2007 Ohio-Michigan Silage Test

Rich Minyo, Peter Thomison, Keith Dysinger, and William Widdicombe

In recent years, requests for information on corn hybrid silage quality and yields from producers and seed company representatives has been increasing. In 2007, we conducted a joint trial with Michigan State University (MSU) adding one Ohio silage location to Michigan's two southern (Zone 1) silage locations. The Ohio test site was located in our Northwest Region at Hoytville (Wood County) The two MSU sites are located in Branch and Lenawee counties which are on the Ohio/Michigan state line. The test results from the three locations are treated as one region. The plots were planted with 4 row air type planters and maintained by each respective state utilizing standard production practices. The center 2 rows were harvested with MSU's self propelled forage harvester. Silage tests were harvested uniformly as close to half milk line as possible. Near Infrared Reflectance (NIR) Quality Analysis was performed by MSU using their current procedures. Silage results present the percent dry matter of each hybrid plus green weight and dry weight as tons per acre. Other data presented include percent stand, the percentage of in vitro digestible dry matter, acid detergent fiber, neutral detergent fiber, crude protein and starch. Milk production in pounds per ton and pounds per acre are estimated using MILK2000.

Methods

Testing procedures (randomization, replication, planting rates, etc.) for silage evaluation are the same as those utilized for the grain trials. Plots were four rows wide, and the center two rows were harvested for yield and quality.

Silage plots were harvested with a two-row self-propelled forage harvester. Electronic scales mounted on the chopper measured plot weights. Total plot weight is used to calculate green tons per acre (GT/A). Sub samples were collected (fodder plus grain), weighed, oven dried until weight loss was zero, then weighed again to determine the percent dry matter (%DM). Dry tons per acre (DT/A) is calculated using GT/A multiplied by %DM. The samples were ground using a 1.0 mm screen before conducting quality analysis using NIR (near infrared reflectance).


Corn Silage Information 2007

Silage Analysis

All silage tables provide silage quality data as determined by NIR analysis on freshly dried samples. Data is provided for individual locations and also averaged over multiple locations. Near infrared spectral analysis involves irradiating the ground sample with light in the near infrared spectrum (1,100 to 2,500 nm). The illuminated sample absorbs light proportional to specific chemical and physical properties. The reflected energy is measured and correlated statistically with established forage quality levels. Results of the five quality traits analyzed are presented in the quality tables. The six quality traits 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 forage, containing cellulose, lignin and heat damaged protein. ADF is closely related to the digestibility of forages. Lower ADF implies the forage is more digestible. More mature plant material will contain higher ADF concentrations. A low concentration of ADF is desirable.
   
• NDF=neutral detergent fiber. This is a measure of the fiber content of the corn forage. It is less digestible than non-fiber constituents of the forage. Forages with high NDF levels have lower energy. NDF is also a measure of potential forage intake. High NDF levels decrease the potential forage intake. Low NDF content is desirable.
   
• NDFD=neutral detergent fiber digestability. The portion of neutral detergent fiber digested by animals at a specified level of feed intake. High NDFD is desirable.
   
• CP=crude protein. Forages are generally supplemented with high protein concentrates 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 digestible component of the fiber, accounts for the majority of the energy in corn silage.
  

A calculation using the MILK2000 equation (UW Madison Dairy Science Department) estimates MK/T (milk per ton) and MK/A (milk per acre). 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 1,350 lbs. 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.