Biomin World Nutrition Forum - Mycotoxins: The feed is the variable

Feed is the most versatile variable in animal production, yet it is one of the most vulnerable to contamination. In the battle against mycotoxin-induced productivity losses, the feed really is the variable.

In his 1984 paper, ‘Determining safe levels for mycotoxins’, P.B. Hamilton, Professor of Poultry Science at North Carolina State University concluded that ‘there are no safe levels for mycotoxins.’ The fact that he continued to work on these secondary fungal metabolites and their effects on poultry metabolism and production long after he made this now famous statement illustrates just how much we had yet to learn about mycotoxins.

More than two decades later, Hamilton’s conclusions are still a relevant topic for discussion.

When ADM’s Dr. Mamduh Sifri recently brought together some of the worlds foremost experts in mycotoxins to discuss the risks facing animal production due to mycotoxins, it became clear that feed would play the central role in managing the problem.

Know your enemy

Given the diversity of the mycotoxin ‘family’ and he wide variety of symptoms its members can produce, assessing a ‘risk’ in the classical sense is difficult. Professor Johanna Fink-Gremmels has been studying mycotoxicosis for more than 25 years. As well as her post at the University of Utrecht in The Netherlands, she also holds a position within EFSA, the European body responsible for setting the legal limits for mycotoxins in feedstuffs in the European Union. Fink-Gremmels explained that the biochemistry of mycotoxins is complicated by the body’s responses to them- some even become more toxic as a result of mammalian metabolism. While the 300 or so different compounds that bear the name ‘mycotoxin’ may ‘have only one thing in common- they are all produced by moulds,’ said Fink-Gremmels; they are all capable of producing disease in animals, given the appropriate level or the appropriate species.

Professor Vincent Cheng of the National I-Lan University’s Institute of Biotechnology in Taiwan explored the clinical signs of mycotoxicosis at different levels of contamination. The first effect of mycotoxin contamination, he said, can occur at levels undetectable by routine screening. Increasing the dose, Cheng explained that the clinical signs begin with an increase in disease status. Then, ‘we will find it difficult to find effective treatments for these diseases,’ he continued. ‘Following this, we will see impaired production and reproduction,’ he said. ‘Importantly,’ he explained, ‘all of these things cause economic losses in pig and poultry production.’ In the typical commercial pig and poultry operation, inevitable stressors such as ammonium chloride levels, temperature changes or castration can exacerbate the problems caused by any mycotoxin contamination in the feed.

All animals are not equal

Just as Fink-Gremmels had established earlier in the debate that neither all mycotoxins nor all animals’ reactions to them could be described as ‘equal’, Dr. Gonzalo Diaz, a veterinarian and toxicologist at the National University of Colombia, expanded on this opinion. Tackling Hamilton’s 1984 statement head-on, he expressed his disagreement. ‘Mycotoxins can be perfectly well-tolerated,’ he argued, ‘depending on the specific mycotoxin or mycotoxins involved as well as the animal species involved and some biological factors, such as age, sex, nutritional and reproductive status and so on.’ Taking some extreme illustrations, Diaz cited examples of fatalities in large numbers of pet dogs that have resulted from aflatoxin contamination of petfood. Similarly, in commercial species, ‘pigs are sensitive to all mycotoxins that are important from an economical standpoint today,’ he said. Chickens, on the other hand are very resistant to many mycotoxins, but not all birds are equal. ‘Other birds like ducks,’ he said, ‘are very sensitive to aflatoxins, followed by turkey poults, goslings, pheasants, quails and chicks.’ Furthermore, he added, ‘laying hens are more resistant than broilers.’ In light of this, he concluded that Hamilton’s statement ‘probably needs revision.’

The University of Queensland’s Professor Wayne Bryden is also adjunct professor at the Department of Poultry Science at North Carolina State University, from where Professor made the statement that formed the basis for this discussion. Supporting Diaz’ previous statements, he added ‘when you look at different breeds of chicken you get quite big variations; sometimes even a threefold difference in their susceptibility.’ Bryden also pointed out that environmental factors also have to be taken into account when trying to convert toxicological studies into practical toxicities in the field.

In-line identification still elusive

Diaz’ distinction between the ‘innate tolerance or sensitivity to every toxic substance that exists’ gave rise to a relevant question from the discussion’s audience. If it is known that a batch of corn or soybean meal is destined for broiler feed, is it really necessary to test it for aflatoxin? Diaz was clear that testing is still economically relevant. Turning the question on its head, he pointed out that the petfood industry commands the highest margins, ‘so it makes sense to test all batches of feed ingredients and divert the ones not contaminated with aflatoxin to these sectors, while the remaining ones could feasibly be used for broiler feed.’

The mycotoxin monitoring and control programme in Brazil is particularly stringent, given the importance of poultry and pig production to the country’s economy. Thus, it was appropriate that Professor Carlos Mallmann of the Federal University of Santa Maria was on hand to outline the programme’s ambitious aims and the opportunities for further development. Any programme implemented has to be not only effective, but cost-effective, Mallmann stressed. The success of any mycotoxin control programme lies in its sampling
programme. The systems of sampling used in Brazil are defined by the requirements of EU legislation. However, ultimately, said Mallmann, it is the outcome of the analysis that can make the difference between success and failure of any shipment of grain.

What do you do about contaminated feed?

While the simple, in-line system of sampling that Mallmann described in the feed mill can detect ‘a single contaminated grain in 127 tonnes of corn’, the problem of transmitting the outcome of the analysis has always been a problem in feedback reporting systems. One of the common criticisms of any legal requirement for reporting contaminants in agriculture is that by the time the results are received, the damage has already been done. In the case of mycotoxin contamination, by the time contamination has been identified, the raw material has already been incorporated into a feed and in many cases, it is already being fed. A similar situation arises further down the food chain, when trying to diagnose clinical signs or productivity losses in animals, as Wayne Bryden pointed out in his summation. ‘By the time you realise you’ve got a problem,’ he said, ‘the feed that caused the problem has already disappeared.’ Similarly, at the level of the feed, it is clear that the development of rapid, accurate and low-cost analytical techniques is a key issue that has yet to be resolved. So, until that time, how does the Brazilian feed industry use its feed effectively, given that it spends some $3.5 billion annually to test 78,000 samples of feedstuffs? While the panel agreed that feed processing was no solution against mycotoxins, Mallmann summed up current technology succinctly: ‘We put something in the feed.’

‘There are no safe levels for mycotoxins’ was the subject of a panel discussion held at the 2nd World Mycotoxin Forum, hosted by Biomin in Vienna, Austria, in September 2006.

The Panel

Chairman of the panel, Dr. Mamduh Sifri is, by his own admission, ‘very well educated’. Currently Director of Poultry, Speciality Marketing and Technical Support at Archer Daniels Midland, he is also an active member of the WPSA’s US branch, an associate editor on the editorial board of the journal of the Poultry Science Association for whom he chaired of the Informal Poultry Nutrition and Extension Symposium in Montréal in 2000.

Professor Johanna Fink-Gremmels is among the best known experts on mycotoxins in Europe, if not worldwide. Fink-Gremmels describes herself as ‘a veterinarian by training’, a profession she has practised for more than 30 years. Not only does she travel the globe imparting her expertise, but she has a position on EFSA, the European Food Standards Agency, which regulates issues in the EU pertaining to feed and food. As if this doesn’t keep her busy enough, in her day job at the University of Utrecht in the Netherlands, she tries to keep up with 10 Ph.D. students. Describing her relationship with mycotoxins, Fink-Gremmels says, ‘Research on mycotoxins has dominated my life for 25 years’.

Vincent Cheng is Professor in the Department of Animal Sciences at the National I-Lan University’s Institute of Biotechnology in Taiwan.

A veterinarian by training, Dr. Gonzalo Diaz added to his veterinary degree with an M.Sc. in toxicology and poultry pathology and a Ph.D in toxicology and nutrition. Dr. Diaz now works for the National University of Columbia, where he leads a research group whose focus is on those toxicants of natural origin that are important to monogastric nutrition.

Carlos Mallmann is Professor at the Federal University of Santa Maria’s Department of Veterinary Medicine in Brazil and is the co-ordinator of the mycotoxin analysis laboratory. He also acts as consultant to some of Brazil’s biggest feed producers, the country’s Agricultural Ministry and the FAO/UN. Having worked on mycotoxins for 28 years, his concern is specifically ‘to provide protection to farmers.’

Wayne Bryden is Professor at the University of Queensland, Australia, where he has also been head of the School of Animal Sciences since 2002. He is also adjunct professor at the Department of Poultry Science at North Carolina State University, from where Professor Hamilton (now retired) made his statement that formed the basis for the whole discussion.