Field Crops 28.5-4
Corn Germplasms for Silage Uses
Joe Lauer, Corn Agronomist
Currently, there is much interest by producers and seed companies in evaluating
corn hybrid silage performance. Wisconsin is the largest corn silage producing state
in the U.S. Between 1989 and 1993, corn silage was grown on 570 000 to 950 000 acres,
which accounted for 15 to 28 percent of the total corn acreage in Wisconsin. In
the past, university and seed company agronomists have suggested that the best grain
hybrids were also superior hybrids for silage yield and quality. Most producers
grow corn for both grain and silage purposes with the final use decision being made
at harvest. High grain yield does not necessarily correlate with forage quality.
Most producers are aware that there is considerable genetic variation for nutrition
value among corn hybrids. Corn hybrid silage yield and quality differences can be
economically important to dairy and livestock operations.
Advantages of corn silage include: 1) a palatable forage with relatively consistent
quality and higher yields and energy content than most other forages, 2) requires
significantly less labor and machinery time than other harvested forages due to
only a single harvest activity, 3) cost per ton of dry matter also tends to be much
lower than for other harvested crops. Disadvantages include: 1) few established
markets for silage sales, 2) transportation costs are high so the crop must often
be fed near the farm where it is produced, 3) storage facilities tend to be more
expensive than those for dry hay, 4) where corn is not well adapted, the cost of
production may be too high to warrant corn silage production, 5) on erodible soils
corn silage production may be limited due to residue requirements in soil conservation
Corn silage is primarily an energy supplying forage with its nutritive value related
to digestibility and factors that affect digestibility such as intake and fiber.
Silage quality of dent corn has been reported to range from 54 to 86 percent dry
matter digestibility, 7 to 11 percent crude protein, 23 to 43 percent acid detergent
fiber, and 40 to 68 percent neutral detergent fiber. Whole plant dry matter yields
in Wisconsin have been as high as 11 ton per acre. The range in silage quality parameters
may be smaller than the range in yield for corn hybrids developed for specific environments.
The large range in digestibility and other silage quality parameters reported in
the literature can be attributed to hybrid differences in maturity, grain-to-stover
ratio, grain composition, stover composition, and methods of forage analysis.
Plant breeders have developed several types of corn differing in their silage characteristics.
These corn types may have silage quality advantages, but usually are poor performers
agronomically when compared to dent corn because of yield or standability deficiencies.
Desirable silage characteristics include 1) high dry matter yield, 2) high energy
content, 3) high intake, and 4) optimum dry matter content at harvest for acceptable
fermentation and storage. Corn silage is primarily an energy supplying feed, and
its nutritive value is related to digestibility and factors that affect digestibility.
Several types of corn are available from corn breeders that differ in their genetic
makeup and may affect silage characteristics (Table 1). These include brown-midrib,
waxy, sugar or grainless, sweet corn and high-oil corn. Usually these types of corn
are agronomically poor performers because of yield or lodging.
Table 1. Range in relative dry matter yield and forage quality characteristics of
dent corn and other corn germplasms.
Dry Matter Yield
ADF : NDF
relative to dent corn
23-43 : 40-68
21-39 : 37-65
--- : 45-50
--- : 51
20-26 : ---
22-37 : 41-57
--- : 40
29-37 : ---
--- : 65
--- : ---
--- : ---
Brown-midrib corn has reduced lignin levels in stalks and leaves compared to lignin
levels in normal corn plants. Since lignin is undigestible, brown-midrib corn plants
should be more digestible than normal corn plants. Increased digestibility is usually
found in the stover of brown-midrib types. However, animal performance in feeding
trials is inconsistent. Agronomic evaluations have shown slower growth rates, poor
early season vigor, increased lodging, delayed flowering, and poor grain yields.
Normal corn starch contains about 75 percent amylopectin starch and 25 percent amylose
starch. Waxy grain contains all amylopectin starch. Limited feeding trial data suggest
that waxy corn could equal, but not exceed, normal corn for forage quality. Waxy
corn is very similar to normal corn for agronomic characteristics.
Sweet corn is often available for ensiling as canning factory waste, stover, and
as whole plants. Canning factory waste consists of husks, cobs, and some ears. This
silage is usually lower in protein and energy than silage made from eared field
corn. On a dry matter basis, its nutritive value equals that of immature field corn.
Sweet corn stover left after removing the ears for the factory has more nutritive
value than stover from ripe field corn due to greater leafiness, and greener leaves
and stalks. Whole plant corn silage is made by allowing the plant to mature before
ensiling, and its feed value equals that of field corn with similar ear-stalk ratios.
A disadvantage of sweet corn is its slow grain dry down rate which means it must
be harvested later than field corn. This not only delays harvest and increases the
risk of spoilage, but reduces stover quality due to increased lignin and fiber concentrations.
High-oil corn has greater energy than normal corn because the calorie content of
oil is approximately 2.5 times as great as that of carbohydrates. Feeding trials
show greater dry matter intake, but lower digestibility than silage of normal corn.
Field yield losses have been associated with elevated oil levels.
Opaque-2 mutants of corn have elevated levels of lysine and tryptophan. General
nutritional value of this silage was similar to normal corn silage. Feeding trials
have shown no advantage for these genotypes over normal corn.
Regular dent corn hybrids will continue to be used for both grain and silage purposes
and will be the predominant germplasm source for many years to come. Breeding activity
by seed companies has led to development of dent corn hybrids with claims of improved
silage quality. Previous studies indicate that differences do exist for commercial
dent corn hybrids. These small differences might be economically significant.
No hybrids are screened routinely for silage quality by University hybrid evaluation
programs. Producers should select corn hybrids based on grain yield potential, standability,
and pest resistance. If the decision is made at planting to grow corn for silage,
then a slightly longer season hybrid (about 5 to 10 relative maturity units) should
be considered. Once a high performing corn hybrid is identified, the producer should
consult with the seed company representative for information on the relative quality
ranking of the hybrid among the hybrids being marketed within the company.
Andrew, S.M., J.H. Clark, and C.L. Davis. 1979. Feeding value of opaque-2 corn grain
silage for lactating dairy cows. J. Dairy Sci. 62:1619.
Atlin, G.W., and R.B. Hunter. 1984. Comparison of growth, forage yield and nutritional
quality of diploid and autotetraploid maize synthetics. Can. J. Plant Sci. 64:593.
Atwell, D.G., E.H. Jaster, K.J. Moore, and R.L. Fernando. 1988. Evaluation of high
oil corn and corn silage for lactating cows. J. Dairy Sci. 71:2689.
Barriere, Y., Y. Montalant, and A. Boyat. 1984. Etudes des teneurs en proteines
et des valeurs agronomiques de descendances de croisement mais X teosinte. Agronomie
Bowden, D.M., S. Freyman, and N.B. McLaughlin. 1973. Comparison of nutritive value
of silage from tillering and nontillering hybrid corn. Can. J. Plant Sci. 53:817.
Bowden, D.M., N.B. McLaughlin, and S. Freyman. 1975. Feeding value of silage from
a tillering and nontillering hybrid corn. Can. J. Plant Sci. 55:955.
Byers, J.H., K.A. Kenddall, and E.E. Ormiston. 1965. Feeding value of dwarf corn
silage compared to corn and hybrid sorghum silages. J. Dairy Sci. 48:203.
Colenbrander, V.F., V.L. Lechtenberg, and L.F. Bauman. 1973. Digestibility and feeding
value of brown midrib corn stover silage. J. Anim. Sci. 37:294.
Coors, J.G., P.R. Carter, and R.B. Hunter. 1994. Silage corn. In Specialty corns.
Dudley, J.W., and D.E. Alexander. 1969. Performance of advanced generations of autotetraploid
maize. Crop Sci. 9:613.
Francis, T.R., and G. Gendron. 1977. Population studies of multitillering versus
nontillering corn for silage in Eastern Canada. Can. J. Plant Sci. 57:312.
Frenchick, G.E., D.G. Johnson, J.M. murphy, and D.E. Otterby. 1976. Brown midrib
corn silage in dairy cattle rations. J. Dairy Sci. 59:2126.
Freyman, S., M.S. Kaldy, D.M. Bowden, and D.B. Wilson. 1973. Nutritive potential
of multitillering corn compared with nontillering corn for silage. J. Plant Sci.
Kurle, J.E., C.C. Shaefer, R.K. Crookston, R.H. Peterson, H. Chester-Jones, and
W.E. Lueschen. 1991. Popcorn, sweet corn, and sorghum as alternative silage crops.
J. Prod. Agric. 4:432.
Lee, M.H. and J.L. Brewbaker. 1984. Effects of brown midrib-3 on yields and yield
components of maize. Crop Sci. 24:105.
Major, D.J. 1977. Seasonal dry-weight distribution of single stalked and multitillered
corn hybrids grown at three population densitites in Southern Alberta. Can. J. Plant
Miller, J.E., and J.L. Geadelmann. 1983. Effect of the brown midrib-3 allele on
early vigor and growth rate of maize. Crop Sci. 23:510.
Muller, L.D., R.F. Barnes, L.F. Bauman, and V.F. Colenbrander. 1971. Variation in
lignin and other structural components of brown midrib mutants of maize. Crop Sci.
Muller, L.D., V.L. Lechtenberg, L.F. Bauman, R.F. Barnes, and C.L. Rhykerd. 1972.
In vivo evaluation of a brown midrib mutant of Zea mays L. J. Anim. Sci. 35:883.
Ramsey, D.S. 1963. Dwarf corn for silage. J. Dairy Sci. 46:366.
Rook, J.A., L.D. Muller, and D.B. Shank. 1977. Intake and digestibility of brown
midrib corn silage by lactating dairy cows. J. Dairy Sci. 60:1894.
Sommerfeldt, J.l., D.J. Schingoethe, and L.D. Muller. 1979. Brown-midrib corn silage
for lactating dairy cows. J. Dairy Sci. 62:1611.
Stallings, C.C., B.M. Donaldson, J.W. Thomas, and E.C. Rossman. 1982. In vivo evaluation
of brown midrib corn silage by sheep and lactating dairy cows. J. Dairy Sci. 65:1945.
Thomas, V.W., W.M. Benson, and T.W. Perry. 1975. Effect of normal vs. opaque-2 vs.
roasted normal corn and normal vs. opaque-2 corn silage for finishing beef cattle.
J. Anim. Sci. 41:641.
Tourbier, B. and D.A. Rohweder. 1983. Effect of stage of maturity, corn hybrid type,
and population on corn silage moisture and quality. Proc. Am. Forage Grasslnd Council,
Eau Claire, WI.
Tracy, W.F. and J.G. Coors. 1990. Agronomic performance of sugary-Braun2 maize,
a potential additive for high-protein silage production. Agron. J. 82:1.