The University of Georgia
GAES Research Report Number 657
November 1998

Silage Tests Results

Selection of Corn Hybrids for Use as Silage

J. C. Johnson, Jr. and R. N. Gates

    The information presented in the following tables is intended to help producers select corn hybrids which produce large yields of high quality silage.  Consistently high yields over several locations and years reliably show a hybrid's ability to produce top yields.  Primary quality factors are the proportion of grain and the digestibility of the grain and non-grain portions of the hybrid.  Hybrids differ in the proportion of grain they produce.

    In the past it was accepted that a hybrid with the highest proportion of grain made the highest quality silage.  Research has shown that many times this is not true.  In-vitro dry matter digestibility (IVDMD) is a measure of the percentage of a feedstuff the animal can digest and utilize.  IVDMD values for grain are high and do not vary greatly among hybrids.  IVDMD values for the non-grain portion (fodder) of the corn plant are lower but much more variable among hybrids compared to the grain portion.  Thus, one hybrid with a lower proportion of grain could have high quality (digestibility) because the IVDMD of its fodder portion was much higher than another hybrid having a higher proportion of grain but a much lower IVDMD of its fodder portion.

    The yield and IVDMD of the whole plant (fodder and grain) should be considered when selecting a hybrid to produce silage.  Some dairy farmers may be tempted to sacrifice yield and use a hybrid with a very high proportion of grain to increase the digestibility (energy density) of the silage.  Feeding such high grain content silage plus the concentrate feeds usually fed can overload the rumen with starch and lead to serious acidosis and associated health problems plus abnormal composition of milk produced.  The most desirable silage hybrids for dairy cattle should produce top yields of highly digestible silage.  To obtain this high digestibility and maintain high silage intake and normal digestive function, emphasis should be directed to high digestibility of fodder with a lower proportion of grain rather than trying to obtain high digestibility by maximizing the proportion of grain.



Summary of Evaluations of Corn Hybrids for Silage
Blairsville, Calhoun, Griffin, and Tifton, Georgia, 1998

       Quality Factors1       

        IVDMD         

                Dry Matter Yield               
Company or Brand Name Hybrid
No.		 Maturity Class Fodder Grain Whole Plant2 Grain Portion Statewide Average Blairsville Calhoun Griffin Tifton
----------- % ----------- % -------------------- tons/acre -------------------
Short and Mid-Season
 
AgraTech ATX999 M 64.5 91.6 74.7 39 . . . . 11.2
Asgrow RX 938 M 57.6 92.2 73.7 46 . . . . 11.5
DeKalb DK 683 M 55.0 92.3 72.4 47 9.8 10.9 6.8 7.5 14.0
DeKalb DK 687 M 59.0 93.4 76.4 51 . . . . 12.3
DeKalb DK 706 M 57.8 91.5 73.2 45 . . . . 10.2
 
DeKalb DK 720S M 58.8 91.6 73.9 46 . . . . 11.4
NK N 8811 M 57.8 92.1 72.9 44 9.9 11.7 7.2 8.1 12.5
NK N 83-N5 M 54.9 92.5 73.4 49 . . . . 12.0
NK N 83-R7 M 57.3 92.9 76.0 52 . . . . 11.5
NK N73-N8 S 59.7 92.6 75.3 48 . . . . 11.5
 
Pioneer 31G20 M 57.4 91.8 72.5 44 9.6 11.5 6.0 8.0 12.9
Pioneer 3154 M 57.9 91.1 71.0 40 9.4 11.7 6.6 8.5 11.0
Terra TR 1186 M 57.3 92.4 75.7 53 8.6 10.0 6.7 7.4 10.2
 
Average 58.1 92.1 73.9 46 9.5 11.2 6.7 7.9 11.7
LSD at 10% Level 3.5 N.S.3 2.8 5 - 1.5
Std. Err. of Entry Mean 1.5 0.5 1.2 2 - 0.6
 
Full-Season
 
AgraTech 1177 F 55.0 82.6 63.9 32 . . . . 13.8
DeKalb DK 743 F 57.0 90.7 71.0 41 . . . . 12.4
Grabow 9006C F 57.3 82.7 67.6 41 . . . . 14.5
Greenwood 830 F 53.7 86.9 64.9 33 . . . . 12.0
Greenwood 835 F 53.7 86.6 66.5 39 . . . . 12.5
 
Greenwood 840 F 54.8 86.8 65.6 34 . . . . 12.0
Greenwood 845 F 54.5 86.4 65.9 36 . . . . 11.9
NK             McNair 508 F 56.8 81.2 64.6 32 . . . . 10.2
Pioneer 3085 F 55.3 87.0 68.8 43 9.0 10.0 5.8 8.2 12.1
Southland 1496135 F 50.8 83.1 62.3 35 . . . . 11.0
 
Southland SS-8136 F 56.3 87.1 68.1 38 8.8 11.5 6.5 7.7 9.7
 
Average 55.0 85.6 66.3 37 8.9 10.8 6.2 8.0 12.0
LSD at 10% Level N.S. 3.8 3.3 6 - N.S. 0.8 N.S. 1.7
Std. Err. of Entry Mean 1.7 1.6 1.4 3 - 0.6 0.3 0.3 0.7
1. Quality factors taken from the replicated silage trial at Tifton.
2. This variable is calculated to reflect the relative contribution of each component using the following     formula: whole plant IVDMD = fodder IVDMD X percent fodder + grain IVDMD X percent grain.
3. The F-test indicated no statistical differences at the alpha = .10 probability level; therefore, an LSD     value was not calculated.
Bolding indicates entries performing equally to highest performing entry within a column based on Fisher's protected LSD (P = 0.10).


Tifton, Georgia:

Evaluation of Corn Hybrids for Silage, 1998, Irrigated
Company or Brand Name Hybrid Name Maturity Class Forage Yield
Dry     Green		 Dry Matter Grain Portion 2-Year Average Dry Forage Yield
tons/acre % % tons/acre
Short and Mid-Season
 
DeKalb DK 683 M 14.0 33.7 41.5 47 12.6
Pioneer 31G20 M 12.9 30.6 42.1 44 .
NK N 8811 M 12.5 32.4 38.6 44 11.6
DeKalb DK 687 M 12.3 33.3 37.0 51 12.3
NK N 83-N5 M 12.0 28.1 42.7 49 .
 
NK N73-N8 S 11.5 29.8 38.7 48 11.3
Asgrow RX 938 M 11.5 32.7 35.1 46 11.7
NK N 83-R7 M 11.5 28.9 39.6 52 11.3
DeKalb DK 720S M 11.4 28.7 39.5 46 11.7
AgraTech ATX999 M 11.2 29.9 37.2 39 11.4
 
Pioneer 3154 M 11.0 26.6 41.1 40 11.7
Terra TR 1186 M 10.2 27.4 37.5 53 10.9
DeKalb DK 706 M 10.2 26.7 38.1 45 10.7
 
Average 11.71 29.9 39.1 46 11.6
LSD at 10% Level 1.5 3.4 3.3 5 N.S.2
Std. Err. of Entry Mean 0.6 1.4 1.4 2 0.4
 
Full-Season
 
Grabow 9006C F 14.5 34.4 42.0 41 .
AgraTech 1177 F 13.8 34.6 40.2 32 12.7
Greenwood 835 F 12.5 33.2 37.8 39 12.4
DeKalb DK 743 F 12.4 31.0 40.1 41 11.7
Pioneer 3085 F 12.1 33.6 36.1 43 11.4
 
Greenwood 830 F 12.0 31.0 38.5 33 .
Greenwood 840 F 12.0 32.0 37.4 34 .
Greenwood 845 F 11.9 33.1 36.0 36 .
Southland 1496135 F 11.0 29.2 37.9 35 .
NK McNair 508 F 10.2 27.2 37.4 32 10.4
 
Southland SS-8136 F 9.7 26.6 36.4 38 .
 
Average 12.03 31.4 38.2 37 11.7
LSD at 10% Level 1.7 3.3 N.S. 6 N.S.
Std. Err. of Entry Mean 0.7 1.4 1.6 3 0.4
1. CV = 10.5%, and df for EMS = 36.
2. The F-test indicated no statistical differences at the alpha = .10 probability level; therefore, an LSD     value was not calculated.
3. CV = 11.9%, and df for EMS = 30.
Bolding indicates entries yielding equal to highest yielding entry within a column based on Fisher's protected LSD (P = 0.10).
Planted: March 30, 1998.
Harvested: July 20, 1998.
Population: 31,600 plants/acre in 30" rows.
Soil Type: Tifton loamy sand.
Soil Test: P = High, K = Medium, and pH = 6.2.
Fertilization: 55 lb N, 110 lb P2O5, and 165 lb K2O/acre as preplant; 212 lb N and 20 lb S/acre as sidedress.
Previous Crop: Soybean.
Management: Subsoiled and rototilled; Sutan, Accent, Permit, and two cultivations used for weed control; Lorsban used for insect control; irrigated 10 inches.
 
Test conducted by A. E. Coy and M. Pippin.


Griffin, Georgia:

Evaluation of Corn Hybrids for Silage, 1998, Irrigated
Company or Brand Name Hybrid Name Maturity Class Forage Yield
Dry      Green		 Dry Matter Grain Portion 2-Year Average
Dry Forage Yield
tons/acre % % tons/acre
 
Pioneer 3154 M 8.5 16.8 50.4 50 9.1
Pioneer 3085 F 8.2 18.6 44.0 53 9.9
NK N 8811 M 8.1 17.3 47.6 55 9.4
Pioneer 31G20 M 8.0 16.1 49.6 52 .
Southland SS-8136 F 7.7 18.2 42.3 47 .
 
DeKalb DK 683 M 7.5 16.4 46.1 53 8.8
Terra TR 1186 M 7.4 16.0 46.0 53 8.3
 
Average 7.91 17.1 46.6 52 9.1
LSD at 10% Level N.S.2 1.7 3.6 4 N.S.
Std. Err. of Entry Mean 0.3 0.7 1.5 2 0.6
1. CV = 7.4%, and df for EMS = 18.
2. The F-test indicated no statistical differences at the alpha = .10 probability level; therefore, an LSD     value was not calculated.
Bolding indicates entries yielding equal to highest yielding entry within a column based on Fisher's protected LSD (P = 0.10).
Planted: April 6, 1998.
Harvested: August 20, 1998.
Population: 28,000 plants/acre in 30" rows.
Soil Type: Appling coarse sandy loam.
Soil Test: P = Medium, K = High, and pH = 6.7.
Fertilization: 49 lb N, 98 lb P2O5, and 147 lb K2O/acre as preplant; 200 lb N/acre as sidedress.
Previous Crop: Soybean.
Management: Moldboard plowed and rototilled; Aatrex and Lasso used for weed control; irrigated 12 inches.
 
Test conducted by J. L. Day.


Calhoun, Georgia:

Evaluation of Corn Hybrids for Silage, 1998, Irrigated
Company or Brand Name Hybrid
Name		 Maturity Class  Forage Yield 
Dry     Green		 Dry
Matter		 Grain Portion 2-Year Average
Dry Forage Yield
tons/acre % % tons/acre
 
NK N 8811 M 7.2 15.8 46.3 45 9.4
DeKalb DK 683 M 6.8 15.7 43.2 42 8.6
Terra TR 1186 M 6.7 14.4 46.4 52 8.3
Pioneer 3154 M 6.6 13.1 50.4 47 8.6
Southland SS-8136 F 6.5 15.0 43.5 46 .
 
Pioneer 31G20 M 6.0 10.9 54.8 48 .
Pioneer 3085 F 5.8 13.3 43.8 49 8.8
 
Average 6.51 14.0 46.9 47 8.7
LSD at 10% Level 0.8 2.2 5.3 N.S.2 N.S.
Std. Err. of Entry Mean 0.3 0.9 2.1 2 0.5
1. CV = 9.6%, and df for EMS = 18.
2. The F-test indicated no statistical differences at the alpha = .10 probability level; therefore, an LSD     value was not calculated.
Bolding indicates entries yielding equal to highest yielding entry within a column based on Fisher's protected LSD (P = 0.10).
Planted: April 27, 1998.
Harvested: August 27, 1998.
Population: 28,000 plants/acre in 30" rows.
Soil Type: Waynesboro loam.
Soil Test: P = High, K = Medium, and pH = 6.3.
Fertilization: 75 lb N, 90 lb P2O5, and 180 lb K2O/acre as preplant; 150 lb N/acre as sidedress.
Previous Crop: Cotton.
Management: Moldboard plowed and rototilled; Aatrex and Dual used for weed control; irrigated 3 inches.
 
Test conducted by J. L. Day, G. Rawls, and J. Stubbs.


Blairsville, Georgia:

Evaluation of Corn Hybrids for Silage, 1998, Nonirrigated
Company or Brand Name Hybrid
Name		 Maturity Class  Forage Yield 
Dry       Green		 Dry Matter Grain Portion 2-Year Average
Dry Forage Yield
tons/acre % % tons/acre
 
Pioneer 3154 M 11.7 20.8 56.5 56 11.8
NK N 8811 M 11.7 23.8 49.2 54 11.3
Pioneer 31G20 M 11.5 21.5 53.7 55 .
Southland SS-8136 F 11.5 23.9 47.9 52 .
DeKalb DK 683 M 10.9 21.2 51.5 52 10.7
 
Pioneer 3085 F 10.0 19.7 51.1 58 10.9
Terra TR 1186 M 10.0 19.6 51.1 55 9.5
 
Average 11.01 21.5 51.6 54 10.8
LSD at 10% Level N.S.2 2.8 2.4 N.S. N.S.
Std. Err. of Entry Mean 0.6 1.2 1.0 2 0.4
1. CV = 10.6%, and df for EMS = 9.
2. The F-test indicated no statistical differences at the alpha = .10 probability level; therefore, an     LSD value was not calculated.
Bolding indicates entries yielding equal to highest yielding entry within a column based on Fisher's protected LSD (P = 0.10).
Planted: May 14, 1998.
Harvested: October 2, 1998.
Population: 24,000 plants/acre in 30" rows.
Soil Type: Bradson clay loam.
Soil Test: P = High, K = Medium, and pH = 6.3.
Fertilization: 90 lb N, 90 lb P2O5, and 90 lb K2O/acre as preplant; 100 lb N/acre as sidedress.
Previous Crop: Soybean
Management: Moldboard plowed and disked; Aatrex, Bicep, and one cultivation used for weed control.
 
Test conducted by J. L. Day and H. D. Garrett.