Sunday, December 7, 2008

Nutritional Management ; Algebra 101

I mentioned in an earlier post that I was spending some time researching feed values. Well, I never imagined I would get this waist deep in the research. This weekend, my kitchen table and desk were covered in articles, downloaded material, charts, graphs, notes and formulas. Tom thinks I have stepped off the deep end for sure this time and I would probably have to agree. In fact I can’t remember that last time I had to do so much algebra and actually enjoyed it. The fact is that once you start looking, one thing leads to another that leads to another. It required quite a bit of information gathering on my part before I found what I was looking for. Then, the process of weeding out what you need and don’t need before you can even begin to try to make sense for your unique horse and situation. Since I make my living analyzing data, I was in all my glory and analyze I did.

My goal is to calculate out JB’s ration with respect to Degestible energy, crude protein, etc in order to best determine if he is getting what he needs for his work load. To begin, I had to figure out two things at least to start as a baseline:

1. How much feed is JB currently getting? ( Hay and Concentrate)
2. How much should he be getting?
The “How much “part is actually broken into two parts. The % of his body weight he receives in forage and concentrate and the actual Nutrient Requirements.

I knew a couple of things already that I would keep in mind as I go through this process.

JB weighs approx 850 lbs give or take. A horse that weight with moderate work (1-3 hrs of riding time per day) should be in the ball park of 20, 400 calories per day or for heavy work (4-5 hrs of riding time) 27,200 calories. Of course those numbers can fluctuate with the difficulty of work. If I rode JB for 2 hrs every day with most of the work out consisting of hills, he will obviously burn more than the average of 27,200 calories on a daily basis. It’s best to just use these as a ball park and let common sense lead from there.

Right now, we feed round bales and fork off feed morning and night for all the horses. Most of our horses are easy keepers. I first had to figure out how many pounds of hay each horse was receiving.

I know that on average the round bales are about 1200lbs and that one round bale lasts us 11 days worth of feeding. I feed 5 head of horses off that bale for 11 days.

1200 divided by 11= 109lbs of hay is fed out per day (am/pm)

I take 109 lbs divided by the 5 (horses)= 21.8 or lets round to 22 lbs . 22lbs is fed to each horse every day. That works out to be approx 11 lbs am and 11 lbs p.m. Now keeping in mind that the 4 geldings are fed out together and the amount of hay per horse may vary because it depends on herd rank. I know for a fact Roman and Rebel are getting more than Cassidy. As long as everyone is maintaining weight I don’t worry too much about it.

So I have #1 solved for with Hay. In addition I feed him 2.4 lbs of grain per day

Moving on to #2. I want to figure out what JB should be at. I started by calculating what % of body weight his feed is. For forage the average horse at moderate work should be between 1.0-2.0 % of its body weight.

22lbs works out to be 2.59% of 850 lbs. JB is receiving, if rounding, 2.6% of his weight (850lbs) in forage. That is a little over the recommended amounts noted above but I am not concerned because he doesn’t always clean all of it up . This number probably does fluctuate up a bit more in the summer as he spends 50-60% of his time grazing in a pasture as well. I would rather he receive more forage than concentrate anyways and as long as his condition is staying good, I am not concerned about his receiving too much forage. If I can have him in an eating situation as close as he can be to what he would do in the wild, the better off I am . Since he has a lot of area to move, he is expeding more energy as rest as well as during the time he is being ridden. It’s at this point that I feel that the formulas and numbers have to go a bit to the side and common sense has to play a role. If he’s gaining weight obviously it would tell me he is getting too much and I would cut back.

I did this same calculation for the grain as well. It is recommeneded that horses in moderate work levels be between .75-1.5% of their body weight in grain. I currently feed JB Running Horse Cut & Slide. It’s an extruded cereal grain with a beet pulp base. During the peak of his conditioning schedule this summer , he was receiving 2.4 lbs of grain per day. His work schedule was moderate to heavy.

2.4 lbs is approx .28 % of 850 lbs.

So- Final numbers reveal that his total % of forage and concentrate combined are 2.87%

Total combined intake of forage and concentrate should be in the range of 1.75-2.5 % of horses body weight. JB appears to be a bit over the recommended amount but again, JB appears to be in good flesh. It is possible that he weights more than 850 lbs as I only have a weight tape. It is probably off a bit.

This initial analysis has provided me with a baseline and a little insight as to what kind of keeper JB is. When I look at those percentages, I would expect that he would actually be a bit heavier than what he is currently maintaining. While he isn’t thin, he could stand to have a little more fat over his ribs and be just fine. This indicates to me that maybe he is not as easy of a keeper as I initially thought. Using the Condition Score System I would rate JB as a 5 for Moderate.

I will also have to keep in mind that he is a stallion and he tends to drop weight a little quicker, especially in the spring. If he is breeding this coming spring and is also maintaining a moderate to heavy conditioning program , these amounts will have to go up in order for him to continue to maintain.

The next step was to figure out exactly what JB’s daily nutrient requirements are for his level of work. There are several resources out there to help you with this. I reviewed several others out there, all of which are close to the same . I chose Purdue’s site because I liked the overall article content the best. Virginia Cooperative Extension is also another one that seemed very good as well. I used the charts provided by the Purdue Cooperative Extension. The link to Purdue is

JB is a 6 year old that weighs approx 850 lbs, maybe a bit more than that. He is in good condition and has a lot of room to move. Using table one of the article provided above, I had to do some additional math. The table is broken down by weight of horse and the two closest categories are 880 lbs or 1000 lbs. I probably could have used the 880 lbs and made it easy on myself but being an analytical I wanted to break it down further. That way, knowing JB likely is a bit heavier than 850, I am not too concerned if my #’s come out a bit higher .

I took the 20.1 Mcal/day for the 880lb horses and divided it by 880 lbs = .023 This tells me that for this weight division there are .023 Mcals /lb. I checked this ratio for some of the other weight categories as the numbers of each nutrient value range depending on the weight of the horse. Ironically enough for the 1100 lbs horse it’s almost the same and this should get me plenty close for JB.

Next, I took 850 X .023 to calculate JB Digestible energy; this comes to 19.5 Mcals of Digestible energy.

I followed the same logic for each requirement on the chart using the numbers from the 880 lbs line to calculate for JB’s weight.

After some number crunching and tedious note taking, I finally have the Daily Requirements for JB.

JB Needs:
Digestible Energy= 19.5 Mcals per day
Crude Protein= 1.7 lbs per day
Calcium= 24.15 grams per day
Phosphorus= 16.42 grams per day
Vitamin A = 17.4 IU per day.

My next steps are to calculate what JB is actually receiving in nutrient levels for his hay and grain. I have started that process but have run into a few snags because of the hay type we are feeding. The Purdue article has a chart listing the nutrient amounts for various hays. We are feeding a blended hay which is a combination of orchard , crested wheat , timothy and even a little Alfalfa. Crested wheat is not one that the article lists. I tried calculating it using the orchard and timothy but the majority of the hay is the wheat grass .

After a lot of hunting I have found another website that has the wheat grass listed. Thus site is and is more of an online tool that allows you to choose from a variety of forages. The down fall is that most of the values are in percentages rather than grams or pounds. I will have to do some additional math wizardry and a math student I am not.

I am working on that next phase of the calculation.

Stay tuned !

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