Revisiting 25,000 chews per day

Last February I drove the back roads of Tennessee from 7 am until 7 pm traveling to 5 different farms all with horses with sharp teeth waiting for their routine floating.  In the hours that passed between farms I was struck with how rural some parts of this country could be.  During the day of traveling, I passed only 2 gas stations and convenient stores.  That is unheard of in all the places I travel.  Yet for bathroom breaks, it can also become a disaster.  Out of necessity, I entered the first store of the two I would see this day.  It was a small place not associated with a national chain.  As I opened the front door, my lungs were filled with the best fried chicken smell and, as it turned out a short time later, the best tasting fried chicken I have ever eaten in my life.

I sat in my truck’s cab with the winter sun warming the interior as I delighted in the delicious find I had just made.  By accident and by luck, I had found a very small piece of the fabric of life in rural America that gets people out and moving on a cold winter’s day.  My mind began to think of similar times when luck brought me in front of something special, and for some reason it drifted to a small article about horses I had accidentally found.

A while ago I came across a small study done by Katherine Houpt, VMD who is a professor emeritus at Cornell University Veterinary school that discussed how many times a horse chews in a day.  It caught my eye for two reasons.  First, I personally know Dr Houpt because I had worked for her as a student when I was at that vet school.   Second, I wanted to know everything about horse teeth and I thought this would be interesting.

In life, it is the little things we often overlook that seem to tell a big story.  One of Dr Houpt’s specialities was to study those little things in an effort to explain the big story of why horses do what they do.  For example, in the early 1980’s as a vet student, I accepted a job with her that had me stay up throughout the night and every hour, I went to several stalls and counted how many foals were awake and nursing their mothers.  We had no stall cameras back then, only hungry students trying to get money to put food on the table.

It was this kind of work Dr Houpt did observing the mundane counting of things about horses that people would take for granted.  She then studied the data and presented it for fellow researchers and veterinarians to use.  It was easy for me to visualize hungry students with old fashioned hand counters pressing their thumbs down on the lever that advanced the mechanical digital counter every time a horse opened and closed their jaw.

In the paper I had found by her, Dr Houpt’s data said that a horse would chew about 10,000 a day if it was in a stall most of its life while a horse out on pasture would chew about 40,000 times a day.  She also made an observation (no proof or conclusions) that she only saw cribbing horses in the 10,000 chews per day group of horses.  She left us the data for us to use, but as I chewed slowly the tender and succulent chicken and my mouth opened and closed, I revisited the 25,000 chews per day I have often told horse owners that an average horse chews per day.

Was it possible for a horse to chew that many times?

I first made an assumption that a horse chew lasted about 1 second per chew.  I think it is a little slow but for convenience, it was good enough.  Then I determined that there are 86,400 seconds in a day (60 x 60 x 24).  To get the average number of chews, I added 10,000 and 40,000 and divided by 2 = 25,000.  Dividing 25,000 by 86,400 gave me about 29% of the day is spent by the horse chewing.  My conclusion was that it was possible.

My chicken was almost gone and I toyed with the thought of going back in for more, or possibly never leaving this town, buying a farm here and having this chicken for lunch every day for the rest of my life.  That was quickly replaced with more math.

How many times does a horse chew in 30 days?  750,000 times.  How about 6 months?  4.5 million chews.  A year?  9 million chews.  And all of this was using the average of 25,000 chews per day.  What about the 40,000 chews on the high end of the horse turned out around the clock?  That horse chews about 46% of the day which again is certainly possible.  My calculations determined that these horses chew 1.2 million chews in a month, 7.2 million chews in 6 months, and a whopping 14.4 million chews per year.

Licking my fingers clean of every drop of chicken fat, I came to realize why horses have teeth that continually erupt throughout life with reserve tooth.  It is an absolutely genius mechanism for an animal that constantly is chewing.  It further explains why horses that are turned out all the time develop sharper edges which counters the often proposed explanation that grass has “natural silicates” that causes the higher ware rate.  No, it is because they chew more.

It also answers the observation I have that horses on a liquid diet or on a limited feed intake often only need their teeth floated once a year.  They chew less as they slurp their feed like a giant smoothie through a straw.  This all makes so much sense.  I also became amazed on the amount of movement in the TMJ’s (the joints of the jaw) and how it is a perfect joint able to withstand 14 million chews times 25 years without ever causing a horse to stop chewing.

I went back in to wash my hands and faced the reality that my new found fried chicken heaven would soon be a memory.  I also pondered the fact my own dentist had told me that humans chew about 2000 times a day.  We chew less in a year than a horse does in a month.  Wow!  No wonder I drive down the back country roads of states all over this country and file smooth the pain causing sharp points of horses every month of the year.  If they ever stop chewing, I will be out of a job.

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