by the reduction of the concentration of:
- ⇰ Bile salts up to 56%
- ⇰ Digestive enzymes (amylase, trypsin and lipase) up to 35%
Taking into account that the concentration of nutrients is higher in broiler diets than in hen diets and that broiler starter diets contain more protein and less energy than finishing diets, the consumption of lipids and substrates on which these enzymes act is different:
The hepatotoxic effect generated by aflatoxins leads to alterations in protein synthesis.
On the other hand, liver function is altered by the degree of hepatic fat infiltration, depending on the case:
- ⇰ In broilers, infiltration and, in severe cases, fat degeneration is a frequent and important problem due to the high concentration of lipids in the diet.
- ⇰ In laying hens, fat infiltration is a physiological condition for the formation of the yolk.
Techniques for detecting mycotoxins
Currently, various analytical tests are used for detecting mycotoxins, such as:
- ⇰ Liquid chromatography
- ⇰ Coupled gas chromatography
- ⇰ Thin layer chromatography
- ⇰ Immuno-techniques such as ELISA
- ⇰ Immunoaffinity columns used as a preliminary purification step to later use liquid chromatography or combined with mass spectrometry (LC/MS), the latter being capable of simultaneously analysing different types of mycotoxins.
Taking into account the technology and scientific advances in the area of mycotoxins, the development of products that guarantee the capture of mycotoxins or inactivation by enzymatic action, the local and global legislative regulations, it could be asserted that the technologies for their prevention and control are available.
The answer cannot be simplistic, because each case has unique predisposing factors that interact closely with each other.
The mycotoxins analysis only represent the result and it can not be related to the time of sampling.
Even a different response can be obtained in the same sample, despite excellent sampling with the most accurate and sensitive analytical techniques because mycotoxin generation is a dynamic process.
Today’s actions are no guarantee for tomorrow’s control. Undoubtedly, analysis can be a very useful tool when used, correlated and interpreted properly together with the other factors involved. These analyses could indicate the way forward for the control and/or prevention of mycotoxicosis.
The agricultural sector can produce grains and oilseeds with or without mycotoxin contamination, a situation which does not affect the farmer, the storekeeper, the food manufacturer, the livestock producer or the final consumer to the same extent.
These sectors are an integral part of the production chain and cannot be seen as independent activities, as each one plays a role that has a positive or negative impact on production outcomes and public health.
How to establish measures to prevent mycotoxicosis?
It is clear that different conditions exist in each area of the food chain, which requires different measures, and not applying them in an integrated manner compromises the expected results throughout the production chain.
For example, cleaning the grain represents the most efficient measure to remove the broken grain, which is the main substrate for fungal growth.
There are areas that have not received the necessary attention, such as the case of feed silos on farms, where the environmental conditions of storage inevitably favour the growth of fungi and which are not under the supervision of the feed mill, regardless of the fact that, in most cases, internal cleaning is not carried out in time and with the required methodology simply because it is not possible due to the presence of feed inside.
So, let’s ask ourselves, as these questions still remain unanswered……
Are incidence and prevalence in mycotoxin reports consistently and accurately analyzed and correlated with the particular situation in each case?
If cleaning the grain is an efficient preventive measure, why hasn’t this practice spread?
Why have the cleanliness and knowledge of the micro-environmental conditions of farm silos, which represent a high risk factor when storing feed for so long, not received the required attention?