Feeding the boys, part VI

DISCLAIMER: I am not a vet or an equine nutritionist. This information is purely based on research I have done myself. Please do not mistake my research for actual advice on what to feed your horse. I'm just sharing my experiences so that other horse owners can have the information.

This is the sixth in a series on how I'm determining what to feed my two horses. For Part IV, visit here.

In the last installment, we calculated the NSCs of Saga's ration, along with the Selenium and Vitamin E content of Red's ration. We also discussed how important it is to read feed bag labels and feed according to the recommended quantities for your horse's weight and level of work.

On your own
At this point, the really important thing to know is how to determine how much of a particular nutrient your horse is getting, and how much of that nutrient he actually needs. Finding out what your horse actually needs is a little challenging, but there are two fairly good sources I've been using:

• Equi-analytics web site
  
• Equine Nutrition and Feeding, by David Frape

Based on these two sources, I've created a table that shows the most common nutrients and the recommended daily allowances for mature horses in light work.

Nutrient	Equi-analytics recommendation (for an 1100 pound horse)	Nutrition & Feeding recommendation
Crude Protein	820 g/day	1.08 g/kg BW/day
Lysine	29 g/day	0.054 g/kg BW/day
Crude Fat	-	5%
Calcium	25 g/day	60 mg/kg BW/day
Phosphorus	17.8 g/day	36 mg/kg BW/day
Magnesium	9.4 g/day	19 mg/kg BW/day
Iron	335 mg/day	0.8 mg/kg BW/day
Potassium	31 g/day	57 mg/kg BW/day
Copper	84 mg/day	0.2 ppm/kg BW/day
Zinc	335 mg/day	0.8 ppm/kg BW/day
Manganese	335 mg/day	0.8 ppm/kg BW/day
Selenium	0.8 mg/day	0.002 mg/kg BW/day
Vitamin A	22500 IU/day	45 mg/kg BW/day
Vitamin D	2510 IU/day	6.6 mg/kg BW/day
Vitamin E	669 IU/day	1.6 mg/kg BW/day
Biotin	-	0.2 mg/kg BW/day
Iodine	-	0.007 mg/kg BW/day
Cobalt	-	0.001 mg/kg BW/day
Thiamine	-	0.06 mg/kg BW/day
Riboflavin	-	0.04 mg/kg BW/day

One thing that is interesting to note is that the sources don't always agree with each other about the recommended quantities. For example, Equi-analytics recommends that Saga get 820 g/day of protein, while Nutrition & Feeding recommends 540 g/day (1.08 g x 500 kg). On the other hand, for Potassium, Equi-analytics recommends 31 g/day, and Nutrition & Feeding recommends 28.5 g/day (0.057 g x 500 kg). I don't know who's right, but at least I've got some ballpark numbers to work with!

And now, more math
I promised to calculate the quantity of protein, fat, calcium, and phosphorous that the boys were getting, since these are often the nutrients people look at most. For simplicity, I'll do all the calculations for Saga, and assume he weighs 500 kg.

Saga should get between 540 and 820 g/day of protein.

• Purina Ultium is 11.7% protein, and Saga gets 9 lbs of it daily. That's a total of 1.053 lbs of protein/day (9 lbs x .117)
• Bermuda hay is 10.6% protein, and Saga gets 15 lbs of it daily. That's a total of 1.59 lbs of protein/day (15 lbs x .106)
• Add these together and you get 2.643 lbs of protein/day. Converted to grams, that's 1198.844 g/protein/day. He's definitely not hurting for protein!

Saga should get 5% of his diet as crude fat.

• Purina Ultium is 12.4% fat, and Saga gets 9 lbs of it daily. That's 1.116 lbs of fat/day (9 lbs x .124)
• Bermuda hay is 1.8% fat, and Saga gets 15 lbs of it daily. That's a total of 0.27 lbs of fat/day (15 lbs x .018)
• Add these together and you get 1.386 lbs of fat/day. Since he gets a total of 24 lbs of feed daily, that's 5.8% fat/day. So, he's right in line.
  

Saga should get between 25 and 30 grams of Calcium per day. Calcium calculations are a little trickier, since most feed bags give a min and a max amount, in percentages. We'll calculate both to figure out the range

• Purina Ultium is 0.85 - 1.0% Calcium, and Saga gets 9 lbs of it daily. That's 0.07 - 0.09 lbs of Calcium/day.
  
• Bermuda hay averages 0.5% Calcium, and Saga gets 15 lbs of it daily. That's a total of 0.075 lbs of Calcium/day.
  
• Add these together and you get 0.145 - 0.165 lbs of Calcium/day. Convert to grams and you get between 65.7 - 74.8 g/day. That's more than double what he's supposed to get. But what's really important is that he is getting a Ca:P ratio of about 2:1. So let's calculate P.
  

Saga should get between 17.8 and 18 grams of Phosporous per day.

• Purina Ultium is 0.5% Phosporous, and Saga gets 9 lbs of it daily. That's 0.045 lbs of Phosporous/day.
  
• Bermuda hay averages 0.19% Phosporous, and Saga gets 15 lbs of it daily. That's a total of 0.0285 lbs of Phosporous/day.
  
• Add these together and you get 0.0735 lbs of Phosporous/day. Convert to grams and you get between 33.3 g/day. That's more than a third more than what he's supposed to get. However, if he's getting ~66 g of Calcium/day, then the ratios of the two minerals are about right.

On that note, I'll leave you to your own calculations. Are your horses getting what they are supposed to in the ratios they are supposed to have them?