Soaking feeds in extreme heat
Written by Mishel Metcalf Equine Nutritionist for Hi Form Australia 2026
Understanding the Risks
It's essential to recognise the risks associated with soaking feeds during hot weather. When soaking any type of horse feed, be cautious of the weather conditions and the temperature in the area where the feed is being soaked. Accelerated fermentation occurs on hot days.
Higher temperatures boost bacterial and yeast enzyme activity, leading to a quicker conversion of sugar, resulting in rancid and fermented feed.
How Fermentation Works
Fermentation involves tiny microorganisms, such as yeast and bacteria, breaking down sugars and carbohydrates. Fermentation generates gases and heat.
Within a horse's digestive system, fermentation is a natural process occurring in the hindgut, including the cecum and colon.
This area is teeming with beneficial bacteria, yeasts, and microbes that assist in breaking down fibrous plants such as hay and grass into volatile fatty acids (VFAs) for energy and metabolism. For these processes to work effectively, the microbiome needs to be balanced. The gut acts as a little ecosystem perfectly when fed correctly.
Signs of rancidity or premature fermentation
Feel the temperature of the feed itself. If the feed has become warm or hot, then usually it has started to ferment.
Check the smell. If it doesn’t smell like it usually does and has a vinegar or fruity smell, this is a sign that fermentation has commenced.
Look for tiny bubbles in the feed. This also indicates fermentation.
The Detrimental Effects of Pre-Consumption Fermentation
Soaking feed on a hot day can accelerate the fermentation process, leading to several issues.
Gaseous Colic (Tympany): Gases produced during fermentation are ingested by the horse, entering the stomach and digestive tract. A horse cannot burp and can not release gas.
This is incredibly painful for a horse and very serious.
An excess of gas may lead to an overload of gaseous microbes, disrupting the balance of gut microbiome and causing dysbiosis.
Dysbiosis causes a multitude of symptoms from bad behaviour, inappetence, poor performance & nervousness.
Nutrient Loss: Fermentation can diminish nutrients, leading to premature breakdown and reduced nutrient availability.
Toxicity Risks: Rancidity may result in harmful bacteria that can cause toxicities.
Horses that have digestive issues, dysbiosis, or gut health problems, BioEquus should be fed at 20 g per day as a treatment dose, reducing to 5 g per day maintenance dose, once symptoms cease, to provide prebiotic and probiotic support.
