Producer > Dairy

Q.5. Strategies
(a) Preventing mycotoxin formation in crops
It is unrealistic to achieve zero contamination but there are a number of ways to minimise the risk:

• Planting insect and disease-resistant varieties and practising crop rotation
• Avoiding or minimising the effects of plant stressors that predispose to mould infestation and mycotoxin production
• Timely harvesting that avoids ensiling mature, dry forages that are difficult to pack
• Cleaning bunkers prior to use and sealing silos promptly on the day they are filled
• Inspecting bag or bunker plastic for holes regularly and sealing these promptly with proper tape
• Cleaning feed bunks and fully discarding contaminated crops

(b) Feed storage
Whilst mycotoxins may already be present in feeds before they are harvested, it is important to reduce the opportunity for mould growth and mycotoxin formation in storage.

Silages need to be effectively packed to ensure that there is no aerobic instability throughout the clamp or at feed out. Effective inoculants should be used to minimise silo losses and promote stability through rapid preservation.

Moist feeds need equally careful storage as they are very prone to heating, spoilage and mould formation. Cleaning out the bunk prior to the new load arriving is essential to lessen the likelihood of re-contamination. If they are clamped adequate sheeting and consolidation is vital to retard mould growth.

Dry feeds should be kept away from moisture and vermin, since any damage, even in storage, can allow mould growth to occur, especially in warm, damp conditions.

Despite all the best measures being taken, once the feeds are mixed together and air introduced, feeds can heat up in the feed trough. If this happens, try to feed smaller meals more often or consider a buffered propionic acid or inoculant to help keep the mix cool.

This is all common sense. Regardless of the risk of mycotoxin contamination, feeds and forages cost money and should be stored effectively.

(c) Mycotoxin Action Plan
If you are having problems that you suspect might be due to mycotoxin contamination:

1. Consult your vet and/or your feed adviser
2. Eliminate any other possible causes of the problems
3. Remove (or minimise the use of) any suspect or contaminated feeds
4. Ensure the total diet is geared to a fully functional rumen and a healthy cow.
5. Talk to your Alltech representative

(d) Feed Strategies
Mycotoxin adsorbents and binders
Speciality feed additives, known as mycotoxin adsorbents or binding agents are the most common approach to prevent and treat mycotoxicosis in animals. It is believed that the agents bind to the mycotoxin preventing them from being absorbed. The mycotoxins and the binding agent are excreted in the manure.

An effective binder or sequestering agent is one that prevents or limits mycotoxin absorption from the gastro-intestinal tract of the animal. In addition, they should be free from impurities and odours. Be aware that not all are equally effective. Many can impair nutrient utilisation and are mainly marketed, based on in-vitro data only.

There are two types of mycotoxin adsorbent/binder:

• Inorganic binders
• Organic adsorbents

Inorganic binders
Inorganic mycotoxin binders include:

• zeolites
• bentonites
• bleaching clays from the refining of canola oil
• hydrated sodium calcium aluminosilicates (HSCAS)
• diatomaceous earth
• numerous clays

These materials are often inexpensive and easy to handle. These products are traditionally mixed with compound feed at a mill or mixed on farm for home mixers. Costs are cheap but require a high inclusion rate in animals taking up valuable space in the diet. Most either only adsorb specific mycotoxins, bind minerals and vitamins, cause other health complications or due to the high inclusion rate required, are too expensive for industrial applications. However they are also non-biodegradable and can present disposal problems when fed at high levels of dietary inclusion.

The amount of organic acids in clays is often very small. Does the small amount of organic acid(s) really work in inhibiting moulds? The answer is NO; and it can actually do more harm than good:

The small amount of acids quite often has no effect. Worst of all, if the acids do work, due to such small amounts, they are not enough to kill the mould. Instead, the acids change the pH of the environment and bring pH stress to the moulds. The pH stress can actually stimulate the moulds to produce MORE mycotoxins (REMEMBER, mycotoxins are the secondary metabolites from moulds produced due to stress from environmental factors, such as pH).

Organic Adsorbents
Organic mycotoxin adsorbents include:

• fibrous plant sources such as:
  • oat hulls
  • wheat bran
  • alfalfa fibre
  • extracts of yeast cell wall
  • cellulose
  • hemi-cellulose
  • pectin

Such materials are biodegradable but can, in some cases, also be sources of mycotoxin contamination. Benefits of yeast cell wall as an adsorbent are low inclusion levels in the diet, high surface area allowing for adsorption of a large number of mycotoxins and certainly no toxic contaminants.

The efficacy of glucomannan-containing yeast products as mycotoxin adsorbents in feeds has been investigated globally with several studies across all animal species [Click here to see in vivo research].

Mycotoxin adsorbents offer an attractive short-term solution to the challenge of mycotoxin-contaminated animal feeds. The only complete solution to the mycotoxin challenge will be the long-term goal of eliminating mycotoxins from the food and feed chains through improved quality control based on better analytical techniques coupled with genetic advances in plant resistance to fungal infestation.

If you are considering adding a mycotoxin adsorbent to your feed you need to look for the following:

• Proven efficacy in vivo (in the animal) as well as in vitro (in a test tube)
• Low effective inclusion rate
• Stable over a wide pH range (this is necessary so that the mycotoxin stays attached to the adsorbent throughout the gut and is excreted.)
• High affinity to adsorb low concentrations of mycotoxins
• High capacity to adsorb high concentrations of mycotoxins
• Ability to act rapidly before the mycotoxin can be absorbed into the bloodstream.

Above all, when you are considering using a mycotoxin adsorbent you need to be confident that the product has been proven to work in the animal in a commercial situation. It is extremely important that any in vitro results be supported by in vivo experiments relevant to the species being fed.