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Horse Health

Can feeding improve the quality of horse’s hooves?

Dr Teresa Hollands, BSc (Hons), MSc (nutrition), PhD, R.Nutr, Technical Manager for Dodson & Horrell Ltd has studied the relationships between nutrition and hoof quality as part of her PhD studies, whilst the relationship is far from straightforward, Teresa shares some of her thoughts on the conundrum.

 

‘The horse’s hoof has been a subject of deep study for centuries and I know of no mechanical contrivance for which the mind of man can contemplate with greater wonder and admiration. What is the use of a horse, however good or well fashioned, if it has not a sound foot to stand upon?’ Duncan (1935)

There is no simple answer to this question, but there are two issues that you have to think about before you can even start to study the relationships.

1. Firstly, can nutrition really affect the hoof tissue independently of the horse’s skin and hair because hoof horn, skin and hair are biochemically very similar.

2. Secondly what do we mean by quality and can quality been seen by the naked eye. Because if quality cannot be seen or measured, how do you know if it has improved or got worse?

Diet

If there was a straightforward relationship between nutrition and hoof quality, then it would be very easy to adjust diets and see a result. However if you took 10 or even 100 horses or humans and fed them the same diet, it is highly probable that some will have gleaming skin and hair but others will have dull hair or coats. Some horses will have uncracked hooves, some people will have brittle nails and others will have lovely long nails, (assuming they are not horse owners!)

There are specific nutrients which are more intimately involved with the development of tissues containing the protein keratin, but remember that hair, skin, nails and hoof horn are all made up of tissues which contain keratin, so the hoof is not an isolated case from a nutritional point of view.

What is the relationship between the hoof and other epidermal tissues?

The outer covering of the vertebrate body consists of two layers the dermis and the epidermis. The epidermis consists of layers of cells which contain a fibrous proteinaceous material classified as keratin. The epidermis is formed by keratinisation, which is the process by which living epidermal cells differentiate into dead corneocytes in order to fulfil a variety of roles.

The main function of the epidermis is a barrier between the insides of the animal and its environment; for example keratinised structures retain body fluids, act as a barrier to external fluids, prevent invasion by micro organisms, bacteria and other foreign matter, protect against mechanical injury, and are used in food gathering, temperature regulation and locomotion

In the horse, the epidermis has been modified in places to provide specialised epidermal appendages, ie the hoof capsule. The hoof capsule has two main functions; the protection of the sensitive living tissues from mechanical, physical and chemical damage and the transfer of forces from the skeleton via the limb to the ground whilst the foot is at rest or in locomotion.

 

Trace elements which are specifically involved in keratinisation

At the biochemical level imbalances of the trace elements, calcium, copper and zinc, have been shown to affect keratinisation. Copper deficiency reduces the cross-linking between high sulphur proteins; the removal of calcium from cultured skin keratinocytes prevents differentiation into corneocytes and diets deficient in zinc result in a reduction in keratin production. Keratinised tissues with different functions contain similar keratin proteins, and therefore trace element deficiencies have similar effects on the pattern of keratinocyte differentiation across tissue types such as skin, hair, fingernails and indeed hoof. In fact altering the amounts of zinc, copper or calcium has been shown to have direct effects on keratinisation, by changing the gross appearance of the tissue or changing its mechanical properties which in turn has direct or indirect consequences on the function of the tissue.

 

Measuring quality

If there is a link between nutrition and the function of the hoof, then it is important that the function and any interactions between mechanical properties, visual appearance and the affects of nutrition can be measured accurately in order to measure the factors affecting hoof wall integrity. After all what do you mean by hardness and indeed do we want a hoof to be hard? Many researchers have measured the hardness of a hoof and tried to relate it to the amount of zinc or copper in the hoof clipping. But hardness is simply a measure of how far an indenter goes into the hoof wall……does this mean anything when related to how the hoof works?
Perhaps a better measurement would be the strength or brittleness of a hoof. But where do you take those measurements? If you take a physical measurement from say half way down the hoof and then take a hoof clipping to analyse for trace elements, you are likely to be comparing material that might be formed over a 3 month period. What happens if the first measurement you take is on hoof horn which was formed in the winter and the second from hoof horn which was formed in the spring? Nutrient intake would be completely different when the keratinisation was taking place, the older horn will have undergone more loading cycles and more wetting and drying, so is it fair to take a mechanical measurement and a trace element analysis and try and relate the difference in trace elements to the difference in mechanical properties; I don’t think so, but that is what many people have done in the past.

One of the biggest differences between our horse’s hooves and their skin or hair is that the hoof wall epidermis has to sustain the bodyweight of the horse without failing. A mechanical engineer will tell you that the ability of a structure to bear load is dependant upon the material from which it is made, its size and its geometric shape, If a certain shape of hoof results in increased stress concentrations at specific anatomical positions, due to geometric irregularities, this area of the wall maybe predisposed to cracks, irrespective of any nutritional influences. So there are many things which need measuring before you start to investigate any true relationship between nutrition and hoof quality.

It is true that overt deficiency of say zinc can be measured and seen in epidermal tissues, however the signs are much more apparent in hair compared to hoof and it is highly unlikely that horses and ponies suffer deficiency diseases in the 21st century; rather they suffer from diseases of excess.

So maybe the reason the horse gets cracked hooves is because he is carrying too much weight on his feet and the volume of hoof material is not sufficient to take his excess weight. In order to ensure that the hoof does not splinter into lots of little bits or fail completely, the hoof material cracks so the hoof can continue to function as an absorber of energy. A little like the crack in the plaster of your house, it is only of significance if that crack affects the wall of your house and causes the wall to collapse!!

Also consider that if the relationship between nutrition and quality was straight forward then the TB race horses in Newmarket would have the best feet on the planet and the wild horses of the world would have the worse feet. Depending upon what you define as best or worse of course…..however it is well accepted that TBs have ‘bad’ feet.

Perhaps it is case of genetics? With the human genome now completed, other species are not far behind. Research has suggested that the presence or absence or mutation of certain keratin genes might be reflected in the function of the epidermal tissue. During the early stages of hair development, a specific keratin known as K17 is present in nearly all primary hair cells. As the hair tissue matures further, K17 protein is maintained in the outer root sheath and the matrix of the bulb. Research has shown that the absence of K17 is related to the acute fragility of the first hair shaft. It would be interesting to speculate that hoof horn described as poor quality may have different keratins compared to horn of good quality.

Thus whilst we know that horses have specific requirements for individual minerals and vitamins, it is highly unlikely that any vitamin or mineral can have the Heineken effect on the hoof, i.e. target the hoof and no other parts!!! Also it is very apparent that any relationship if it does exist is not straightforward.

Horses fed predominantly hay will be deficient in some minerals, most vitamins and quality protein, all of which are needed for renewal of all tissues, thus poor foot condition and poor coat maybe the first clinical signs of this unbalanced diet. Before looking for magic ingredients, check that the horse’s diet is balanced. If correcting for those imbalances does not have the effect you had hoped for only then might be appropriate to look at individual nutrients.