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Balancing Rations. Animal Science II Unit 8. Classifying Rations. Roughages M ore than 18% crude fiber when dry Hard to digest Include: hay, silage, pasture, fodder* 2 classes: Legume and Non-legume Legumes*

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balancing rations

Balancing Rations

Animal Science IIUnit 8

classifying rations
Classifying Rations
  • Roughages
    • More than 18% crude fiber when dry
    • Hard to digest
    • Include: hay, silage, pasture, fodder*
    • 2 classes: Legume and Non-legume
  • Legumes*
      • take nitrogen from the air, it is fixed in the plan by bacteria and made available for use
  • Nonlegume*
      • can not use nitrogen from the air, usually lower in protein
      • Most common livestock feeds
classifying rations1
Classifying Rations
  • Concentrates
    • Less than 18% crude fiber when dry
    • 2 classes-protein supplements & energy feeds
    • Protein supplements*
      • Contain 20% or more protein
      • 2 groups based on source- animal and vegetable
    • Commercial supplements*
      • Made by commercial feed companies
      • Mixes of animal and vegetable protein feeds
      • Each is usually made for only 1 class of animal
  • Energy feeds
    • Less than 20% crude protein*
    • Most grains*
    • Corn is the most widely used*
ration characteristics
Ration Characteristics

Ration-the amount of feed given to an animal in a 24 hour period

Balanced ration-a ration that has all the nutrients needed in the proper proportions.

Must be palatable, balanced for species, age, and function

ration functions
Ration Functions
  • Maintenance
    • Maintaining the life of the animal*
  • Growth
    • Can only be met after maintenance needs are met*
  • Fattening
    • Can only be met after maintenance and growth needs*
  • Production
    • Kinds of nutrients needed depend on the type of production sought.*
  • Work
    • Energy needed comes from carbohydrates, fats and extra protein in the ration*
    • Other needs of the body must be met first.*
balancing rations1
Balancing Rations

Ration must meet the needs of the animal

Nutrient allowance should be met as closely as possible and not more than 3% below.

Ration must contain a certain amount of dry matter

protein in the ration
Protein in the Ration
  • Measured by
    • Total Protein (TP)
    • Digestible Protein (DP)
  • Essential amino acids must be included for nonruminents
  • Acceptable to allow 5-10% more protein in the ration than the animal need, however too much protein will raise the cost of the ration.
four methods of measuring energy provided by the ratio
Four Methods of Measuring Energy Provided by the Ratio

Digestible Energy (DE)

Total Digestible Nutrient (TDN)

Metabolizable Energy (ME)

Net Energy (NE)

See fig 8-1


2,000 pounds of feed is needed to feed a 100 pound growing hog. A feeding standards table shows that a 14% crude protein ration is needed. Corn and soybean meal are selected as feeds. A feed composition table shows that corn is 8.9% and soybean oil meal has a 45.8% crude protein on as-fed basis. How much corn and how much soybean meal is needed to be mixed together for 2,000 pounds of feed.

step 1

Draw a square with lines connecting the opposite corners. Write the percent of crude protein needed in the center of the square.


step 2

Write the feeds to be used and their crude protein percents at the left hand corners of the square.

Corn 8.9


Soybean Meal 45.8

step 3

Subtract the smaller number from the larger along the diagonal lines. Write the difference at the opposite end of the diagonals.


Corn 8.9







SBM 45.8


step 31

To check to ensure that the square is setup correctly find the sum of the numbers on the right should equal the difference of the numbers on the left.

Corn 8.9



SBM 45.8




step 4

Divide the parts of each feed by the total parts to find the percent of each feed in the ration.

Corn 31.8/36.9 x 100= 86.2%

SBM 5.1/36.9 x 100= 13.8%

step 5

It is known that 2,000 pounds of the mixture is needed. However, we need to know how much of each grain is needed to make the 2,000 pound mixture. This done by multiplying the percent of corn in the mix by the total pounds of the mix.

2,000 x 0.862= 1,724 lbs of corn

2,000 x 0.138= 276 lbs of soybean meal

step 6

Check the mix to make sure the protein need is met.

1,724 lbs of Corn x 0.089= 153 lbs of corn protein

276 lbs of SBM x 0.458= 126 lbs of soybean protein

153 + 126= 279 pounds of protein total

279/ 2,000 x 100= 14%

The mix is balanced for crude protein!


Assume that a 2,000 pound mix of corn, oats and soybean meal is needed. The mix is to contain 16% digestible protein. A decision is made to use ¾ corn and ¼ oats in the mix. Thus the proportion of corn to oats is 3:1. How many pounds of corn, oats, and soybean meal are needed?

step 11
Step 1

The weighted average percent protein in the corn and oats is found first. Multiply the proportions of corn by the percent digestible protein in the corn. Do the same for oats. Add the two answers together and divide by the total parts. The answer is the weighted average percent of digestible protein in the corn-oats mix.

Corn 3 x 7.1= 21.3

Oats 1 x 9.9= 9.9


31.2/4= 7.8% digestible protein in the corn-oats mix.

step 21
Step 2

You then use the Pearson Square as in you did in example 1.

3 parts corn plus 1 part oats 7.8



SBM 41.7




step 41

25.7/33.9 x 100= 75.8% corn-oat mix

8.2/33.9 x 100= 24.1% SBM

step 51

0.758 x 2,000= 1516 lbs corn-oat mix needed

1516 lbs x .75 (3/4)= 1,137 lbs of corn needed

1,516 lb x .25 (1/4)= 379 lbs of oats needed

.241 x 2,000= 482 lbs soybean meal needed

step 61
Step 6

Check the mix.

1516 x .078=118.2

482x .417=200.9

200.9 + 118.2= 319.1

319.1/2,000= 0.159= 16%

The ration is balanced for digestible protein.