Horse Nutrition

Bulletin 762-00

Balancing Feed Rations

There have been several methods devised for developing feed rations for horses. Most methods are based upon a trial and error basis, making substitutions until all factors balance in the ration. Many people do not care to make their own ration, preferring to buy commercial mixes. Mixes made by respectable feed manufacturers are very good. If you are feeding only a few horses or do not want the hassle of always having to check the nutrient levels of your feed, commercial mixes are a good way to meet the needs of the horse. However, you need to know which commercial mix to buy to match the feeds that you may already be feeding.

The general rules given here will help the horse owner to either mix his/her own feed or help the one who buys commercial feeds to make wise decisions as to which feed to buy and how much to feed:

1. If you feel that a vitamin deficiency may exist because of the quality of the feed or the stress of the animals, an ADE vitamin premix for either swine or cattle can be added to the mix at the rate of 5 lb. per ton of feed. If you are raising foals, you may want to also add 15 lb. of brewers dried yeast per ton of creep ration to provide B vitamins. Table 7 lists the vitamin requirements for horses. Caution: Do not overfeed vitamins.
   
   
2. Grains are high in phosphorus, low in calcium. Legume hays are high in calcium, low in phosphorus. Grass hays are correct in the ratio of calcium to phosphorus, but are too low in both for horses under two years of age and pregnant or lactating mares. Most commercial rations are balanced at a calcium to phosphorus ratio of 1:1. Therefore, if you are feeding pure alfalfa hay, you may have an incorrect mineral ratio and may need to supplement the diet with more phosphorus. Some horse feeds are made to feed with specific types of hays to correct this problem. Table 5 lists minerals commonly used to balance the calcium-phosphorus ratio.
   
   
3. Trace mineralized salt should be added to all grain rations at the rate of 1% per ton of feed.
   
   
4. If minerals and salt are to be added to the concentrate, liquid molasses will need to be added to bind the fine particles to the grains, or the concentrate will need to be pelleted. If molasses is added, it should not exceed 7% to prevent clumping in cold weather if the concentrate is to be augured out of a bin. Most commercial grain mixes contain 5 to 10% molasses.
   
   
5. Use the body condition scoring discussed earlier to feed horses. If the horse is getting thin, add more feed or increase the concentrate portion of the diet. If the horse is getting fat, decrease total feed or the concentrate portion of the ration.
   
   
6. If you feed a highly concentrated ration (all the needed nutrients in a small volume) such as a complete pelleted ration, horses are more likely to chew on wood out of boredom or to get more fill for their digestive tract.
   
   
7. Most rations are best when kept simple. Adding a lot of different grains and various supplements does not necessarily improve a ration and often may make it economically wasteful or even dangerous.
   
   
8. Energy needs are best met by grains, and protein needs are met by legume hays or protein supplements.
   
   
9. Remember, a ration is the total feed intake of a horse for one day and includes both the concentrate and roughage portions.

In general when you approach making a ration, you start by providing adequate protein because it is the most expensive ingredient. Then you check if that ration supplies adequate energy, and if it does not, you begin to adjust proportions of nutrients and/or substitute nutrients to try to end up meeting both energy and protein needs. Then minerals are usually checked last since they can be added without affecting energy or protein very much. Table 1 lists the energy requirements for growing horses. Table 2 lists the percent crude protein that a ration needs to contain for various classes of horses. Table 3 lists the calcium and phosphorus requirements for various classes of horses. Table 4 (see page 36) lists the energy requirements for mature horses. Table 5 lists the nutrient levels of many of the common nutrients used for horses. These tables will be used in balancing rations for various horses using some of the different methods used to balance rations.

Method 1. Approximate Method

Example: Feed a 1,100-lb. two-year-old horse at moderate work (two hours of jogging which includes two race miles 45 minutes apart).

Step 1.

Determine the nutrient requirement.

1. Total feed intake – This should be between 1.5 to 2.0% of body weight. We will use 20 lb. (picked at random within the range 16—22 lb.) total feed intake as an estimate to start.
2. Crude protein (CP) – Table 2 indicates that the ration should be 10% CP if the horse’s ration is at least 1.5% of body weight, which it is.
   20 lb. x 10% = 2.0 lb. of CP required.
3. Digestible energy (DE) – Using Tables 1 and 4, the requirement is 16.5 (maintenance requirement) + 12.54 (from work section of Table 4: 0.57 x 11 x 2 ) = 29.04 Mcal of DE.

Step 2.

Because the horse is working, we can guess that the ration will require about 50% concentrate to meet the energy needs. The other 50% of the ration will be roughage. Start by feeding 10 lb. of hay and determining what nutrients it will supply. We will use an alfalfa-orchardgrass mixed hay that is a 50-50 mix of grass and legume.

10 lb. hay x	16.0% + 10.1%	= lb. CP
	2

Note: The 16.0 + 10.1 is the CP of alfalfa and orchardgrass from Table 5. They are added together and divided by 2 since the hay is half alfalfa and half orchardgrass.

10 lb. hay x 13% (rounded off) = 1.3 lb. CP

10 lb. hay x	1.04 + 0.94	= Mcal of DE
	2

Note: The 1.04 + 0.94 is the DE of alfalfa and orchardgrass from Table 5, again divided by two since the hay is equal parts alfalfa and grass.

10 lb. x 0.99 = 9.9 Mcal of DE

Step 3.

What does the rest of the ration need to provide?

DE=	29.04	required
	- 9.90	supplied by the hay
	19.14	Mcal of DE required in concentrate

The grain of highest Mcal level is corn at 1.75 Mcal/lb. Therefore, it will take 11 lb. of grain to meet the energy needs instead of the 10 lb. we were originally going to use.

11 lb. corn x 1.75 = 19.24 Mcal

CP – A new adjusted total is needed in the ration since we had to add more grain to meet energy needs. 21 lb. of feed x 10% CP =

2.1 lb. CP required

-1.3 lb. CP supplied by the hay

0.8 lb. needed in the grain ration

0.8 lb. = 7.2% – This means our grain must be at least 7.2% protein. All grains exceed this so no protein supplements are needed.

11 lb. corn x 10.9% CP = 1.2 lb. CP

The total ration contains 1.2 lb. CP (grain) + 1.3 lb. CP (hay) = 2.5 lb. CP. The only way to decrease the protein to the level required would be to use poorer quality hay. The extra 0.4 lb. is not enough to be concerned about. Actually, having some excess CP is good since we are relying on a lot of the CP to come from the grain, and we know that the protein quality of grain is less than ideal. The extra can help make up for the lower quality.

Therefore, the ration is:

	DE	CP
10 lb. hay	9.90	1.3
11 lb. corn	19.24	1.2
21 lb	29.14 Mcal	2.5 lb.

 

Step 4.

Check Calcium (Ca) and Phosphorus (P) ratio and levels (Tables 3 and 5).

Ca:
Corn =
0.05% x 11 lb. = 0.0055 lb

Hay =
(Alf) 1.5% + (O.G.) 0.35%, averaged = 0.925%
0.925% x 10 lb. = 0.0925 lb

Total Ca:
0.0055 lb. + 0.0925 lb. = 0.0980 lb

0.0980/21 lb. = 0.476% Ca in total ration

P:
Corn =
0.60% x 11 lb. = 0.066 lb. P

Hay =
(Alf) .25% + (O.G.) 0.31% averaged = 0.28% P
10 lb. x 0.28% = 0.028 lb. P

Total P:
0.066 lb. + 0.028 lb. = 0.094 lb

0.094/21 lb. = 0.44% P in total ration

Ca and P are in balance (1.07:1) in the ration and are in sufficient quantity (0.45% Ca and 0.35% P required from Table 3). For added protection, dicalcium phosphate should be provided free choice along with trace mineralized salt.

Step 5.

Since all nutrients and needs are based on moisture-free values, the ration needs to be corrected to an as-fed basis. Use Table 5 to do the following:

10 lb. of hay x 100 = 11.2 lb. hay
0.89 (% moisture in hay)

11 lb. of corn x 100 = 12.5 lb. corn
0.88 (% moisture in corn)

Total ration as fed would be 23.7 lb.

 

Method 2. Pearson Square

This is another trial-and-error method to balance feed rations. Using the same feeding problem as before, the procedure would be as follows:

Step 1: Determine the nutrient needs. From the last problem: 10% CP, 29.04 Mcal, and 21 lb. of feed.

Step 2: Divide the total Mcal/ lb. of ration = the Mcal level required in the ration. 29.04/21 = 1.38 Mcal/lb. We already know the CP level is 0.10 (10%).

Step 3: Set up and solve the Pearson square.

Mcal (hay) 0.99 Mcal (grain) 1.75

1.38

0.37 parts hay 0.39 parts grain

To set the square up, you place the desired level of Mcal needed in the ration in the center. The Mcal levels per lb. of hay and grain are then placed as shown, and you subtract across the diagonals of the square. This produces the proportions of each of the parts of the ration (the hay and the grain) that need to be fed to meet the energy requirement. To complete the calculations, divide 0.37 by 0.76 (total number of parts) = 48.7% of ration should be hay. Then take 48.7% x 21 (lb. of total ration) = 10.2 lb. of hay. Then divide 0.39 by 0.76 = 51.3% of ration should be grain. Then multiply 51.3% x 21 = 10.8 lb. of grain.

Next you go through the same method using CP. Since the CP of corn is 10.9% and the CP of the hay is 13% and we want a 10% level in the ration, the square is useless since both ingredients exceed the needed level in the feed.

Again, as in the previous example, the feed also needs to be checked for calcium and phosphorus level and balance. The feed also needs to be converted to an as-fed basis as previously done.

The Pearson Square is very useful to help determine the protein level of the commercial grain mix you wish to purchase, and how much of the grain mix to feed with your hay. For example: You are feeding weanlings with a 13% CP hay and you need to buy a grain mix that will produce a 16% CP ration. Set up the Pearson square as follows:

% CP (hay) 13 % CP (grain) 18

16

2 parts hay 3 parts grain

First, we know whatever grain ration is purchased will have to exceed 16% CP since the hay is only 13%. Therefore, select whatever feed mix is available that exceeds 16% (used 18% in problem). From the calculation we can see that it will take 2 parts of hay for every 3 parts of grain fed to balance the ration. If we wanted to feed less grain and more hay to provide more roughage, we would have to buy a higher CP grain mix.

Method 3. Simultaneous Equation Method

If you are an algebra buff, you may want to try this method. The advantage to the system is that it produces a balanced formula for CP and DE in a one-time-through method. The disadvantage of the method, besides the difficulty of the math, is that it may produce answers that are not desirable. For example, it may tell you to feed 2 lb. of hay and 18 lb. of grain which could be dangerous even though it balances mathematically. In such a case, you may need to change the feeds used to produce a more desirable ration.

Example: Feed a weanling (6 mo.) that will mature to 1,320 lb. using corn, soybean oil meal (SBM), hay (50/50 orchardgrass-alfalfa late bloom), and molasses (added to bind SBM and minerals to the grain).

Step 1:

Needs = 16.9 Mcal (Table 1, see page 34) and 16% CP (Table 2)

11.5 lb. total ration (A foal at this age should weigh about 500 lb. x 2.3%)

We will feed 5% of grain mixture as molasses, and grain should be about 50% of the ration. Therefore, 5% x 6 (rounded up from 5.75) = 0.3 lb. which supplies 0.44 Mcal. The CP contributed by molasses is small and of such poor quality that it is not even counted.

Adjusted needs

16.46 Mcal (molasses subtracted)

16.43% CP (The % CP needed in 11.2 lb. to have 16% CP in 11.5 lb. when molasses is added = 11.5 x 16/11.2.)

11.2 lb. total ration (molasses subtracted)

16.46 Mcal = 1.4696 Mcal/lb
11.2

 

Step 2:

Set up equations for 100 lb. of feed

X = hay, Y = corn, and Z = SBM

Equation A: X + Y + Z = 100

Equation B: 0.97X + 1.75Y + 1.63Z = 146.96
(These are the Mcal value per pound for each feed and the total Mcal in 100 lb.)

Equation C: 0.125X + 0.109Y + 0.509Z = 16.43
(These are the CP levels per pound for each feed and the total lb. of protein in 100 lb.)

Step 3:

Solve the equations (Eq).

Eq B		0.97X + 1.75Y + 1.63Z	= 146.96
Eq A x 0.97	=	0.97X + 0.97Y + 0.97Z	=  97.00
Eq D		0.78Y + 0.66Z	=  49.96

Eq C		0.125X + 0.109Y + 0.509Z	= 16.43
Eq A x .125	=	0.125X + 0.125Y + 0.125Z	= 12.50
Eq E		- 0.016Y + 0.384Z	=  3.93

Eq D x 0.384		0.2995Y + 0.2534Z	= 19.18
Eq E x 0.66	=	-0.0105Y + 0.2534Z	=  2.59
Subtract		0.3100Y	= 16.59
		Y = 53.52

Using Eq D

0.78(53.6) + 0.66Z = 49.96 41.8 + 0.66Z = 49.96 0.66Z = 49.96 - 41.8 0.66Z = 8.16 Z = 12.36

Using Eq A

X + 53.52 + 12.36 = 100 X = 34.12

Step 4:

Change X, Y, and Z to pounds fed per day. Check minerals and determine feed on an as-fed basis.

	Lb. dry	DE Mcal	CP lb.	Ca lb.	P lb.	Lb. as fed
Hay	3.8	3.67	0.48	0.0312	0.0103	4.3
Corn	6.0	10.5	0.65	0.003	0.036	6.8
SBM	1.4	2.28	0.71	0.0043	0.0098	1.6
Mol	0.3	0.44	0.0	0.0032	0.0005	0.4
	11.5	16.91	1.84	0.0417	0.0565	13.1

Calcium = 0.04165 lb. / 11.5 lb. = 0.36% (Need 0.70% from Table 3.)

0.0070 x 11.5 = 0.0805 lb. total required minus 0.04165 from above ration leaves 0.03885 lb. to add to balance ration.

Phosphorus = 0.05651 lb/11.5 lb. = 0.49% (Need 0.50% from Table 5.)

0.0050 x 11.5 = 0.0575 lb. total required minus 0.05651 from above ration leaves 0.0014 lb. to add to balance ration.

If you add 0.1 lb. ground limestone and 0.03 lb. dicalcium phosphate, you add 0.0432 lb. Ca and 0.0056 lb. P. This balances the minerals for level, and they are in a ratio of 1.3:1, which is acceptable.

 

Step 5:

Mix 1 ton of the concentrate for this ration. To solve find the percent each ingredient is of the total concentrate using the as-fed weights since feed is bought on that basis. Total concentrate weight is 6.82 (corn) + 1.55 (SBM) + 0.4 (molasses) + 0.1 (calcium) + 0.03 (phosphorus) = 8.9 lb.

Corn
6.82 lb. / 8.9 = 76.6% x 2,000 lb. = 1,533 lb.

SBM
1.55 lb. / 8.9 = 17.4% x 2,000 lb. = 348.3 lb.

Molasses
0.4 lb/8.9 = 4.5% x 2,000 lb. = 89.9 lb.

Ground Limestone
0.1 lb/8.9 = 1.1% x 2,000 lb. = 22.5 lb.

Dical
0.03 lb/8.9 = 0.33% x 2000 = 6.7 lb.

Due to rounding off the total = 2,000.4 lb.

Table 8 shows rations that have been developed and balanced for various levels of protein. In addition to the nutrients listed, vitamins may be added if you feel they are needed. It is also recommended that you have free choice trace mineralized salt and dicalcium phosphate available.