Most of What Your Horse Eats is Probably Contaminated

A study released in August this year in the Journal of Equine Veterinary Science into contaminants in horse feeds has found that “99 % (n = 107) of the samples tested positive for fungal metabolites, particularly Fusarium metabolites, unspecific metabolites, and pesticide residues.” 

The only sample that did not contain a contaminant was MSM (methyl sulfonyl methane), which is commonly used as a joint supplement, including in our own Sound Advice Relief Mix and Sound Advice Turmeric Joint Mix.

While this is based on European feeds, there are implications for horse owners here in Australia, as many of these feed companies are international, further the methods for processing feeds, and the equipment used for extruding and pelletising would be the same.

99% is a lot.

We have generally advised against pelleted feeds for many reasons.

Primarily because:

• they tend to contain cheaper, lower quality ingredients, bound with inflammatory oils like canola, 

• or molasses, 

• they generally don’t meet horse’s mineral requirements in practice. 

• Further, by specifically targeting feeds that supply what is missing from forage it is considerably cheaper.

• And pellets are more likely to cause choke.

But this study gives you yet another reason to avoid pelleted feeds and grain or ‘no grain’ mashes. They are full of contaminants!

Single Ingredient Feeds had Less Contamination

From the study:

"We found that single-ingredient feeds, like hay, grains, and byproducts, generally have a lower concentration and number of mycotoxins and pesticide residues than supplementary feeds. The later blend diverse ingredients and undergo more processing steps than single feeds which appears to increase the contamination risk. Still, without the detailed ingredient composition, it was not possible to identify specific ingredients of supplementary feeds that trigger the occurrence of specific contaminants. Respectively, supplementary feeds tend to have more complex profiles of fungal contaminants compared to single feedstuffs. Also, the moisture content of the different ingredients of compound feed might differ and therefore positively enhance fungal growth. This emphasizes the need for further consideration regarding horse feed composition and production processes. Further, the complexity of supplementary feeds may increase the risk of mycotoxin contamination. This might be the case because each ingredient can introduce its own set of contaminants. Additionally, the blending process can inadvertently spread contaminants from one ingredient to others. On the other hand, single ingredient products often originate from one source making quality controls easier and the process of production less complicated. This considerably reduces the risk of contamination. Still, if single products are contaminated but not controlled for contamination, it may result in ingestion of high or even lethal doses of certain toxicants."

But it’s not just bagged feeds.

One of our previous emails was about the properties of ten common pasture grasses. Many of them harbour fungi and ergots that can be harmful to your horse. Here are some examples of ubiquitous pastures and the specific fungi they contain.

Pasture Types & Fungal Sources

1. Perennial Ryegrass (Lolium perenne)

Fungal partner: Endophyte Neotyphodium lolii

Key toxins: Lolitrem B (causes ryegrass staggers), ergovaline (an ergot alkaloid) 

Risk factors: Warm, moist conditions; seed head stage; stressed plants.

2. Tall Fescue (Festuca arundinacea)

Fungal partner: Endophyte Neotyphodium coenophialum

Key toxins: Ergovaline (linked to fescue toxicosis—reproductive issues, poor milk production)

Risk factors: Late summer/autumn growth, drought stress.

3. Paspalum (Paspalum dilatatum)

Fungal partner: Claviceps paspali (ergot fungus)

Key toxins: Paspaline alkaloids (cause staggers, photosensitivity)

Risk factors: Humid, wet summers; seed head stage.

4. Fusarium-affected Grasses & Forages

Fungal genus: Fusarium spp.

Key toxins: Zearalenone, trichothecenes (DON, T-2), fumonisins

Risk factors: Prolonged wet weather, damaged or stressed plants, poor storage of hay/silage.

I don’t know about you, but I always thought silage smelt funky. We've never fed it to our horses. 

Solutions?

Keep it simple.

As mentioned above, single ingredient feeds have less contamination than pellets and mashes - they also make it much easier to balance your horse's nutrition because you know exactly what the nutritional profile of a single ingredient should be.

Once you have supplied what is missing from forage with single ingredient feeds, you can then look at supplementing what's left.

All of the herbs, spices and seeds in Sound Advice supplements are human grade. Our Himalayan Salt is human grade. All of the nutriceuticals like glucosamine and MSM are human grade. This means they have much more stringent quality control testing than animal grade products. We also source them from small, Australian, family-owned businesses wherever possible, so you can feel good about feeding Sound Advice supplements to your horse.

Then what?

Mycosorb toxin binder.

Mycosorb is a broad-spectrum binder: Targets both polar (charged) and non-polar (uncharged) mycotoxins, including pasture-based endophyte toxins and mould toxins from stored feeds.

Mycosorb A+ 1kg

Buy Now

Mode of action: Mycosorb binds toxins in the gut to reduce absorption, helping protect gut lining, immune function, and overall health.

Mycosorb A+ is a 10g per day dose. It’s $39/kg which is 100 doses, making it 39c per day. 

It's a very small investment in your horse's long-term health