Feeding Corn to Beef Cattle
AS-1238, December 2002
Greg Lardy, Extension Beef Cattle Specialist
Corn is commonly used as a feed grain in beef cattle diets throughout the United States. However, in many parts of North Dakota and other northern-tier states, feeding corn is less common. With the availability and improvement of shorter season corn varieties, corn production in North Dakota doubled from 1995 to 2001. In 2001, 81 million bushels of corn were produced, with producers in every county harvesting corn for feed grain.
Feeding Value of Corn
Compared to other feed grains, corn is lower in protein and
slightly higher in energy (Table 1). Corn contains approximately 70%
starch on a dry matter basis. Other important fractions in the
corn kernel include protein, fiber, and minerals.
Table 1. Nutrient content of various feed grains (NRC, 1996).
-----------------------------------------------------------------
Corn Barley Wheat Oats Sorghum
-----------------------------------------------------------------
TDN, % 90 88 88 77 82
NEm, Mcal/lb 1.02 0.94 0.99 0.84 0.91
NEg, Mcal/lb 0.70 0.64 0.68 0.55 0.61
CP, % 9.8 13.2 14.2 13.6 12.6
Escape Protein, % of CP 55 27 23 17 57
NDF, % 10.8 18.1 11.8 29.3 16.1
ADF, % 3.3 5.8 4.2 14.0 6.4
-----------------------------------------------------------------
The protein content of corn is approximately 55 to 60% escape or bypass protein. Escape protein is protein which is not fermented or degraded by the ruminal microorganisms, but is digested and absorbed by the animal in the small intestine. The remaining 40 to 45% of the protein in corn is rumen degradable protein. Rumen degradable protein is required by the ruminal microorganisms for use in growth and protein synthesis. Most research with corn indicates substantial benefit to providing rumen degradable protein in diets containing corn. Backgrounding or finishing diets containing high levels of corn require supplemental rumen degradable protein in the form of non-protein nitrogen (urea or biuret), natural protein sources such as sunflower meal, canola meal, or soybean meal, or a combination of non-protein nitrogen and natural protein.
Like all cereal grains, corn is low in calcium and relatively high in phosphorus (Table 2). Diets containing high levels of corn should include a supplemental calcium source such as limestone to prevent urinary calculi. The recommended calcium to phosphorus ratio in backgrounding and feedlot diets is a minimum of 2:1 (2 parts calcium to 1 part phosphorus).
Table 3 lists the nutrient content of corn harvested, stored, or processed by different methods. In general, different harvest, storage, and processing conditions do not result in large differences in nutrient content. The advantages and disadvantages of the different harvest, storage, and processing methods are discussed in detail later in this bulletin.
Table 2. Mineral content of major feed grains (NRC, 1996). ---------------------------------------------------------- Corn Barley Wheat Oats Sorghum ---------------------------------------------------------- Calcium, % 0.03 0.05 0.05 0.01 0.04 Phosphorus, % 0.32 0.35 0.44 0.41 0.34 Potassium, % 0.44 0.57 0.40 0.51 0.44 Magnesium, % 0.12 0.12 0.13 0.16 0.17 Sodium, % 0.01 0.01 0.01 0.02 0.01 Sulfur, % 0.11 0.15 0.14 0.21 0.14 Copper, ppm 2.5 5.3 6.5 8.6 4.7 Iron, ppm 54.5 59.5 45.1 94.1 80.8 Manganese, ppm 7.9 18.3 36.6 40.3 15.4 Selenium, ppm 0.14 - 0.05 0.24 0.46 Zinc, ppm 24.2 13.0 38.1 40.8 0.99 Cobalt, ppm - 0.35 - 0.06 - Molybdenum, ppm 0.60 1.16 0.12 1.70 - ----------------------------------------------------------
Table 3. Nutrient content of corn using different harvest, storage, or processing methods. ------------------------------------------------------------------------- Escape Dry TDN, NEm, NEg, Protein, Corn Type Matter % Mcal/lb Mcal/lb CP, % % of CP ------------------------------------------------------------------------- Dry Rolled Corn 86 90 1.02 0.70 9.8 60 Ear Corn 87 83 0.92 0.62 9.0 60 Steam Flaked Corn 82 94 1.06 0.73 10.0 45 High Moisture Corn 75 90 1.02 0.70 10.0 40 High Moisture Ear Corn 75 83 0.92 0.62 8.7 40 High Moisture Snapped Corn 74 81 0.90 0.59 8.8 40 ------------------------------------------------------------------------- Table adapted from Stock, R., R. Grant, and T. Klopfenstein. 1995. Average composition of feeds used in Nebraska. G91-1048-A. University of Nebraska.
Use of Corn in Rations for Beef Cattle
Corn can be used in many different types of backgrounding and finishing diets and it can serve as a supplement in forage-based diets for beef cows. However, corn is relatively low in protein and high in starch, which can negatively affect forage utilization, especially in diets based on lower quality forages. Consequently, corn grain should be used in forage-based diets at relatively low levels (less than 0.4% of body weight), in forage-based diets that have adequate crude protein (greater than 9% crude protein), or in combination with protein supplements.
Corn can serve as the sole
grain source in backgrounding
and finishing diets. Depending
on desired cattle performance,
the level of corn can be varied to supply additional energy in the
diet of growing and finishing cattle. However, supplemental protein
is needed in most corn-based backgrounding and finishing
diets, because of corn's low crude protein content.
Processing Corn
Even though corn can be fed whole with satisfactory results, cracking or rolling prior to feeding will increase digestibility by 5 to 10%. In most instances, grinding or rolling corn will not markedly improve average daily gain, but proper processing will improve feed conversion efficiency. As the proportion of corn in the diet increases, the benefits of processing also increase, because corn is supplying a greater portion of the energy. When corn is fed whole, the animal must process the corn by mastication (chewing). Rolling or cracking corn for use in a mixed ration may facilitate better mixing.
Corn can also be steam flaked. Steam flaking increases the energy availability 7 to 15%, but is typically not cost effective due to the substantial capital investment required and the relatively high price of natural gas in North Dakota.
Figure 1 shows the relative rates of fermentation for various corn processing methods. Fine grinding corn should be avoided in beef cattle diets since fine ground corn ferments quickly in the rumen. At high levels, this can lead to digestive disturbances, acidosis, and founder.
Figure 1. Effect of corn processing on relative rates of ruminal
starch digestion. Adapted from Stock and Britton (1993).
Effect of Corn Bushel Weight on Cattle Performance
Most research with light test weight corn indicates that it has
similar feeding value to higher test weight grain. Data from the University
of Nebraska indicates light test weight corn (46 to 48 pounds per bushel)
has similar feeding value compared to normal test weight corn (55 to
56 pounds per bushel). Research conducted at South Dakota State
University indicates that the net energy value of low test weight corn may be
slightly higher than normal test weight corn.
High Moisture Corn
Corn can be harvested wet and stored as high moisture corn. For corn to be used in this manner, it should be harvested at 22 to 28% moisture for optimum storage. High moisture corn is similar in energy and protein content to dry corn and offers several harvest advantages:
- Yields are typically increased due to less ear drop in the field.
- High moisture corn allows for an earlier corn harvest, avoiding difficulties associated with adverse weather.
- No drying costs are encountered.
Producers should also realize that high moisture corn also has some disadvantages compared to dry corn:
- Marketing alternatives are limited. High moisture corn which is ground or rolled will only be marketable through livestock.
- High moisture corn may require additional storage and processing equipment.
- Improperly ensiled high moisture corn will result in excessive spoilage and storage losses.
High moisture corn tends to ferment faster and require better
bunk management compared to dry corn. High moisture corn must be stored
in an airtight silo (bunker, silage bags, or oxygen-limiting structure).
For optimum storage and utilization, it should be processed (ground or
rolled) prior to storage. Grinding or rolling and subsequent packing of the
corn facilitates oxygen exclusion in the silo.
Price Considerations
Price comparisons for corn, barley, and oats on a cost per pound of crude protein and a cost per pound of total digestible nitrogen (TDN) basis are found in Table 4. Corn is typically priced competitively with barley on a cost per pound of TDN (or other measures of energy) basis. However, because of corn's relatively low protein content, the price per pound of crude protein for corn is typically higher than barley. Oats are generally more expensive on either a price per pound of TDN or protein basis compared to corn. As a general rule, corn should be used in rations as a cost effective source of energy but should not be purchased in situations where additional protein may be required since it is typically not priced competitively with other sources of protein.
When pricing corn, producers should take into account differences in moisture level, particularly with high moisture corn. Dry corn is typically traded at 15% moisture. High moisture corn can range from 22 to 28% moisture, which necessitates adjustment to a constant moisture necessary.
Table 4. Price comparison for various feed grains. ---------------------------------------------------------------------- -------------- Price Per Bushel -------------- Corn $1.50 $1.75 $2.00 $2.25 $2.50 $2.75 ---------------------------------------------------------------------- Cost per pound of CP $0.310 $0.363 $0.414 $0.466 $0.518 $0.570 Cost per pound of TDN $0.034 $0.040 $0.045 $0.051 $0.056 $0.062 ---------------------------------------------------------------------- -------------- Price Per Bushel -------------- Barley $1.25 $1.50 $1.75 $2.00 $2.25 $2.50 ---------------------------------------------------------------------- Cost per pound of CP $0.224 $0.269 $0.314 $0.359 $0.403 $0.448 Cost per pound of TDN $0.034 $0.040 $0.047 $0.054 $0.061 $0.067 ---------------------------------------------------------------------- -------------- Price Per Bushel -------------- Oats $1.00 $1.25 $1.50 $1.75 $2.00 $2.25 Cost per pound of CP $0.261 $0.326 $0.392 $0.457 $0.522 $0.587 Cost per pound of TDN $0.046 $0.058 $0.069 $0.081 $0.092 $0.104 ---------------------------------------------------------------------- Assumes 56 pound bushel for corn, 48 pound bushel for barley, and 32 pound bushel for oats. Crude protein and TDN contents can be found in Table 1. Assumes DM content of 88% (12% moisture).
Immature and Frost Damaged Corn
In some cases, due to late planting or early frost, corn may need to be harvested before it is mature. Nutrient content of immature corn can be considerably different than mature corn. Table 5 compares the nutrient content of corn at various stages of maturity. In addition, harvesting may be difficult. Immature corn can be harvested as ear or snapped corn after it is dry, or it may be harvested wet and stored in a silo structure as earlage.
Frost damaged corn is generally lower in test weight
than normal corn. However, feeding value is generally not
markedly reduced. Frost damaged corn should be analyzed for
nutrient content prior to feeding.
Table 5. Nutrient content of corn harvested at various stages of maturity. -------------------------------------------------------- Early Early Mid Nutrient Milk Dough Dent Mature -------------------------------------------------------- Crude Protein, % 16.6 12.5 10.7 10.9 Starch, % 47.4 55.0 58.7 63.7 Gross Energy, Kcal/lb 2073 2064 2086 2081 Bushel Weight, lb 35 47 55 58 -------------------------------------------------------- Adapted from Feeding High Moisture Corn, G74-100, University of Nebraska.
Summary
Corn is a useful feed ingredient. It is high in energy but relatively low in protein compared to other feed grains. For optimum dietary utilization, corn should be processed by rolling, cracking, or coarsely grinding prior to feeding. The decision to process corn should be based on efficiencies gained from processing compared to the cost of processing.
AS-1238, December 2002
See www.ag.ndsu.nodak.edu for
additional information.
