Jul, 2020

What are antioxidants and free radicals?

Antioxidants are molecules, either produced in the body (e.g. glutathione peroxidase) or provided in the diet (e.g. vitamin E, vitamin C and selenium), that help to control the amount of free radicals in the body. Specific antioxidants are discussed in more detail here.

Providing the horse with dietary antioxidants, in the form of a hard feed or supplement, can help to neutralise free radicals and reduce oxidative stress, thereby helping to maintain the horse’s health, performance and well-being.

Figure 1 Oxidative Stress


When to consider dietary antioxidant support

Antioxidants are a vital part of all horses’ diets but they are particularly important for the following:

Horses receiving limited turn out and those fed predominantly hay or haylage

Horses would naturally ingest antioxidants such as vitamin E, carotenoids, flavonoids and polyphenols from fresh pasture. However, when grass is cut and made into hay or haylage the levels of antioxidants reduces considerably (Figure 1). Therefore, providing an additional source of antioxidant is recommended for horses on restricted grazing or those fed predominantly conserved forage (e.g. hay or haylage).


Oxidative stress occurs during pregnancy, particularly in the last few weeks, and in the first month after foaling. During this time, it is important to ensure that the mare has optimal levels of antioxidants including vitamin E, selenium and other essential minerals. All mares should receive a fully balanced hard feed throughout pregnancy. In addition, mares foaling outside the natural breeding season, or those for whom fresh pasture is limited, may benefit from a specific antioxidant supplement.


Sperm cells require high rates of energy production and thus produce potentially damaging free radicals. In addition, the structure of equine sperm cells makes them particularly susceptible to the damaging effects of free radicals. All working stallions will benefit from good levels of antioxidants in their diet, although specific antioxidant supplementation can be useful for aging stallions (where a natural decline in fertility may be an issue), busy stallions (including dual-hemisphere stallions) and young or immature stallions. Antioxidants are also very important for stallions whose semen is intended for AI use, as cooling and/or freezing can lower viability and progressive motility. It’s also important to bear in mind that competing stallions used for semen collection often also remain in full exercise during the breeding season so may benefit from increased levels of dietary antioxidants.


As horses age, so do their bodies and vital organs, resulting in a reduction of organ and metabolic function. Consequently, susceptibility to oxidative stress is increased. Senior horses, particularly if they are still in work, may benefit from additional antioxidant support. In most cases, a suitable hard feed will provide sufficient levels, although, geriatric horses with specific concerns e.g. Cushing’s syndrome, may require additional supplementation.

Exercising Horses

Exercise increases the production of free radicals in the body. Horses that are involved in very high intensity exercise; endurance type activities, traveling long distances or competing in several shows, races, or events in a short period are more prone to deficiencies in antioxidant status. Optimal antioxidant supplementation may help these horses to perform to the best of their ability, recover faster and train more effectively.


Horses suffering from illness or disease are obviously at increased risk of oxidative stress. Although free radicals are vital for immune function, excessive amounts can be harmful. Several clinical problems including degenerative bone and joint diseases, laminitis and equine motor neuron disease (EMND) have been associated with surplus free radical production and, or potentially as a consequence, low antioxidant status. If your horse is ill or injured contact our nutritional team, who will work with you to put together a bespoke nutritional plan specifically tailored to your horse’s individual needs.

Horses suffering from asthma or other respiratory concerns

Equine asthma is a relatively new term for a well-known problems involving inflammation of the respiratory system. Previously these disorders were known as Inflammatory Airway Disease (IAD) and Chronic Obstructive Pulmonary Disease (COPD), Recurrent Airway Obstruction (RAO), Broken wind or Heaves. Studies have shown that horses suffering from respiratory conditions can have lower levels of antioxidants in their lungs. Therefore, specific supplementation with antioxidant such as vitamin C can be beneficial.


Horses and ponies suffering from chronic laminitis are often maintained on restricted grazing which will limit their antioxidant intake. Studies have shown that chronic laminitis results in significantly higher levels or free radicals, even when free from signs of the disease. It is therefore advisable to include a supplementary source of antioxidants (e.g. a nutrient-rich balancer or multi-vitamin and mineral supplement).

Antioxidants in Connolly’s RED MILLS feeds

All Connolly’s Red Mills feeds contain our unique Pro Balance vitamin and mineral package which includes a blend of key antioxidants including Vitamin E and selenium. Other key trace elements (e.g. copper and zinc), which play a role in the horse’s total antioxidant capacity, are also included in all Connolly’s RED MILLS feeds.

Our expert nutritionists have also specifically formulated our Care range for horses needing elevated levels of antioxidant support (e.g. horses prone to tying up). All the feeds in our Care range contain a blend of antioxidants including elevated levels of vitamin E, organic selenium and Vitamin C.

Antioxidant Supplements

In certain situations, specific antioxidant supplement can be enormously beneficial. Our supplement partners Foran Equine have a range of options:

  • FOR-RECOVERY & FOR-REPRO: Scientifically developed Ubiquinol CoQ10 supplements. Designed for horses that are at risk of high levels of oxidative stress, such as performance horses, racehorses and breeding stallions.
  • V.S.L Powder & Liquid: A powerful antioxidant supplement providing Vitamin E, Selenium and Lysine. Ideal for competition horses, horses prone to tying up and broodmares during late pregnancy and early lactation.
  • Vitamin E Supplement: A powdered natural Vitamin E supplement. Suitable for all horses including those at risk of, or suffering from, clinical problems such as protozoal myeloencephalitis (EPM), equine degenerative myelonencephalopathy (EDM) and equine motor neuron disease (EMND).
  • Zosfor: A powdered supplement containing natural super-antioxidant bioflavonoid hesperidin, vitamin C and K to help support the capillary health and respiratory function.

The most appropriate supplement will depend on your horse’s individual needs so please Get in Touch with our Nutritional Team  for bespoke advice.

The Bottom Line

Free radicals, if present in excess, can damage vital organs and tissues. Although horses have internal mechanisms to control the levels of free radicals, factors such as exercise, pregnancy or illness result in increased free radical production. By feeding Connolly’s RED MILLS your horse will receive a blend of dietary antioxidants to help keep them healthy. Should your horse need additional antioxidant support Foran Equine offers a comprehensive range of antioxidant supplements to suit all horse and ponies.

If you’ve got a question about feeding your mare, get in touch with our expert team.

Ask Our Experts


Contact our sales team via WhatsApp or email