ASC-12
BALANCING RATIONS
ISSUED: 6-72
REVISED: 6-91
John T. Johns, Roy Burris, Nelson Gay and David Patterson
Because feed costs are the major cost
of producing beef, making the most efficient use of feeds is of prime importance
in determining profits. Rations must be properly balanced for cattle to
use feeds most efficiently. Ration balancing is another management tool
the efficient producer can use to maximize profits.
To begin ration balancing, some basic
information about frequently used terms is needed. A ration is the
amount of feed an animal receives in a 24-hour period. A balanced ration
is the amount of feed that will supply the proper amount and proportions
of nutrients needed for an animal to perform a specific purpose such as
growth, maintenance, lactation or gestation.
Nutrients are any feed component
or group of feed components that are similar in chemical composition and
that aid in the support of animal life. Examples of nutrients are proteins,
carbohydrates, fats, minerals and vitamins. Nutrient requirements
are the amount of nutrients the animal needs for a specific purpose. They
are influenced by many factors, such as weight of animal, sex, desired
rate of growth, stage of lactation, environment and others. For beef cattle,
nutrient requirements may be found in published tables, such as the "Nutrient
Requirements of Beef Cattle" published by the National Research Council.
The nutrient composition of
a feed is the amount of specific nutrients contained in the feed. They
are expressed as a percentage of the dry matter and may also be found in
published feed composition tables. A word of caution: feed composition
tables contain only average values. Unless your feed is average, the data
would not be accurate.
Feed composition tables should be used
when you have no other information. A chemical analysis of the feed can
be done for a limited cost, and it will give much more accurate information,
Common information provided from an
analysis or a composition table will include dry matter, crude
protein, energy and minerals.
Dry matter is the portion of
the feed left after all water has been removed. It contains the nutrients.
Values for dry matter intake shown in nutrient requirement tables are not
all an animal will consume, but represent an amount that can be consumed
under normal circumstances.
Different feeds contain different levels
of dry matter; therefore, it is desirable to balance the ration on a dry
matter basis and then convert the various feeds back to an as-fed basis.
Crude protein may also be called
total protein. It is determined by measuring the nitrogen content of feed
and
multiplying by the value 6.25 because proteins typically contain 16%
nitrogen. Not all nitrogen-containing compounds are true proteins. These
are called nonprotein nitrogen (NPN) sources. Many of these NPN compounds
can have their nitrogen converted to microbial protein in the rumen under
proper conditions. Generally, NPN sources are not used well as protein
when cattle are on high roughage rations or have high protein requirements,
such as young cattle with high rates of growth. True protein sources should
be used in these cases.
Energy is not actually a nutrient.
It is contained in nutrients such as carbohydrates, fats, etc. For practical
purposes energy will be considered a nutrient. There are several methods
of measuring feed energy values. Some of these are digestible energy, net
energy for maintenance and gain and total digestible nutrients. Total digestible
nutrients (TDN) is the value most commonly used in simple ration balancing.
Minerals are compounds needed
to regulate many metabolic functions in the body. They may be classed as
macro or trace minerals depending on the amounts needed. Examples of macro
minerals are calcium and phosporus. Iron, zinc and copper are examples
of trace minerals.
Other important nutrients are vitamins
and water. Rations are not normally balanced for these nutrients, but adequate
amounts must be provided for desired rates of growth. Water is particularly
important because feed intake decreases when water intake is not adequate.
Roughages are feeds that are
relatively high in fiber and low in energy. Hay, straw, cobs, cottonseed
hulls and corn stalks are examples of roughages.
Concentrates are feeds or mixtures
of feeds that are relatively low in fiber and provide energy as the primary
nutrient.
Formulating Rations
A systematic approach will help in
ration balancing. First, determine the nutrient requirements of the animal
being fed. This means determining the sex, size and production level of
the animal. With this information, nutrient requirements are available
from a table.
The next step is to determine the feeds
available for use. List their composition on a dry matter basis from a
composition table or a chemical analysis. Now the amounts of the feeds
necessary to balance the ration can be determined.
The following example will help in
understanding the first method used. The method illustrated is called a
Pearson Square. A ration will be balanced for a 500-pound medium-frame
steer calf with a desired gain of two pounds per day. The requirements
are shown in Table 1.
TABLE 1. -- Daily Nutrient Requirements (lbs.) For a 500-lb. Medium-Frame
Steer, ADG=2.01
| Dry Matter |
Protein |
TDN |
Calcium |
Phosphorus |
| lbs. |
lb. |
% |
lb. |
% |
lb. |
lb. |
| 13.1 |
1.49 |
11.4 |
8.85 |
67.5 |
.061 |
.031 |
11984 Nutrient Requirements of Beef Cattle
TABLE 2. -- Nutrient Composition Of Various Feedstuffs, Dry Matter
Basis1
| Feed |
% Dry Matter |
% TDN |
% Protein |
% Ca |
% P |
| Fescue Hay |
92 |
48 |
9.5 |
.3 |
.26 |
| Shelled Corn |
88 |
90 |
10.1 |
.02 |
.35 |
| Soybean Meal |
89 |
84 |
49.9 |
.33 |
.71 |
11984 Nutrient Requirements of Beef Cattle
Feeds available and their composition
are shown in Table 2. Energy or TDN will be the first nutrient balanced
for, 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 of
the square. Place the TDN values of fescue and shelled corn on the left
diagonals of the square and subtract across the diagonal, smallest number
from largest. Now, add the two numbers on the right hand side of the
square. These numbers mean that 22.5 parts of fescue and 19.5 parts of
corn will give a 67.5% TDN mixture.
Figure 1
There are 42 total parts in the ration. Divide the two numbers on the
right side of the square by the total to determine the preliminary percentage
of fescue and corn in the ration.
| Fescue |
22.5 ÷ 42 = .54 |
(54%) |
| Corn |
19.5 ÷ 42 = .46 |
(46%) |
The next step is to calculate the
percentage of crude protein in the fescue-shelled corn mixture and compare
with the animal's requirement. If the requirement is met or exceeded, the
ration is balanced. If the requirement is not met, protein supplementation
and additional balancing are needed.
Determine the percentage of crude protein
in the fescue-shelled corn mixture by multiplying the percentage of each
ingredient in the mix by its percentage of crude protein. Add the two resulting
values 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 corn
is 46% of the mix and contains 10.1% crude protein.
| Fescue |
.54 x |
9.5 = |
5.1% |
| Corn |
.46 x |
10.1 = |
4.6% |
|
|
|
9.7% |
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 deficiency
of 1.7% (11.4 - 9.7 = 1.7%) exists, and protein supplementation is needed.
Use the square method now to balance
the fescue-shelled corn mix and soybean meal for an 11.4% crude protein
mixture. Place 11.4 in the center and 9.7 and 49.9 on the left diagonals
and 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). Divide
each number on the right diagonal (38.5 and 1.7) by the total parts in
the ration (40.2) to determine the percentage of the mixture composed of
fescue and shelled corn (95.8%) and soybean meal (4.2%).
Fescue / shelled corn mix
Figure 2
Now, determine the pounds of dry
matter each feed ingredient contributes to the total. This is done by multiplying
the pounds of daily dry matter consumed (13.1) by the percentage each ingredient
contributes to the total. The protein supplement, in this case soybean
meal, must be calculated first.
Daily
| dry matter |
% Soybean |
Soybean meal |
| intake |
x meal |
= dry matter |
| 13.1 pounds |
x .042 |
= .55 pounds |
Now, determine the pounds of daily dry
matter available for fescue and shelled corn by subtracting the pounds
of protein supplement dry matter from the daily dry matter.
| Daily |
|
|
|
Pounds of |
| dry matter |
|
Soybean meal |
|
fescue-corn |
| intake |
- |
dry matter |
= |
dry matter |
| 13.1 pounds |
- |
.55 pounds |
= |
12.55 pounds |
There are 12.55 pounds of dry matter composed of the fescue-shelled
corn mixture.
To determine the individual pounds of
fescue and shelled corn, multiply the pounds of dry matter composed of
the fescue-shelled corn mixture by the percentage of fescue or shelled
corn determined in the first square. Subtract this value from the total
pounds of fescue-shelled corn dry matter to obtain the pounds of dry matter
of the second ingredient. In this example, fescue dry matter would be 6.77
pounds (12.55 lbs.x .54 = 6.77 lbs.), and shelled corn dry matter would
be 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 must
be converted to as-fed quantity so the farmer knows how much to actually
feed. This is done by dividing the pounds of dry matter by the percent
dry matter of the feed ingredient.
| Fescue |
= 6.77 |
÷ .92 |
= 7.35 pounds as fed |
| Shelled corn |
= 5.78 |
÷ .88 |
= 6.56 pounds as fed |
| Soybean Meal |
= .55 |
÷ .89 |
= .67 pounds as fed |
Thus, the daily ration for this
steer becomes 7.35 pounds of fescue, 6.56 pounds of shelled corn and .67
pounds of soybean meal.
Determine the calcium and phosphorus
supplied by each ingredient and compare to the daily requirements to decide
if a mineral supplement is needed. This is done by multiplying the dry
matter pounds of each feed in the ration by its calcium and phosphorus
content and adding the results. The results are compared to the animal's
needs; then an excess or deficiency can be determined.
Pounds of
| feed dry matter |
x |
% Ca |
= |
lbs. Ca |
| Fescue 6.77 |
x |
.003 |
= |
.020 |
| Shelled Corn 5.78 |
x |
.0002 |
= |
.001 |
| Soybean meal .55 |
x |
.0033 |
= |
.0018 |
|
|
Total |
|
.0228 |
|
|
|
|
|
| Pounds of |
| feed dry matter |
x |
% P |
= |
lbs. P |
| Fescue 6.77 |
x |
.0026 |
= |
.017 |
| Shelled Corn 5.78 |
x |
.0035 |
= |
.020 |
| Soybean Meal .55 |
x |
.0071 |
= |
.0039 |
|
|
Total |
|
.040 |
|
|
|
|
|
| Calcium need |
- |
intake |
= |
excess or deficiency |
| .061 |
- |
.0228 |
= |
.0382 deficiency |
|
|
|
|
|
| Phosphorus need |
- |
intake |
= |
excess or deficiency |
| .031 |
- |
.040 |
= |
.009 excess |
Phosphorus level of the ration is adequate,
but a deficiency of calcium exists. Minerals are generally supplied by
free-choice supplementation with commercial mineral supplements or home
mixtures.
A second method of ration balancing
may simply be termed trial-and-error formulation. In this method, a ration
is estimated, and the nutrient content calculated. These results are then
compared to the nutrient needs of the animal for which the ration is being
balanced. Deficiencies are corrected by changing proportions of feeds in
the rations or by substituting or adding ingredients.
The following example will help in
understanding. The same systematic approach is necessary. Knowledge of
animal nutrient requirements, feeds available and their nutrient composition
are still necessary. For this example, a 1000-pound cow in the last one-third
of gestation will be used. Her nutrient requirements are shown in Table
3. The same feeds as in the previous example will be used. Their nutrient
composition is shown in Table 2.
TABLE 3. -- Nutrient Requirements (lbs.) for a 1000-lb. Mature Cow,
Final Trimester Of Gestation1
| Dry Matter |
Protein |
TDN |
Calcium |
Phosphorus |
| lbs. |
lbs. |
% |
lbs. |
% |
lbs. |
% |
lbs. |
% |
| 19.6 |
1.6 |
8.2 |
10.5 |
53.6 |
.050 |
.26 |
.039 |
.20 |
11984 Nutrient Requirements of Beef Cattle
As hay is the primary source of nutrients
for most cows, this example will begin by assuming that all of the dry
matter being consumed is coming from fescue hay. This means the cow is
eating 21 pounds of actual fescue hay daily (lbs. of dry matter 19.6 divided
by the percentage of dry matter .92 equals 21 pounds).
Next, calculate the nutrients supplied
by fescue and compare them to the cow's need. The nutrients supplied are
determined by multiplying the pounds of dry matter of the feed consumed
by 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 pounds
of calcium and .05 pounds of phosphorus. A comparison with nutrient needs
shown in Table 3 reveals an energy deficiency of 1.1 pounds of TDN.
An addition of corn grain is necessary
for extra energy. We cannot simply add corn because the daily dry matter
intake would be exceeded and cattle might not be able to consume this amount.
Corn must be substituted for fescue. This means we will gain nutrients
from corn, but we will also lose nutrients from the fescue. The net effect
of 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 pounds
of TDN. The net effect of replacing one pound of fescue dry matter with
one 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 net
gain 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 dry
matter
.42 pounds TDN net gain
Now the ration is 17 pounds of fescue dry matter and 2.6 pounds of shelled
corn dry matter.
Calculate the nutrients supplied by
the substituted ration and compare to the cow's nutrient need. The comparison
is 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 to
pounds as fed as done for the previous ration. Divide pounds of dry matter
by percent dry matter. Thus the daily ration actually fed becomes 18.5
(17 ÷ .92) pounds of fescue and 2.95 (2.6 ÷ .88) pounds of
shelled corn.
Animals will gain more efficiently
and economically with a balanced ration. By using these guidelines, you
should be able to balance rations that will meet the needs of most farm
animals.
TABLE 4. -- Nutrient Content of the Substituted Ration and Comparison
with Requirements
| Feed |
Dry Matter lbs. |
TDN lbs. |
Crude Protein lbs. |
Calcium lbs. |
Phosphorus lbs. |
| Fescue |
17.0 |
8.16 |
1.61 |
.051 |
.044 |
| Shelled corn |
2.6 |
2.34 |
.26 |
-- |
.009 |
| Totals |
19.6 |
10.50 |
1.87 |
.051 |
.053 |
| Animal Requirements |
19.6 |
10.50 |
1.60 |
.050 |
.039 |
TABLE 5. -- Nutrient Requirements of Selected Groups of Beef Cattlea,b
| Body wt., lb |
Gain, lb |
Dry Daily Intake, lb |
Crude Protein Matter lb/day |
TDN
|
| D.M. |
% of lb/day |
D.M. |
% of Ca, % |
P, % |
| Heifer calves |
| 400 |
1.5 |
10.2 |
1.17 |
11.4 |
7.0 |
68.5 |
.45 |
.24 |
| 500 |
1.5 |
12.1 |
1.25 |
10.3 |
8.3 |
68.5 |
.38 |
.22 |
| 600 |
1.5 |
13.8 |
1.32 |
9.5 |
9.4 |
68.5 |
.32 |
.21 |
| Pregnant yearling heifers - last third of pregnancy |
| 750 |
1.4 |
16.6 |
1.5 |
8.9 |
10.0 |
59.9 |
.32 |
.21 |
| 850 |
0.9 |
17.6 |
1.4 |
8.2 |
9.6 |
54.5 |
.26 |
.20 |
| 950 |
0.9 |
19.0 |
1.5 |
8.0 |
10.3 |
54.1 |
.27 |
.20 |
| Dry pregnant mature cows - middle third of pregnancy |
| 1000 |
--- |
18.1 |
1.3 |
7.0 |
8.8 |
48.8 |
.18 |
.18 |
| 1100 |
--- |
19.5 |
1.4 |
7.0 |
9.5 |
48.8 |
.19 |
.19 |
| 1200 |
--- |
20.8 |
1.4 |
6.9 |
10.1 |
48.8 |
.19 |
.19 |
| .Dry pregnant mature cows - last third of pregnancy |
| 1000 |
0.9 |
19.6 |
1.6 |
8.2 |
10.5 |
53.6 |
.26 |
.21 |
| 1100 |
0.9 |
21.0 |
1.6 |
7.8 |
11.2 |
53.2 |
.26 |
.21 |
| 1200 |
0.9 |
22.3 |
1.7 |
7.8 |
11.8 |
52.9 |
.26 |
.21 |
| Two-year-old heifers nursing calves-first 3-4 months postpartum-10
lb milk/day |
| 800 |
0.5 |
17.6 |
1.9 |
10.8 |
11.2 |
63.8 |
.34 |
.24 |
| 900 |
0.5 |
19.2 |
2.0 |
10.4 |
12.0 |
62.7 |
.32 |
.23 |
| 1000 |
0.5 |
20.8 |
2.1 |
10.0 |
12.9 |
61.9 |
.31 |
.23 |
| Cows nursing calves - first 3-4 months postpartum-average
milking (10 lb/day) |
| 1000 |
--- |
20.2 |
2.0 |
9.6 |
11.5 |
56.6 |
.28 |
.22 |
| 1100 |
--- |
21.6 |
2.0 |
9.4 |
12.1 |
56.0 |
.27 |
.22 |
| 1200 |
--- |
23.0 |
2.1 |
9.3 |
12.8 |
55.5 |
.27 |
.22 |
| Cows nursing calves - first 3-4 months postpartum-superior
milking (20 lb/day) |
| 1000 |
--- |
20.6 |
2.5 |
12.3 |
13.8 |
67.0 |
.39 |
.27 |
| 1100 |
--- |
22.3 |
2.6 |
11.9 |
14.5 |
65.2 |
.38 |
.27 |
| 1200 |
--- |
23.8 |
2.7 |
11.5 |
15.2 |
63.7 |
.36 |
.26 |
| Bulls, maintenance and slow rate of growth (regain condition) |
| 1400 |
2.0 |
27.7 |
2.2 |
8.0 |
17.8 |
64.0 |
.25 |
.20 |
| 1600 |
1.0 |
29.7 |
2.2 |
7.3 |
16.6 |
55.8 |
.22 |
.19 |
| 1800 |
0.5 |
30.9 |
2.2 |
7.0 |
16.1 |
52.0 |
.20 |
.20 |
aVitamin A for
(1) pregnant heifers and cows-1270 IU per lb dry feed
(2) lactating cows and breeding bulls-1770 IU per lb dry feed
b Nutrient Requirements of Beef Cattle, National Research
Council, 1984.
TABLE 6. -- Composition of Commonly Used Feeds (dry matter basis)
NRC 1984.
| Feedstuff |
Dry Matter, % |
TDN, % |
CP, % |
Ca, % |
P, % |
| Alfalfa hay, midbloom |
90 |
58 |
17.0 |
1.41 |
.24 |
| Alfalfa hay, late bloom |
90 |
52 |
14.0 |
1.43 |
.25 |
| Barley grain |
88 |
84 |
13.5 |
.05 |
.38 |
| Bluegrass hay |
89 |
56 |
13.0 |
.33 |
.16 |
| Crimson clover hay |
87 |
57 |
18.4 |
1.40 |
.22 |
| Ladino clover hay |
90 |
60 |
22.0 |
1.35 |
.31 |
| Red clover hay |
89 |
55 |
16.0 |
1.53 |
.25 |
| Corn, yellow |
88 |
90 |
10.1 |
.02 |
.35 |
| Corn, yellow, high-moisture |
72 |
93 |
10.7 |
.02 |
.32 |
| Corn stover |
85 |
50 |
6.6 |
.57 |
.10 |
| Ground ear corn |
87 |
83 |
9.0 |
.07 |
.27 |
| Corn silage (few ears) |
29 |
62 |
8.4 |
.34 |
.19 |
| Corn silage (well-earred) |
33 |
70 |
8.1 |
.23 |
.22 |
| Corn, distillers grain (dehydrated) |
94 |
86 |
23.0 |
.11 |
.43 |
| Fescue hay, early veg. |
91 |
61 |
12.4 |
.51 |
.36 |
| Fescue hay, early bloom |
92 |
48 |
9.5 |
.30 |
.26 |
| Lespedeza hay, midbloom |
93 |
50 |
14.5 |
1.20 |
.25 |
| Molasses (syrup) |
78 |
79 |
8.5 |
.17 |
.03 |
| Oats |
89 |
77 |
13.3 |
.07 |
.38 |
| Orchardgrass hay, early bloom |
89 |
65 |
15.0 |
.27 |
.34 |
| Orchardgrass hay, late bloom |
91 |
54 |
8.4 |
.26 |
.30 |
| Sorghum stover |
88 |
54 |
5.2 |
.52 |
.13 |
| Sorghum grain (milo), 8-10 CP |
87 |
84 |
10.1 |
.04 |
.34 |
| Sorghum silage |
30 |
60 |
7.5 |
.35 |
.21 |
| Sorghum sudangrass hay |
91 |
56 |
8.0 |
.55 |
.30 |
| Sorghum johnsongrass hay |
89 |
53 |
9.5 |
.84 |
.28 |
| Soybean meal (44%) |
89 |
84 |
49.9 |
.33 |
.71 |
| Timothy hay, midbloom |
89 |
57 |
9.1 |
.48 |
.22 |
| Urea (45% nitrogen) |
99 |
0 |
281.0 |
0 |
0 |
| Wheat |
89 |
88 |
16.0 |
.04 |
.42 |
| Wheat hay |
88 |
58 |
8.5 |
.15 |
.20 |
| Wheat silage, full bloom |
25 |
59 |
8.1 |
.15 |
.20 |
| Wheat straw |
89 |
41 |
3.6 |
.18 |
.05 |
| Mineral Sources |
| Dicalcium phosphate |
97 |
--- |
--- |
22.0 |
19.3 |
| Ground limestone |
100 |
--- |
--- |
39.4 |
--- |
| Magnesium Oxide (56% Mg) |
98 |
--- |
--- |
3.1 |
--- |
| Steamed bone meal |
97 |
8.4 |
15 |
31.5 |
14.2 |
| Sodium tripolyphosphate |
96 |
--- |
--- |
--- |
25.0 |
