tree chewing

Question
I have two TWH horses in about 2AC. no grass ,They have a roll of hay at all times they have a mineral block I feed them morning and night sweet feed but they are chewing the bark off the trees .I am not worried about the trees but will it bother the horses?

Answer
Hi John,

Thank you for your question.  It is sometimes hard to tell if horses chew wood due to some sort of nutritional deficiency or if it is just habit.  Sometimes it starts as a deficiency and may remain as a habit even though the deficiency has been remedied.  Sometimes it's a habit developed out of boredom.

Nutritionally wood chewing, be it the boards of a stall or the closest tree, could indicate a deficiency in effective fiber (not enough to chew) or a deficiency in phosphorous. You have indicated that your horses have access to free choice hay so a lack of effective fiber is clearly not the cause.  You do have a mineral block available to the horses which may contain phosphorous, but sometimes horses will not get enough mineral from licking the block.  In this case, feeding a pelleted mineral will ensure sufficient consumption of mineral...a calculated balanced ration will let you know if this is the case.  The fact that your horses are limited to a small paddock and eat standing in one place may deprive your horses of normal foraging behavior leading to boredom, which could account for the chewing.

There is some speculation that the habit can be dangerous in that the slivers of wood that they are consuming may lead to the development of colic...but for me, this is more of a worst case scenario and normally not of grave concern.  There are a long list of trees and plants that are poisonous to horses, and this is something that you may want to seriously look into.  Reactions to poisonous plants/trees can be severe and potentially deadly.  One great resource describing poisonous materials is:  http://en.wikipedia.org/wiki/List_of_plants_poisonous_to_equines  You will want to ensure that the trees in your paddock are not on this list, or take the necessary action to remove them if they are.

Of course, the final danger is to the trees...as horses can quickly chew all of the bark off the trunk and kill the tree.

Thanks, Corlena