Field Trial Reports

Participant horses have included Thoroughbreds, Warmbloods, Standardbreds, Arabs and crossbred horses.

The results of these trials have been collected via trainer and rider questionnaires and by blood testing. Blood testing measured the response to the organic amino acid chelated selenium in Sel-Plus.

Sel-Plus has undergone extensive trials in New Zealand, Australia and Asia. It is currently being used in many countries.



The overall responses were assessed through trainer and rider observations. Blood testing for whole blood selenium is no longer considered an adequate measure of the animals biologically available levels. Testing for the selenium dependent enzyme, glutathione peroxidase (GSH-Px) is the method of choice. Each molecule of this enzyme contains 4 atoms of selenium, and is involved in immune, skin, fertility, muscle, hormone and many other essential systems in the equine.

Therefore, if the horse has adequate levels of selenium, he should produce sufficient GSH-Px, and by measuring it, we can tell if the horse is utilising selenium effectively. By contrast, whole blood selenium (WBS) does not give as accurate an indication of the biologically active selenium levels. The blood system acts as both a nutrient supply and waste disposal system, so it is impossible to differentiate with this test alone if the selenium is being utilised or disposed.




Both parameters were measured during this trial before and after three months daily supplementation with 15 grams of Sel-Plus providing 1mg elemental selenium as an organic selenium amino acid chelate.

The trial consisted of 25 horses under different management systems and all horses in work. Twenty two horses ( A – V ) were given Sel-Plus, three ( W,X and Y) were not and acted as controls. Horses A – V were all receiving selenium in inorganic form (sodium selenate) prior to the trial excepting for horses L and M. Control horses ( W,X and Y) continued to receive inorganic selenium supplements throughout the trial period.



Eighteen of the twenty two trial horses (82% ) showed a positive increase in GSH-Px.

One horse ( Q ) showed no change, two horses ( H,J ) showed slight decreases and one ( G ) showed a statistically significant decrease. This horse G was receiving large amounts of oil (fat) in his diet. Controls W and X showed a decrease in GSH-Px and Y no change.

Sixteen of the twenty two horses ( 73% )showed significant positive increases in WBS levels. Two horses ( 9% ) showed very slight increases. One ( 4.5% ) showed slight decrease and 3 ( 14% ) significant decrease. The controls WBS generally remained the same or tended to increase.



The most significant finding of this trial was that feeding organic selenium from Sel-Plus produced an increase in GSH-Px levels in 82% of horses. An corresponding increase in WBS occurred in 83% of the 18 horses, a decrease in 17%. The decrease in WBS may be due to the horses ability to utilise the organic selenium more efficiently than inorganic.

Horse G is a very thin working Thoroughbred being fed up to 250 grams of fat in the diet daily. Feeding of fat is thought to increase the horses demand for anti-oxidants such as Vitamin E and selenium and this excessive demand may be reflected in the depletion of GSH-Px levels. This horses WBS levels marginally increased.

Questionnaire responses from the trainers of these 22 horses all 100% indicated positive improvement in the horses.


Forty horse owners were surveyed as to their horse’s responses to daily supplementation with Sel-Plus. The horses had been receiving Sel-Plus for a minimum of three weeks and others for several months. The responses were first categorised as positive or negative.

  • Positive changes seen 90%
  • Negative changes seen 0%
  • No changes observed 10%

We asked for comments on the type of changes seen and these were remarkably similar

  • Improved working temperament and relaxation
  • Improved condition, hair-coat and muscle mass
  • Improved suppleness and freedom of movement
  • Improved energy and performance