Is Rapeseed Oil Bad for Horses?

A Balanced Look at Nutrition and Safety

Rapeseed oil - also known as canola oil - is widely used in equine feeds as a source of fat. But you may have heard mixed opinions online: some raise concerns about its omega-3/omega-6 balance, others worry about herbicide residues like glyphosate in crop plants. So, is rapeseed oil bad for horses?

In short, no - when used appropriately in a balanced diet, rapeseed oil is not harmful and can even be a useful energy source. Understanding why this is true requires a closer look at equine lipid nutrition, how modern feed crops are grown, and how horses are exposed to various compounds in their daily diet.

Some FAQ’s on Rapeseed Oil:

Is rapeseed oil safe for horses?

Yes, rapeseed oil is safe for horses when fed in small amounts as part of a balanced, forage-based diet.

Does rapeseed oil upset gut health in horses?

In sensible quantities, rapeseed oil does not negatively affect gut health and can be safely included alongside a fibre-rich diet that supports hindgut fermentation.

Is rapeseed oil too high in omega-6 for horses?

Rapeseed oil contains more omega-6 than omega-3, but this does not pose a problem when it is fed in small amounts and the overall diet is rich in omega-3s, such as those supplied by fresh grass or forage.

Should I worry about glyphosate in rapeseed oil for horses?

Glyphosate exposure from small amounts of rapeseed oil is minimal and significantly lower than the daily exposure horses receive from forage such as hay or straw.

Is rapeseed oil worse than other oils for horses?

No. Rapeseed oil is comparable to other commonly used plant oils and can be a practical, digestible energy source when used appropriately.

Can horses get enough fat from forage alone?

Fresh grass provides natural fats and omega-3s, but some horses benefit from added oil to support energy needs without increasing starch intake.

How much rapeseed oil should be fed to horses?

Rapeseed oil should be introduced gradually and fed in small, controlled amounts appropriate to the horse’s size, workload and overall diet – up to a maximum of 500ml per day. 

Understanding Fat in the Horse’s Diet

Fat is increasingly recognised as an important energy source in equine nutrition - especially for horses in moderate to hard work, or those that don’t do well on high-starch diets. Unlike carbohydrates, fat provides a calorie-dense, cool energy source that doesn’t spike blood sugar.

However, not all fats are the same. Two types of polyunsaturated fatty acids (PUFAs) matter most for horses:

• Omega-3 fatty acids, which support inflammatory balance and cellular function,
• Omega-6 fatty acids, which are also essential but typically more abundant in many feeds.

The ideal is not zero omega-6 and high omega-3, but a balanced profile that complements what the horse already receives from their forage.

Rapeseed Oil and the Omega-3/Omega-6 Profile

Rapeseed oil is often criticised for having a higher proportion of omega-6 fats compared to omega-3 fats. In laboratory analyses, rapeseed oil generally contains:

• moderate levels of omega-3 (alpha-linolenic acid),
• relatively higher omega-6 (linoleic acid),
• and a high overall unsaturated fat content.

Some online commentary has labelled omega-6 dominant fats as “pro-inflammatory”. But in horses, the situation isn’t so black and white.

Key points to consider:

Horses evolved to eat high-fibre diets, not high oil diets. Their natural digestive system handles fats differently from humans or carnivores.

Most horses on pasture receive an abundance of omega-3 from grass, especially in spring and summer. Fresh grass is one of the richest natural sources of omega-3 for horses.

Even when grass is not available (e.g., winter), good-quality forage still supplies a background of fibre and nutrients that support gut health and lipid metabolism.

In this context, using small amounts of rapeseed oil - for palatability, as a calorie supplement, or to assist in weight gain where needed - is not likely to disrupt the overall omega profile when the rest of the diet includes rich omega-3 sources like grass, varied forage, or specialised supplements designed to boost omega-3 intake.

What About Glyphosate and Crop Residues?

Glyphosate - a broad-spectrum herbicide used in many cereal and oilseed crops (including linseed) - is understandably a concern for many horse owners. It’s always sensible to consider what your horse is consuming. But several important points help put this into perspective:

Everyday Exposure from Forage

Whether your horse is eating hay, straw, pasture grass or conserved forage, they are already exposed to trace residues of various environmental compounds - including herbicides, fungicides and naturally occurring plant alkaloids. Neighbouring farmers spraying crops can allow chemicals to travel in the wind or be transported by animals, insects and birds. These are generally at extremely low levels and fall within regulatory safety margins.

Hay and straw, for example, can contain residues from:

• herbicides applied during crop production,
• environmental dust,
• soil microbes,
• and natural secondary plant compounds.

Current scientific risk assessments, including those used by EFSA and other food safety authorities, indicate that low-level exposure through animal feed is not considered a health risk when below regulatory limits.

Glyphosate in Rapeseed Oil

Rapeseed oil is extracted from the seeds of the rapeseed plant. During oil extraction and processing, most soluble compounds - including herbicide residues - are left behind in the press cake or removed. The refined oil itself contains very low to negligible levels of water-soluble residues such as glyphosate. It has been shown in multiple studies to be so miniscule that it is below detectable levels.

Regulatory oversight and testing are designed to ensure that edible oils (whether for humans or animals) meet strict safety standards. This means that the additional glyphosate exposure from a tablespoon or two of rapeseed oil is minuscule compared with the total daily intake of chemicals and toxins horses receive from their forage.

The Bigger Picture: Daily Toxin Exposure

It’s easy to focus on one ingredient, but horses are exposed to many compounds in their daily diet and environment, including:

• dust and molds from hay or straw,
• mycotoxins from fungal contamination,
• environmental pesticides from pasture (whether intentionally applied or carried in from neighbouring fields)
• bacterial metabolites in the hindgut,
• naturally occurring plant alkaloids in grazing weeds.

Importantly:

The horse’s digestive system - especially the hindgut microbiome  -  plays a central role in processing and detoxifying many compounds before they are absorbed.

A resilient and diverse microbiome supports healthy fermentation, energy capture, immune function and helps maintain consistent digestion in the face of many dietary inputs.

In comparison, the additional load from adding a small volume of rapeseed oil to a horse’s diet is extremely low and does not meaningfully increase risk when part of a balanced, forage-rich feeding programme. The benefits outweigh any potential negatives.

 

So Is Rapeseed Oil Bad for Horses?

No - it is not inherently bad when used appropriately.

Here’s the practical takeaway for owners:

Rapeseed oil can be a safe part of an equine diet when:

• fed in small, controlled amounts,
• the horse’s diet is otherwise rich in quality forage,
• there is adequate omega-3 supply from fresh grass or other sources,
• it complements a diet balanced for energy, vitamins and minerals.

Cautions to keep in mind

Do not substitute oil for forage - the horse’s digestive system is designed to run on fibre.

Sudden large increases in oil intake can disrupt gut microbiome and cause loose stools and discomfort if introduced too quickly.

Always balance oil supplementation within the context of total daily calories.

 

Balancing Oils with Gut Health in Mind

A healthy hindgut microbiome depends on:

• steady forage intake,
• microbial diversity supported by fibre,
• minimal abrupt changes in diet.

Small amounts of rapeseed oil do not disrupt these fundamentals. In fact, when calorie density is required (e.g., for hard-working horses or those needing weight gain), adding rapeseed oil can:

• provide a concentrated energy source,
• reduce reliance on high-starch feeds that can be more disruptive to hindgut microbes.

When combined with good pasture, quality hay and a balanced feeding strategy, rapeseed oil fits comfortably into a gut-friendly diet.

 

Conclusion: A Balanced, Evidence-Based Perspective

Concerns about rapeseed oil - whether related to fatty acid profile or crop residues - are understandable, but when examined in context, they do not stand up as reasons to avoid it entirely.

Rapeseed oil is a safe and useful dietary component when:

• fed in sensible amounts,
• included within a diet prioritising forage and omega-3 sources,
• balanced for the horse’s daily energy and digestive needs.

Horses are exposed to a wide variety of compounds through forage, pasture and environment. The tiny amount of oil added for nutritional support represents a negligible risk, and when managed well, fits within a strategy that supports both gut health and overall wellbeing.