Transcript Balancing Rations

Balancing Rations
ANIMAL SCIENCE II
UNIT 8
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 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-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
 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 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
 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
 Digestible Energy (DE)
 Total Digestible Nutrient (TDN)
 Metabolizable Energy (ME)
 Net Energy (NE)
 See fig 8-1
Using a Pearson's square*
.
EXAMPLE
 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.
14
STEP 2
 Write the feeds to be used and their crude protein
percents at the left hand corners of the square.
Corn 8.9
14
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.
31.8
Corn 8.9
14
SBM 45.8
Parts
Of
Each
Feed
needed
5.1
STEP 3
 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
31.8
14
SBM 45.8
36.9
5.1
36.9
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!
Using the Pearson Square to Mix
Two Grains with a Supplement*
EXAMPLE
 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 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
 31.2/4= 7.8% digestible protein in the corn-oats mix.
Step 2
 You then use the Pearson Square as in you did in
example 1.
3 parts corn plus 1 part oats 7.8
25.7
16
SBM 41.7
33.9
8.2
33.9
STEP 4
 25.7/33.9 x 100= 75.8% corn-oat mix
 8.2/33.9 x 100= 24.1% SBM
STEP 5
 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 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.