Feeding Corn Stover to Ruminants

By Maurice Eastridge, OSU Department of Animal Sciences. First published OSU Extension Beef Team Newsletter, issue #550. With the dry conditions this year in many areas of Ohio, the yield of hay has been reduced and corn silage yields are going to be quite variable based on planting time and geographic area.
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Therefore, forage supplies are going to be quite limited this year, and several areas have been already reporting unreasonably high hay prices. Obviously, ruminants must have forage in their diets to remain healthy. Also with the current hay and grain prices, overall feed costs are going to be elevated for quite some time. With these conditions, alternative forage sources are being considered, including the feeding of corn stover (corn plant after grain harvest). The composition of corn stover is provided in Table 1, and it is compared to the composition of corn grain, corn silage, and wheat straw. The grain and forage components of corn are low in protein, but they especially contribute energy to the diet and fiber for ruminal health. Because of the lower starch and higher fiber, corn stover provides less energy than corn grain or silage. The comparison of the composition of corn stover with wheat straw is made because wheat straw is sometimes fed at low concentrations (2 to 8% of dietary DM) to lactating dairy cattle as a source of effective fiber (fiber that stimulates rumination) and higher concentrations are sometimes fed to nonlactating, nongrowing ruminants. The price for wheat straw is often quite high and the supply often limited caused by the demand for its use as bedding and feed. When you consider that about 50% of the corn plant is stover and that at least 4 times more acres of corn are produced in Ohio compared to acres of wheat, the availability of corn stover is not limited. The composition of corn stover and wheat straw is somewhat similar and are similar in price values at the reported DM (Table 1), but at similar DM (e.g. 90%), corn stover is valued at about 5% more than wheat straw.

Some things that must be considered when feeding corn stover are:

  1. Animals can be pastured on a corn field harvested for grain, but their presence in the field must be limited initially because they will eat too much grain that was left in the field. A considerable amount of feed wastage also occurs with pasturing corn fields.
  2. Because of the low protein in corn stover and the limited intake that may occur, additional supplementation usually necessary, even for nonlactating, nongrowing animals.
  3. The feeding value of ammoniated corn stover is higher than for unammoniated stover. Ammoniated corn stalks (2 to 3% of DM; increase in CP by 6 to 8 percentage units) fed with 2 lb/day of grain supplement to 525 lb steers increased DM intake, DM digestibility, and N retention compared to unammoniated corn stalks fed with the same amount of supplement (Purdue University). Mature beef cows fed similar diets had higher DM intake and weight gain with ammouniated versus unammoniated corn stover.
  4. Because of the large particle size of corn stover, challenges may occur when adding stover to a total mixed ration because cows can readily sort thorough the TMR, leaving the corn stalks in the bunk and having lower fiber intake than anticipated. Therefore, reducing the particle size before or during mixing will be important in reducing the risks for sorting.
  5. The corn stover certainly can provide a considerable amount of energy and fiber as a forage source; however, very low inclusion rates in lactating cow diets can help to provide an effective fiber source (95% of the fiber in corn stover is regarded as effective fiber) and may also be used to reduce a small amount of starch from the ration. However, corn stover is not an effective replacement for grain, even if pelleted. For example, in an University of Illinois study reported this year, corn stover was treated with calcium oxide and water, mixed with distillers grains (3:1 corn stover:distillers grains), and then pelleted. Diets fed to lactating dairy cows containing 40% corn silage, 10% alfalfa silage, 5.5% soybean hulls, and either 0, 11, or 22% of the corn stover pellet to replace corn grain. As the amount of corn stover pellet increased, DM intake, milk yield, and milk protein percentage decreased. Thus, even with chemical processing and reduction to a small particle size, corn stover is not a replacement for corn grain as an energy source.

The supply of corn stover is plentiful and it should be evaluated as a source of forage in diets for ruminants during times of limited forage supply and when desiring to provide low amounts of additional effective fiber in diets for maintaining rumen health.

Table 1. Composition (DM basis) of corn-based feeds and wheat straw.
Item (1) Corn Grain Corn Silage Corn Stover Wheat Straw
DM % 88.1 35.1 85.0 90.0
CP % 9.4 8.8 5.0 4.8
TDN % 88.7 68.8 49.0 45.7
ME Mcal/lb 1.42 1.06 0.79 0.65
NEL Mcal/lb 0.93 0.66 0.49 0.37
NEm Mcal/lb 0.98 0.71 0.50 0.38
NEg Mcal/lb 0.67 0.44 0.19 0.13
NDF % 9.5 45.0 65.0 73.0
ADF % 3.4 28.1 42.4 49.4
Lignin % 0.9 2.6 10.0 8.8
Ash % 1.5 4.3 7.2 7.6

(1) DM = Dry matter, CP = crude protein, TDN = total digestible nutrients, ME = metabolizable energy, NEL = net energy for lactation, NEm= net energy for maintenance, NEg = net energy for gain, NDF = neutral detergent fiber, and ADF = acid detergent fiber.



September 2007

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