We also learn something new every day! It is always thought that horses are comparable to humans in many things, including when it comes to the production of vitamin D. We also thought this and also that horses that are in a fly rug / eczema rug all summer, for example, that they can get adeficiency of vitamin D. There was also little scientific study on this, so the assumption was quickly made that this is comparable to humans. But now an investigation has been done!
What is vitamin D important for?
Vitamin D comes in 2 forms: D2 and D3. Horses get vitamin D2 from food (grass, hay and, for example, herbs), vitamin D3 is produced by the horse itself. Vitamin D plays an important role in many processes. For example, it is involved in:
– The absorption of calcium and phosphorus
– The support of the immune system
– Preventing unintended cell divisions and cell mutations.
– The regulation of the production of keratin in the skin
– Different neurological functions
The sun may have little effect on vitamin D production
Various studies/opinions assumed that the production of vitamin D in horses is comparable to human production. That horses therefore need UV light for the production of vitamin D3. A number of studies had already been done that showed no clear differences between horses with blankets and horses without blankets, but no firm conclusions were ever made. A recent study looked at whether sunlight actually has an effect and whether it is necessary to supplement vitamin D3. Firstly, this study showed that horses have much lower values than humans. In humans, a value below 25 nmol/L is considered a deficiency, while the study showed that the horses had an average value of 10.7 nmol/L.
The study also showed that the horses that were kept outside on the grass all year round had unmeasurable levels of vitamin D3, even in the summer period with a lot of sunshine. These horses did have higher vitamin D2 values than horses that were kept in the stable. It was also striking that these values were higher in summer than in winter.
Is it necessary to give vitamin D to horses?
The studies concluded that horses are actually quite capable of extracting vitamin D from roughage. Horses standing on the grass in particular do not need extra vitamin D. The values that horses need per day are also many times lower than human values, so a horse only needs little vitamin D per day. And which form a horse receives (D2 or D3) makes little difference to a horse.
Additional research is needed!
These data are based on a recent study in horses and already provide a lot of information. Of course, more studies will have to follow in order to draw a real, clear conclusion. Because what about horses that don’t get on the grass and are fully covered in a paddock and get poor hay? For the majority of horses, it is not necessary to supplement with vitamin D, as long as they receive the correct nutrition. We therefore always recommend adding a quality balancer so that your horse always receives a base of vitamins and minerals.