Linseed (also known as flaxseed) is an annual crop that is grown for is oil rich seed. It is a traditional ingredient in equine rations and it has been fed to horses for many years. Providing numerous nutritional benefits, including delivering additional energy and promoting a shiny, healthy coat.

We are looking at what linseed is, what functions it performs in the equine body and the nutritional differences between different forms of linseed that are available to include to our horses rations.

What is linseed?

Linseed is classified as a lipid. Lipids are defined as being, ‘a large group of compounds that are hydrophobic or water-repelling’. (MacLeod, 2007)

The naturally-occurring lipids in forages and cereal grains exist as a mixture of ‘simple lipids’ and ‘complex lipids’. (Geor, 2013). By comparison, lipids added in to equine diets consist mostly of triacylglycerols, which are commonly referred to as ‘triglycerides’.

What function do lipids perform?

Certain types of fatty acids are essential in the ration because horses cannot synthesise them themselves within their body. These essential fatty acids are Linoleic Acid (Omega-6) and Alpha Linolenic Acid (Omega-3).

The biological impact of different types of fatty acids supplied by various lipid sources has been the subject of many studies. In particular, Omega-3 and Omega-6 fatty acids have received a lot of attention for their roles in maintaining the cell membrane and integrity, receptor and ion channel function, gene expression, neural and retinol development, correct absorption of fat-soluble vitamins (A, D, E and K), inflammation and immunity. (Geor, 2013).

Linseed, forages, fish oil and some algae, are typically rich sources of Omega-3 fatty acids, whereas cereal grains, vegetable oils and rice brans are high in Omega-6 fatty acids.

What are the nutritional benefits of feeding lipids?

Rations supplemented with lipids can deliver the following:

Increased levels of digestible energy (DE). Research has shown that lipids deliver 2.5 times more energy when metabolised compared to the same weight of cereals (Pilliner & Davies, 2004).
An increased ability for the horse to utilise body fat stores and hence, spare precious muscle glycogen stores. This is known as a ‘muscle glycogen sparing’ effect. When fed at certain levels the horse effectively becomes more efficient at mobilising, transporting and oxidising fat during exercise. This has the knock-on effect of potentially delaying the onset of fatigue. (This effect is only an advantage during low and moderate intensity exercise, however).
Delays in blood glucose decline and an accelerated rate of recovery of resting pulse and respiration rates. (Hintz et al. 1978a, cited in Frape, 2004)
Reduced heat burden for exercising horses, when compared to providing that energy from starch, since the body utilisation of the products of starch digestion produces more heat. (MacLeod, 2007)

Lipid quality

Omega-3 and Omega-6 fatty acids are present in varying amounts in all lipids. In simple terms, Omega-6 fatty acids on their own tend to aggravate inflammatory responses in the body and Omega-3 fatty acids provide balance. We should aim to be supplying at least twice as much Omega-3 as Omega-6 in a ration.

Linseed is one of the richest plant sources of Omega-3 fatty acids.

Linseed in its different forms

The main nutritional differences derive from the form in which linseed is fed – this can either be:

as a liquid (i.e., in an oil form) or,
as a solid (i.e., as a fat in the form of linseed meal).

Linseed Oil

The horse’s ability to digest lipids is highest (60 – 95% digested) when lipids are included in the ration in their liquid form, i.e., as an oil. (Marlin, 2020)

However, oils are said to add ‘empty calories’ to an equine ration, as they deliver no other nutritional benefits, (i.e., they are devoid of protein and minerals). So, ‘top-dressing’ an equine’s ration with additional linseed oil, can cause nutrient imbalances. That is why we often recommend micronized linseed.

Micronised Linseed

Micronised linseed is also known as linseed meal. Micronising is an infra-red, high-speed, high-temperature cooking process, which maintains the constituents. As such, it contains useful minerals and trace elements such as, Calcium, Phosphorus, Magnesium, Copper and Selenium, all of which are essential for metabolic processes.

When metabolised, Digestible Energy levels are high, at approx. 16 – 19 MJ/kg of DE. However, linseed meal, (unlike linseed oil) also delivers high levels of crude protein (19 - 22%).

It is virtually starch-free (less than 3%) and also contains very low amounts of sugar (less than 5%) so it is suitable for equines with clinical nutritional diseases, such as PPID / Cushing’s Disease or EMS (Equine Metabolic Syndrome). It is excellent for adding/supporting condition in these often challenging to manage cases.

The inclusion of lipid sources in horse’s rations has become commonplace. It is perhaps the biggest change to horse feeding over the last twenty years.

Micronised linseed is excellent if feeding for condition improvement.

One of the main reasons for this is that horses can metabolise lipids in their diet very well. In a recent study, adding 10% extra energy as lipid proved to be twice as effective as cereals at improving weight gain – and without any associated side-effects. (ibid., 2010)

References

Barfoot, C., (2010) Need Oiling, Horse & Rider. October 2010. Pg. 87-88.

Frape, D., (2004) Equine Nutrition and Feeding, 3rd Edition, Oxford, Blackwell Publishing.

Geor, R.J., Harris, P., Coenen, M., (2013) Equine Applied and Clinical Nutrition. London, Elsevier.

MacLeod, C., (2007) The Truth About Feeding Your Horse, London, J.A. Allen.

Marlin, D., (2020) Feed Materials In Focus – Why and How to Feed Oil to Horses, drdavidmarlin.com.