ASC-12 BALANCING RATIONS (2024)

BALANCING RATIONS
ISSUED: 6-72
REVISED: 6-91
John T. Johns, Roy Burris, Nelson Gay and David Patterson

Because feed costs are the major costof producing beef, making the most efficient use of feeds is of prime importancein determining profits. Rations must be properly balanced for cattle touse feeds most efficiently. Ration balancing is another management toolthe efficient producer can use to maximize profits.
To begin ration balancing, some basicinformation about frequently used terms is needed. A ration is theamount of feed an animal receives in a 24-hour period. A balanced rationis the amount of feed that will supply the proper amount and proportionsof nutrients needed for an animal to perform a specific purpose such asgrowth, maintenance, lactation or gestation.
Nutrients are any feed componentor group of feed components that are similar in chemical composition andthat aid in the support of animal life. Examples of nutrients are proteins,carbohydrates, fats, minerals and vitamins. Nutrient requirementsare the amount of nutrients the animal needs for a specific purpose. Theyare influenced by many factors, such as weight of animal, sex, desiredrate of growth, stage of lactation, environment and others. For beef cattle,nutrient requirements may be found in published tables, such as the "NutrientRequirements of Beef Cattle" published by the National Research Council.
The nutrient composition ofa feed is the amount of specific nutrients contained in the feed. Theyare expressed as a percentage of the dry matter and may also be found inpublished feed composition tables. A word of caution: feed compositiontables contain only average values. Unless your feed is average, the datawould not be accurate.
Feed composition tables should be usedwhen you have no other information. A chemical analysis of the feed canbe done for a limited cost, and it will give much more accurate information,
Common information provided from ananalysis or a composition table will include dry matter, crudeprotein, energy and minerals.
Dry matter is the portion ofthe feed left after all water has been removed. It contains the nutrients.Values for dry matter intake shown in nutrient requirement tables are notall an animal will consume, but represent an amount that can be consumedunder normal circ*mstances.
Different feeds contain different levelsof dry matter; therefore, it is desirable to balance the ration on a drymatter basis and then convert the various feeds back to an as-fed basis.
Crude protein may also be calledtotal protein. It is determined by measuring the nitrogen content of feedand
multiplying by the value 6.25 because proteins typically contain 16%nitrogen. Not all nitrogen-containing compounds are true proteins. Theseare called nonprotein nitrogen (NPN) sources. Many of these NPN compoundscan have their nitrogen converted to microbial protein in the rumen underproper conditions. Generally, NPN sources are not used well as proteinwhen cattle are on high roughage rations or have high protein requirements,such as young cattle with high rates of growth. True protein sources shouldbe used in these cases.
Energy is not actually a nutrient.It is contained in nutrients such as carbohydrates, fats, etc. For practicalpurposes energy will be considered a nutrient. There are several methodsof measuring feed energy values. Some of these are digestible energy, netenergy for maintenance and gain and total digestible nutrients. Total digestiblenutrients (TDN) is the value most commonly used in simple ration balancing.
Minerals are compounds neededto regulate many metabolic functions in the body. They may be classed asmacro or trace minerals depending on the amounts needed. Examples of macrominerals are calcium and phosporus. Iron, zinc and copper are examplesof trace minerals.
Other important nutrients are vitaminsand water. Rations are not normally balanced for these nutrients, but adequateamounts must be provided for desired rates of growth. Water is particularlyimportant because feed intake decreases when water intake is not adequate.
Roughages are feeds that arerelatively high in fiber and low in energy. Hay, straw, cobs, cottonseedhulls and corn stalks are examples of roughages.
Concentrates are feeds or mixturesof feeds that are relatively low in fiber and provide energy as the primarynutrient.

Formulating Rations
A systematic approach will help inration balancing. First, determine the nutrient requirements of the animalbeing fed. This means determining the sex, size and production level ofthe animal. With this information, nutrient requirements are availablefrom a table.
The next step is to determine the feedsavailable for use. List their composition on a dry matter basis from acomposition table or a chemical analysis. Now the amounts of the feedsnecessary to balance the ration can be determined.
The following example will help inunderstanding the first method used. The method illustrated is called aPearson Square. A ration will be balanced for a 500-pound medium-framesteer calf with a desired gain of two pounds per day. The requirementsare shown in Table 1.

TABLE 1. -- Daily Nutrient Requirements (lbs.) For a 500-lb. Medium-FrameSteer, ADG=2.0¹

TABLE 2. -- Nutrient Composition Of Various Feedstuffs, Dry MatterBasis¹

Feeds available and their compositionare shown in Table 2. Energy or TDN will be the first nutrient balancedfor, as the greatest amount of feed goes to satisfy energy needs.
The animal requires a 67.5% TDN ration.To use the Pearson Square method, place the value 67.5 in the center ofthe square. Place the TDN values of fescue and shelled corn on the leftdiagonals of the square and subtract across the diagonal, smallest numberfrom largest. Now, add the two numbers on the right hand side of thesquare. These numbers mean that 22.5 parts of fescue and 19.5 parts ofcorn will give a 67.5% TDN mixture.

Figure 1

There are 42 total parts in the ration. Divide the two numbers on theright side of the square by the total to determine the preliminary percentageof fescue and corn in the ration.

The next step is to calculate thepercentage of crude protein in the fescue-shelled corn mixture and comparewith the animal's requirement. If the requirement is met or exceeded, theration is balanced. If the requirement is not met, protein supplementationand additional balancing are needed.
Determine the percentage of crude proteinin the fescue-shelled corn mixture by multiplying the percentage of eachingredient in the mix by its percentage of crude protein. Add the two resultingvalues for the percentage of crude protein in the total mixture. For example,fescue is 54% of the mix and contains 9.5% crude protein. Shelled cornis 46% of the mix and contains 10.1% crude protein.

The crude protein content of the total mix is 9.7% (5.1 + 4.6 = 9.7%).The animal requires 11.4% crude protein in the ration; thus a deficiencyof 1.7% (11.4 - 9.7 = 1.7%) exists, and protein supplementation is needed.
Use the square method now to balancethe fescue-shelled corn mix and soybean meal for an 11.4% crude proteinmixture. Place 11.4 in the center and 9.7 and 49.9 on the left diagonalsand subtract as before. Add the two figures on the left side of the square(38.5 + 1.7) to determine the total parts of the ration (40.2). Divideeach number on the right diagonal (38.5 and 1.7) by the total parts inthe ration (40.2) to determine the percentage of the mixture composed offescue and shelled corn (95.8%) and soybean meal (4.2%).
Fescue / shelled corn mix

Figure 2

Now, determine the pounds of drymatter each feed ingredient contributes to the total. This is done by multiplyingthe pounds of daily dry matter consumed (13.1) by the percentage each ingredientcontributes to the total. The protein supplement, in this case soybeanmeal, must be calculated first.

Daily

Now, determine the pounds of daily drymatter available for fescue and shelled corn by subtracting the poundsof protein supplement dry matter from the daily dry matter.

There are 12.55 pounds of dry matter composed of the fescue-shelledcorn mixture.

To determine the individual pounds offescue and shelled corn, multiply the pounds of dry matter composed ofthe fescue-shelled corn mixture by the percentage of fescue or shelledcorn determined in the first square. Subtract this value from the totalpounds of fescue-shelled corn dry matter to obtain the pounds of dry matterof the second ingredient. In this example, fescue dry matter would be 6.77pounds (12.55 lbs.x .54 = 6.77 lbs.), and shelled corn dry matter wouldbe 5.78 pounds (12.55 lbs. - 6.77 = 5.78 lbs.).

Pounds of fescue dry matter:
12.55 x .54 = 6.77 pounds of fescue dry matter

Pounds of shelled corn dry matter:
12.55 - 6.77 = 5.78 pounds of shelled corn dry matter

Now, each dry matter quantity mustbe converted to as-fed quantity so the farmer knows how much to actuallyfeed. This is done by dividing the pounds of dry matter by the percentdry matter of the feed ingredient.

Thus, the daily ration for thissteer becomes 7.35 pounds of fescue, 6.56 pounds of shelled corn and .67pounds of soybean meal.
Determine the calcium and phosphorussupplied by each ingredient and compare to the daily requirements to decideif a mineral supplement is needed. This is done by multiplying the drymatter pounds of each feed in the ration by its calcium and phosphoruscontent and adding the results. The results are compared to the animal'sneeds; then an excess or deficiency can be determined.

Pounds of

Phosphorus level of the ration is adequate,but a deficiency of calcium exists. Minerals are generally supplied byfree-choice supplementation with commercial mineral supplements or homemixtures.
A second method of ration balancingmay simply be termed trial-and-error formulation. In this method, a rationis estimated, and the nutrient content calculated. These results are thencompared to the nutrient needs of the animal for which the ration is beingbalanced. Deficiencies are corrected by changing proportions of feeds inthe rations or by substituting or adding ingredients.
The following example will help inunderstanding. The same systematic approach is necessary. Knowledge ofanimal nutrient requirements, feeds available and their nutrient compositionare still necessary. For this example, a 1000-pound cow in the last one-thirdof gestation will be used. Her nutrient requirements are shown in Table3. The same feeds as in the previous example will be used. Their nutrientcomposition is shown in Table 2.

TABLE 3. -- Nutrient Requirements (lbs.) for a 1000-lb. Mature Cow,Final Trimester Of Gestation¹

As hay is the primary source of nutrientsfor most cows, this example will begin by assuming that all of the drymatter being consumed is coming from fescue hay. This means the cow iseating 21 pounds of actual fescue hay daily (lbs. of dry matter 19.6 dividedby the percentage of dry matter .92 equals 21 pounds).
Next, calculate the nutrients suppliedby fescue and compare them to the cow's need. The nutrients supplied aredetermined by multiplying the pounds of dry matter of the feed consumedby the feed's nutrient content on a dry matter basis. In this example,fescue supplies 9.4 pounds of TDN, 1.86 pounds of crude protein, .058 poundsof calcium and .05 pounds of phosphorus. A comparison with nutrient needsshown in Table 3 reveals an energy deficiency of 1.1 pounds of TDN.
An addition of corn grain is necessaryfor extra energy. We cannot simply add corn because the daily dry matterintake would be exceeded and cattle might not be able to consume this amount.Corn must be substituted for fescue. This means we will gain nutrientsfrom corn, but we will also lose nutrients from the fescue. The net effectof substituting corn for fescue must be determined.
One pound of fescue dry matter contains.48 pounds of TDN while one pound of corn dry matter contains .90 poundsof TDN. The net effect of replacing one pound of fescue dry matter withone pound of corn dry matter is a gain of .42 pounds of TDN (.90 - .48= .42).
A deficiency of 1.1 pounds of TDN exists.Dividing the pounds of nutrient deficiency by the pounds of nutrient netgain will tell us the pounds of dry matter to substitute. For example:

1.1 pounds TDN needed
= 2.6 pounds of corn dry matter substituted for 2.6 pounds of fescue drymatter
.42 pounds TDN net gain

Now the ration is 17 pounds of fescue dry matter and 2.6 pounds of shelledcorn dry matter.
Calculate the nutrients supplied bythe substituted ration and compare to the cow's nutrient need. The comparisonis shown in Table 4. As can be seen, all nutrient needs are met or exceeded.The ration is balanced for the nutrients desired.
Now, convert pounds of dry matter topounds as fed as done for the previous ration. Divide pounds of dry matterby percent dry matter. Thus the daily ration actually fed becomes 18.5(17 ÷ .92) pounds of fescue and 2.95 (2.6 ÷ .88) pounds ofshelled corn.
Animals will gain more efficientlyand economically with a balanced ration. By using these guidelines, youshould be able to balance rations that will meet the needs of most farmanimals.

TABLE 4. -- Nutrient Content of the Substituted Ration and Comparisonwith Requirements

TABLE 5. -- Nutrient Requirements of Selected Groups of Beef Cattle^a,b

TABLE 6. -- Composition of Commonly Used Feeds (dry matter basis)NRC 1984.