Friday, August 5, 2016

Analyzing Nimo's Diet: Introduction

I've been meaning to do a series of posts analyzing Nimo's diet and discussing nutrition, but every time I tried to write the posts, I realized that it is a very complicated subject, and I doubted that I could even begin to do it justice.  However, I really need to do an analysis of what Nimo is eating.  I think it is particularly important for performance horses to have not just good, but excellent, nutrition, but I've also come to the conclusion that even pasture buddies need to have owners who pay attention to what they eat.  Equine nutrition is no longer as simple as "throw the horse out in the pasture and if his weight looks good, everything must be fine."   I've been experimenting with a lot of different types of feeds and supplements, and I feel like I'm starting to narrow down what I think is working, at least for now.  But I also have a couple of concerns that I'd like to examine more closely and scientifically.  So the next step is to figure out if what I think is going on is related to reality or just made up in my head.  You get to follow along with me while I work through the process!:)

The first step is consulting Nutrient Requirements of Horses: Sixth Revised Edition to find out what the basic nutrition requirements are specifically for Nimo.  If you have never read this book and you have a horse, my strong advice is to read it.  It is the source for almost every other equine nutrition book out there (at least the ones for lay people), and it has 341 pages of information on pretty much everything to do with feeding your horse.  If the price tag is too much for you, you can read it online for free here:  http://www.nap.edu/read/11653/chapter/1.  I also find the information published by Kentucky Equine Research (KER) to be helpful and sometimes more up-to-date than what is in Nutrient Requirements (which was published in 2007).  KER does manufacture and sell feed and supplements, so I'm not sure the research could be considered truly independent, but it seems legitimate to me and the company seems to be well-respected for its feed formulations here in Virginia.  KER's published research can be viewed here:  https://ker.com/published/.  And a lot of universities with strong agriculture programs will publish staff papers online, often through their extension programs, so that can be another good source of information.  Plus, there are the veterinary journals, but I haven't had the time or money to do a lot of searching in those as of yet.

For the purposes of this series of posts, I will be relying heavily on Nutrient Requirements, although I will try to add in other sources as well.  I hope to provide enough information so you can follow along with me, if you like.  (Or even better, double-check my work to make sure I haven't made a mistake!)

To start off, I need to make some determinations about things like Nimo's weight, his work level, and the total volume of food that he eats.  The reason is because the way nutrient requirements are determined is through formulas that typically involve one or more of those parameters.  I'm definitely going to be estimating all three numbers and obviously if my estimates are significantly off, it will affect the accuracy of the results.  (Problem number 1 with trying to figure out what to feed your horse!)

Nimo's Weight
Ideally I would drive Nimo to one of the area equine hospitals and ask if I could borrow a scale.  (Note that I have seen "horse-size" scales at some endurance rides, but surprise, surprise, they look much too small to accommodate Nimo's not insubstantial size!)  However, most people don't have access to a scale, so I opted to try one of the weight calculators available.  There are some formulas out there, too, but for the sake of brevity, I used this online calculator:  http://www.thehorse.com/articles/31852/adult-horse-weight-calculator.  Two measurements are needed to use the calculator:  the circumference of the girth area (as measured just behind the point of elbow and over the withers about one inch from their highest point) and the length of the horse from the point of shoulder to the point of buttocks.  The website has a short video to walk you through the measuring process, but I can see some room for error, which could definitely affect the results.  When I plugged Nimo's numbers (82" girth and 71" length) into the online calculator, I got 1447 lbs.  The calculator does note that it may not be as accurate for tall horses (is 17 hands tall?) and larger-boned horses, though, so I decided to bump the number up to an even 1500 lbs, or 680 kg (because all of the nutrient requirement formulas use weight in kg).


Work Level
Nutrient Requirements describes several work categories on p. 26 in Table 1-10, and I decided that Very Heavy is probably the best fit for Nimo based on the descriptions.  The Very Heavy category includes work that involves a mean heart rate of 110-150 bpm along with 6-12 hours a week of work.  Nimo is not always working that much, but right now, I'm riding 5-6 days a week with 4-5 days at 1-1.5 hours and 1 day at 2-3 hours.  The work involves dressage schooling during the week with a little hacking around the farm and endurance conditioning, including a lot of trotting and climbing, on the weekend.  The heat and humidity also add to the intensity of the work.

Weight of Food
Some of the formulas used in Nutrient Requirements use the total amount fed to the horse each day in terms of kg of dry matter (DM).  What that means is you can't just weigh the amount of food you feed; instead, you have to weigh the food (or estimate consumption for things like hay and pasture) and then convert that weight into dry matter.  Dry matter is basically the weight of the food after all moisture has been removed.  It allows all types of feeds to be compared equally, but it can be a bit tricky to calculate.

To come up with a reasonable estimate, the first thing I did was weigh the amount of concentrated food that Nimo gets each day.  (Note that while he does get a few supplements, the amounts are quite small and it didn't seem worth it to include them in this process.)  He gets:

Beet Pulp: 2.25 lbs
Oats: 3.5 lbs
Triple Crown Growth (textured feed): 4.125 lbs
Total concentrates =  9.875 lbs

Then I assumed that Nimo is eating about 2% of his body weight each day (typically horses eat between 1.5 and 3%), which is 30 lbs.  I subtracted the total concentrates from that amount to get 20.125 lbs.  From there, I decided to split that amount into hay and grass because Nimo spends about half his time in his stall eating hay and about half his time out in the pasture eating grass.  To make things slightly easier, I decided to use 10 lbs for hay and 10.125 pounds for grass.

So here's where we are in terms of total amount of food eaten each day:

Beet Pulp: 2.25 lbs
Oats: 3.5 lbs
TC Growth: 4.125 lbs
Hay: 10 lbs
Grass: 10.125 lbs

Now we have to convert all of those amounts to dry matter.  I found a couple of sources to help me estimate the dry matter of each type of food because I didn't want to spend my time using one of the assorted methods out there to actually evaporate the water myself.  If you are so inclined, though, check out this article for how to do it:  http://extension.uga.edu/publications/detail.cfm?number=SB58

For beet pulp, I found this article that describes how beet pulp is made and it states that the shreds are dried to 10% moisture, which means beet pulp is 90% dry matter.  So 2.25 x .90 = 2.025 lbs.

For oats, I found this article that lists oats as 90% dry matter (along with some other grains, if you happen to feed something other than oats).  So 3.5 x .90 = 3.15 lbs.

For TC Growth, I couldn't get any number off the feed bag or the Triple Crown website, but I did find this article that mentioned wet corn has a DM value of 74%.  I'm not really sure if wet corn and textured feed are quite the same in moisture content, but it seemed like a reasonable starting point. So 4.125 x .74 = 3.0525 lbs.

For the hay, I found this article that said hay is typically about 90% dry matter.  So 10 x .90 = 9 lbs.

And finally for the grass, I used the same article as for the hay.  The article stated that grass is typically 20% dry matter, so 10.125 x .20 = 2.025 lbs.

Now, I need to add up all of the DM values and convert the total to kg:

DM (kg) = 2.025 + 3.15 + 3.0525 + 9 + 2.025 = 19.2525 lbs x .45359237 = 8.73 kg

And finally, I have the three numbers that I need for calculating nutrient requirements!

Nimo's weight = 680 kg
Nimo's work level - Very Heavy
Nimo's food on a DM basis = 8.73 kg

That's it for today, but my next post will discuss energy requirements.  And if you notice any errors in my calculations or process, please let me know:)

1 comment:

  1. This information and these resources are so timely for me right now! Thanks for compiling it!

    ReplyDelete