Corn Silage Trials
Introduction
Michigan State University’s Department of Crop and Soil Sciences conducts hybrid corn silage trials each year in cooperation with MSU Extension, seed corn companies, and farmers.
Seed companies are invited to enter hybrids in the trials. A fee is charged to cover expenses.
Company names used in association with hybrid designations refer to the hybrid. In the index, numbers in parentheses following the hybrid refer to the table(s) or zone(s) in which each hybrid appears.
Methods
Two or three trial locations were planted in each of four maturity zones (see trial map; data from the trial locations in zones 2 and 3 are combined). Maturity zones are based on the average number of growing degree units available during the growing season as reported in long-term weather records. Hybrids entered in a zone were tested in each trial location within that zone. Entries for zones 1 and 2-3 are divided into two-maturity groups (early and late) based on maturity ratings provided by the seed companies. Experimental design, data acquisition, analysis of variance, and data summarization were facilitated by AGROBASE Generation I I™ (Agronomix Software, Inc., Winnipeg, Canada). The experimental design is a randomized complete block with four replications. Hybrid performance is reported as the adjusted mean of four plots.
Variety trials were conducted in farmer’s fields. All hybrids in a location were treated with the same management practices, e.g., fertilizers, seeding rate, date of planting, weed control, etc. Four-row plots were used at all locations. The two center rows were harvested for yield. Plots were 22-feet long with 30-inch row spacing. In the field, hybrids were identified only by plot number to assure unbiased comparisons. Both early and late silage trials in Branch County were irrigated.
Stand counts were conducted in June. Plots with stand counts higher than the desired population were thinned at this time. The desired population rates are listed in the Silage Agronomic Table. Plots were harvested mechanically and weighed with electronic scales mounted on the chopper.
A composite sub-sample was collected from each plot. The freshly chopped sub-samples (fodder plus grain) were weighed, oven dried, and then weighed again to determine the percent dry matter. The samples were then ground to pass through a 1.0 mm screen before silage quality analysis was completed.
The results shown are the average of four replications grown in close proximity to each other. Two or more plots of the same hybrid in the same field may produce somewhat different results because of uncontrolled variability in the soil and other environmental factors. Replication and randomization of the entries are two methods used to account for this variation. Because these methods do not eliminate all variables, the magnitude of difference necessary for statistical significance has been calculated for Green and Dry tones per acre, Dry Matter, and the quality components. The value calculated as the “least significant difference” or “LSD” is the amount that an individual hybrid would have to differ from another hybrid in the same test to be considered statistically significantly different from that hybrid. The CV, or coefficient of variation, is indicative of a trial’s precision. Trials with low levels of error variation have lower CV values.
Silage Quality
Silage quality data was determined using Near Infrared Spectral (NIR) analysis on fresh dried samples (samples are not ensiled). NIR analysis involves irradiating the ground sample with light in the near infrared range (1100 to 2500 nm). The illuminated sample absorbs light energy proportionally to specific chemical and physical properties. The reflected energy is measured and correlated statistically with established forage quality levels. Results of the four quality traits analyzed are presented in the quality tables. Data is provided for individual locations and averaged over multiple locations. The four quality traits reported are:
- IVD=(in vitro) digestible dry matter. This is a measure of forage
digestibility.
- ADF=acid detergent fiber. Acid detergent fiber represents the less
digestible portion of the corn silage and includes cellulose, lignin
and heat damaged proteins. ADF is closely related to the digestibility
of forages. Corn silage with a low ADF value is more digestible than
silage with a high ADF value. More mature plant material will generally
have a higher ADF content. A low ADF content is desirable.
- NDF=neutral detergent fiber. This is a measure of the fiber content
of the corn forage. Forages with high NDF levels have lower energy than
forages with low NDF. NDF is also a measure of potential forage intake.
When NDF levels are high the potential forage intake of animals is decreased.
Low NDF content is desirable.
- CP=crude protein. Forages are generally supplemented with a high
protein additive such as soybean meal to increase the protein content
of ruminant diets. Corn hybrids with high protein levels require less
supplementation and therefore result in lower feed costs. High protein
content is desirable.
- STRCH=Starch. Starch from the grain, along with the digestibility of the fiber, comprises the majority of the energy in corn silage.
MILK2000
New for 2003 is a calculation that estimates MK/T (milk per ton) and
MK/A (milk per acre) using the MILK2000 equation (UW-Madison Dairy Science
Department). MILK2000 estimates the dry matter intake using the NDF and
CWD (Cell Wall Digestibility) parameters of the sample. MILK2000 assumes
the weight of the cow is 1350 lb. and that it consumes a 30 percent NDF
diet. Using National Research Council (NRC, 1989) energy requirements,
the estimated intake of energy from corn silage is converted to milk per
ton. Milk per acre is then calculated using the estimated values for milk
per ton and dry matter yield per acre.
Corn Silage