Q: I own a five-year-old 15.2hh cob mare who is currently in light work and competes occasionally at the weekends. She is kept at grass and is fed 1⁄2lb of pasture mix and has access to a salt lick. She has recently begun chewing the bark of a sycamore tree in her field. Although I have tried covering the base (the part she’s chewing) with mustard, waste oil and hoof oil, she still insists. I have never encountered this problem before and need some advice.
Nutritionist Kate Jones replies: Chewing trees and licking soil is a common problem in horses at grass and it usually relates to a diet deficiency. Modern pasture is limited as it normally only contains one or two species of grass and perhaps a legume, such as clover. Compare this with the hundreds of species of grasses, legumes, herbs, shrubs and trees in the wild and you see how deficiencies can come about.
Additionally, in certain areas of the country, a nutrient deficiency occurs in the soil, which is in turn passed to the grazing and local hay. Your horse’s problem will be compounded by low levels of hard feed, which provide important vitamins and minerals for those on a high-concentrate diet.
To combat these contributing factors, I recommend you introduce a general-purpose supplement to the feed daily, to supply whatever missing goodness your mare is seeking from the tree bark.
Unfortunately, once habits like these are in place, they are often hard to break. You may find it necessary to fence off that particular tree until she has learned that she is getting all she needs in her bucket.