Tuesday, January 06, 2009

ARTICLE

Understanding U.S. Feed Tags And Balancing a Dairy Goat Ration

Irene Brown-Crowder, Dr.

Published: July 23, 2003

An introduction to the interpretation of the information found on feed tags and how to use it when balancing rations for dairy goat

Introduction

Editor’s note: This article discusses US feed tags; however, the principles will apply to any country.

Every producer needs to understand how to read a feed tag, in order to purchase the product that best meets the goat’s needs. In addition, balancing a feed ration with the forage available to the producer is extremely important. Some goat owners already have their own custom mix while others are purchasing a commercially designed bag of feed from the store or cooperative.

The feed mill

There are several terms in feed formulation that will determine the price of the final bagged product.

Open Formula - the formula can be changed to meet the fixed contract price.
For example, 15% crude protein and 70% energy could be made up of corn and soybean meal or corncobs, soybean meal, fat and urea. The purchased feed may look different from week to week.

Closed Formula - the formula can not change but the price of the feed fluctuates. This is also known as the custom formula.
For example, 1000 pounds of corn, 400 pounds of soybean meal, 300 pounds of oats, 380 pounds of barley and 20 pounds of trace mineral salt, vitamins and minerals. This week it costs $9.00 per 50 pound bag, next week it cost $7.80 per50 pound bag and the following week the price is different. It relates to the cost of each ingredient and how it fluctuates on a weekly basis. The purchased feed should not look different from week to week unless a change was made in the formula.

Open/Closed Formula - This formula is an in between term used by feed companies.
They will use some guarantees on quantity of feed ingredients and allow other ingredients to fluctuate within the formula. One week it may be oats, and the next week it may be barley or wheat. This depends on what ingredient will hold the same price from week to week. Most of the time, the feed looks similar from week to week.

The feed tag

The feed tag found on commercial feeds or concentrates are a legal requirement of state regulatory agencies. These regulators belong to the American Association of Feed Control Officials (AAFCO). This organization provides guidance to the Feed Control Service Administrators concerning identification of feedstuffs, feed mixtures, feed additives, minerals and vitamins. The Regulatory Service personnel monitor and test feeds in their laboratory and notify manufacturers if their analysis does not match the feed tag guarantees. In addition, other feed testing laboratories are members of AAFCO and submit results of unknowns and standards every month to insure the laboratory is functioning properly.

The feed tag must identify any medication or drugs and their concentration level, along with any warnings (i.e. group of animals to feed) and withdrawal times. Examples of medications that might be found in US goat feeds are Lasalocid, Rumensin, Decoquinate, and Chlorotetracycline.

Feed tags usually have a guaranteed analysis section along with an ingredients listing. In the analysis section, minimum and maximum levels are listed. Crude protein is usually the first item listed in the analysis section. The tag may read: Crude Protein (CP) not less than X% or Crude Protein, min ....X%. If protein sources not from animal or plant ingredients are included, the tag may read, “This includes not more than X% equivalent crude protein from non-protein nitrogen (NPN)”. The other sources may be urea or ammonium chloride.

The next item is usually Crude Fat and may read: Crude fat not less than X% or Crude Fat, min ....X%. The minimum fat requirement for dairy goats is not known, but 1 to 5 % fat in goat rations seems to be adequate. Some research indicates that certain bypass fats can be included beyond the 5% crude fat level without disrupting rumen function.

Crude Fiber not more than X% or Crude Fiber, max ....X% is usually the next item in the analysis section. As this number increases, the digestible energy of the feed decreases. The price should reflect the lower energy in most cases. If you are feeding a complete commercial ration that is considered a TMR or BIR, check the level of fiber. You may need to feed hay in addition to the commercial supplement to avoid any metabolic problems.

Some tags may include minimum and/or maximum levels of minerals, vitamins and preservatives. Check these levels with the forage fed to the animals to make sure the animal’s requirements are met.

The ingredients listing on the tag will not always identify individual feedstuffs. Instead, categories of feedstuffs such as processed grain by-products (i.e. brewer’s grains, bran, hominy), grain products (i.e. corn, oats, barley, wheat), plant proteins (i.e. soybean meal, cottonseed meal, canola meal, etc.), forage products (i.e. alfalfa meal or leaf meal) and molasses products (i.e. cane or beet molasses, wood molasses) are used. In addition, roughage products could include cottonseed, soy, rice other types of hulls or ground hays. The total must be shown as a percentage. Be aware that roughage products may cause the crude fiber guarantee to seem abnormally high (16 to 26% or more); therefore, lowering the digestible energy of the feed.

Mineral Tag Dissection

Determine the amount of Dicalcium Phosphate (Dical)
A. % Phosphorus divided by 18.5 = % Dical
B. % Dical x 2000 pounds = pounds of Dical in 1 ton
Example: 10% divided by .185 = 54%
2000 pounds x .54 = 1080 pounds of Dical per ton
Determine the amount of Calcium.
A. Pounds of Dical x .215 = pound of calcium from Dical
B. Total Calcium (% Ca x 2000) - Calcium from Dical = Calcium added from Limestone.
C. Calcium from limestone divided by 3.38 = pounds of Limestone per ton.
Example: 1080 x .215 = 232.2
2000 x .21 = 420 pounds total calcium - 232.2 = 187.8
187.8 divided by .38 = 494 pounds of limestone per ton.
Salt amount on the tag.
If you have 12% salt on the tag ........
2000 pounds x .12 = pounds of salt in 1 ton of premix
Assume 20 - 50 pounds for trace minerals and vitamins.
Urea Equivalent:
% protein equivalent from NPN divided by 2.81 = % urea in mix.

Milk Replacer Tag

1. Look at the guaranteed analysis and ingredient listing. Most milk replacers will range from 20 to 30% in Crude Protein and 15 to 25% Crude Fat. This is a very wide range to work with and you may want to dilute a more concentrated product to meet the particular animal’s needs.
2. The ingredient listing will list products such as Dried Whey, Dried Whey Product, Soy Protein Concentrate, and Dried Whey Protein Concentrate. The cost of the milk replacer will reflect the composition of the replacer. By adding more Soy Protein Concentrate, the price may be reduced. Young animals do not perform as well on an all Soy protein milk replacer.

Calculating a Dairy Ration

A ration for dairy goats should supply the nutrients for 1) maintenance, 2) growth, 3) milk production and 4) reproduction. The nutritional requirements for goats can be found in the National Research Council (NRC) Nutrient Requirements of Goats (1981). This will provide a starting point. Consulting a nutritionist is recommended. Be sure to have laboratory analyses for any forage used. Book values may be used, but they may not be accurate.

The Pearson Square Method is an easy way to determine the amount of grain and commercial protein supplements to obtain a desired percent protein or energy in a ration.

Precautions about using the Pearson Square are: 1) It can only be used for two feed materials: however, either or both of these can be mixtures, and 2) the number in the center of the square must be intermediate to the two numbers at the left corners. For example, any combination of a 10% protein grain and a 46% protein supplement would have to have a protein content between 10 and 46%. Always check this, because the Pearson Square will give an answer if the number in the center in not intermediate to the other two even though such an answer is incorrect.

Example:
Prepare a 100 pound ration that contains 16% protein using corn (9% protein and a commercial protein supplement (40% protein). The commercial protein supplement would contain all necessary minerals, salts and vitamins.

Corn 9%    24 parts corn
16
Supplement 40%   7 parts supplement
    31 total parts

24/31 = 77.4% corn                                       7/31 = 22.6% supplement
77.4% corn x 2000 = 1548 pounds of corn
22.6% supplement x 2000 = 452 pounds supplement
The check point is 1548 + 452 = 2000 pounds

Subtract across the diagonals of the square (16 - 9 = 7, 40 -16 = 24).
Add the two numbers on the right side of the square (24 + 7 = 31).
The proportion of the corn in the final mix will be: 24/31 or 77.4%.
The proportion of the supplement will be 7/31 or 22.6%.
To mix one ton of feed requires 1548 pounds of corn (.774 x 2000) and 452 pound of supplement (.226 x 2000).

The Algebraic Method for two ingredients is basically the same method as the Pearson Square, and is used for he same purpose. Using the example above, let X represent the pounds of corn and (100 - X) represent the pounds of supplement in each 100 pounds of final mix.

The corn supplies .09 pound of protein per pound of corn.
The supplement supplies .40 pounds of protein per pound of supplement.
Each 100 pounds of the final mix will contain 16 pound of protein, (16% of 100 = .16 x 100 = 16).
Then .09X + .40 (100 - X) = 16.
Solving for X, X = 77.4 pound of corn.
Then 100 - X = 22.6 pound of supplement.
Conversion to a ton basis is the same as with the Pearson Square.

The Substitution method may be used alone or in combination with other methods. Using the above examples will illustrate the principle of this method.

One hundred pounds of corn provide 9 pounds of protein.
For each pound of corn replaced with a pound of supplement, there is an increase of .31 pounds of protein in the total (.40 - .09).
If the desired increase in protein is 7 pounds, (16 desired - 9 present in corn), then the number of pounds to be substituted is 7/.31 = 22.6.

The Simultaneous equations may be used for simple balancing, and will also work for more complex problems, such as balancing two ingredients for two nutrients at once. For example, corn (9% protein, 90% TDN) and hay (16% protein, 50% TDN) are to be used to formulate a ration containing 11 pounds protein and 60 pound TDN. Let X = pounds of corn and Y = pounds of hay.

Set up the protein equation: .09 X +.16Y = 11.
Set up the TDN equation: .90 X + .50 Y = 60.
Multiply each number of one equation by a number which will make either the X or the Y coefficients of both equations equal. In this case, multiplying the protein equation by 10 gives: .90X + 1.60Y = 110.
Subtract one equation from the other:
.90 X + 1.60 Y = 110
- (.90 X + .50 Y = 60)
_________________
0 + 1.10 Y = 50
Solve for Y, Y = 45.6.
Substitute this value of Y in either equation and solve for X: .90 +.50 (45.6) = 60; .90 X = 37.2: X = 41.4.
Substituting theses values into both equation will confirm that a combination of 41.4 pounds corn and 45.6 pound of hay will contain 11 pound protein and 60 pounds TDN.

The Combination of Methods can be used when the balancing of three ingredients for three nutrients, four ingredients for four nutrients, etc. and solved by matrix algebra. Most of the time, it is easier to turn such problems over to a computer systems.

Example: If a ration is to contain 12% protein, 68% TDN, .40% calcium and .305 phosphorus on a dry matter basis, and the feeds available are rolled corn, corn silage, soybean meal, ground limestone, and dicalcium phosphate, the balancing can be done by a combination of algebraic and substitution methods. When wet feeds such as corn silage are used, it is often desirable to balance the ration with nutrient values expressed on a dry matter basis, as in the following example.

Balance for TDN using algebraic or Pearson Square methods. If corn grain is 90% TDN and corn silage is 62% TDN (dry basis), then the desired 68% TDN level is provided by 21.4 pounds corn and 78.6 pounds of silage dry matter per 100 pounds.
           Corn 90%   6 parts corn
                           68
          Corn Silage 62%    22 parts supplement
                                      28 total parts

6/28 = 21.4% TDN corn   22/28 = 78.6% TDN silage
If corn is 10% protein and silage is 8.5% protein (dry basis), then the above mixture will contain only 8.8 pounds (%) protein. (.10 x 21.4) = (.085 x 78.6). The additional 3.2 pounds must be made up with soybean meal (50.1% protein).
For each pound of grain/silage mixture replaced with soybean meal, there is an increase of .413 pounds protein (.501 pounds from soybean meal - .088 pound from grain/silage). The number of pounds to substitute is 7.7 pounds (3.2/ .413). The grain/silage mixture is reduced to 92.3 pound, or 19.8 pounds of corn (.923 x 21.4) and 72.5 pounds silage (.923 x 78.6) on a dry basis. The soybean meal could have replaced either grain or silage instead of both. Since the TDN of soybean meal is 80%, substituting it for the mixture raises the TDN value slightly, but not as much as if the substitution had been for silage only. If soybean meal had been substituted for corn grain, the TDN of the mixture would have been reduced.
The mixture of 19.8 pounds of corn, 72.5 pounds of silage and 7.7 pounds of soybean meal must now be balanced for calcium and phosphorus. Since phosphorus is the more expensive to supplement, balance for it first. If the phosphorus levels of corn grain, corn silage and soybean meal are .295, .20% and .75%, the total level of the mixture is .26%. (.0029 x 19.8) + (.0020 x 72.5) + (.0075 x 7.7).
To supply the needed .04 pounds (.30 - .26) of phosphorus, .22 pound of dicalcium phosphate are needed (.04/.185). This is such a small amount that it can be substituted for corn silage, pound for pound, or simply added on without making any real change in the level of protein or TDN in the mixture.
Calcium level should be checked. If calcium level of corn is .02%, silage is .27%, soybean meal is .36%, and dicalcium phosphate is 24.5%, then the calcium level of the mixture at this point is .28%. (.0002 x 19.8) + (.0027 x 72.28) + (.0036x 7.7) + (.245 x .22).
An additional .12 pounds of calcium (.40 - .28) must be added. If limestone is 38% calcium, then .32 pounds of limestone must be added (.12/.38). As with dical, this may be substituted for silage or simply added.
The final mixture will then be 19.8 % corn 71.96% corn silage, 7.7% soybean meal, .22% dicalcium phosphate and .32% limestone, on a dry basis. To convert to an as-fed basis, each percentage is divided by the dry matter content of the fed (Dry matter = 100 - moisture).

Ingredient pounds of dry matter % dry matter pounds as- fed % of total as-fed

Rolled corn 19.80 88 22.50
11.74

Corn Silage 71.96 45 159.91 83.42

Soybean meal 7.70 88 8.75
4.56

Dical phosphate .22 100 .22 .11

Limestone .32 100 .32 .17

TOTAL 100.00 191.7 100.00

Once you have determined the feed mixture that fits your forage, take it to the feed mill and ask them to price it. Pricing will depend on how much of the feed can be purchased and stored at one time on your farm. In addition, if your purchased feed looks different than it usually does, take several feed samples from several bags and save it. Be sure to date it and keep a copy of your feed tag for that batch. If you are unhappy with the feed, call your feed dealer and ask to exchange the feed.