Does Zinc Really Help With Foot Problems?

In an article last year I mentioned that one benefit from supplementing with zinc, particularly in the form of the amino acid complex, can be an improvement in hoof hardness and a subsequent reduction in lameness problems.

Given that New Zealand soils are not considered to be deficient in zinc and that many herds receive high levels of zinc supplementation during the facial eczema season, the validity of supplementing with zinc to improve hoof health has been questioned. Quite rightly, a reader has asked on what basis the low daily level of zinc amino acid complex recommended could be expected to help with hoof condition under New Zealand conditions.

As I pointed out in the previous article, the trial evidence that supports this benefit comes largely from trials conducted in other countries with high producing herds, particular in North and South America. A long-term controlled study evaluating zinc supplementation and hoof health in dairy cattle has not yet been conducted in NZ.

However, there have been a considerable number of anecdotal reports by NZ farmers who have perceived a reduction in foot problems following the use of zinc supplementation for a year or so. As well, a number of farmers have contacted me with the observation that after using zinc amino acid for a year or two but then ceasing, they have noticed an increased incidence of lame cows.

Of course, anecdotal reports are no substitute for controlled scientific studies, but they can stimulate one to theorise why a positive effect might be occurring if the observations are in fact real.

Firstly one must consider the situation in the herds subjected to well controlled trials. None of the herds in the studies were on zinc deficient soils or diets, so in this respect, they can be said to have been in a similar situation to NZ herds. In these studies, as well as monitoring the incidence and type of lameness over the two year periods, the changes in hardness or texture of the hooves were measured. The incidence of lameness was significantly less and hooves were significantly harder in the zinc supplemented herds, compared to non-supplemented controls

So how might this have occurred? We know that zinc as the amino acid complex is absorbed more efficiently than inorganic forms. From other studies, it appears also that this form of zinc is used and metabolised more effectively by the body. Zinc is consistently required by enzymes that synthesise and maintain the integrity of keratin, the main constituent of hooves. So maybe the form of zinc influences how effectively it is incorporated into the matrix of the hooves and may be why the hoof strengthening effect has been seen consistently with zinc amino acid but not inorganic zinc salts.

Another reason why regular zinc supplementation may help hoof health relates to the fact that zinc is required by over 270 enzyme systems in the body. Clearly, it is a mineral in much demand. But unlike many other minerals, there is no real storage organ for zinc. The only reserves may be in the keratinous tissues like skin and hooves. So if another body system has an urgent demand for zinc, (such as the immune system when an infection occurs), then zinc may be preferentially directed to organs other than the skin or hooves. Regular supplementation with a readily bioavailable source of zinc may balance the fluctuating demands of different organs and maintain an optimal level that is good for maintaining hoof integrity.

There is still much to learn about the role and requirements of zinc in the body. What constitutes an optimal daily intake of zinc as opposed to what is required to prevent symptoms of a known deficiency, could be quite different. That supplemental zinc in readily bioavailable forms provides benefit to dairy cattle has been shown consistently in many countries. In New Zealand, where cows are frequently stressed, nutritionally and otherwise, zinc requirements may be higher than previously believed, especially if hoof strength and health integrity is to be maintained as well as all the body’s other requirements for zinc.

So ultimately, a regular and consistent intake of bioavailable zinc does seem to make sense for keeping hooves supplied with sufficient tomaintain hardness and good health.