Sid Bosworth, Extension Associate Professor,
Department of Plant and Soil Science, University of Vermont email@example.com
The following tables and graphs summarize corn silage quality data from samples tested at the University of Vermont Agricultural Testing Lab. Table 1 gives an overall summary of 2005 compared to data collected at the same time period in 2004, while Table 2 on the next page compares quality data by dry matter content groupings (2005 samples only). In terms of fiber and energy (ADF, NDF and NEL, NFC and starch), overall corn silage quality was slightly better in 2005 than 2004 even though the range in values was somewhat similar.
Research has shown that, generally, the
best milk production by diary cows fed corn silage occurs when whole plant
dry matter content is between 30 and 35% or 65 to 70% moisture content
(Shaver et. al. 2004). In our summary of 2005 (Table 2), less than
half (44%) all 486 samples had dry matter levels between 30 and 35%.
Harvesting at a lower dm (<30%) content often results in increased seepage,
higher silage pH, lower dm intake and lower yields. About 32%
of the 2005 samples were in this category. Harvesting
too dry (> 40%) often results in poor packing, which can cause improper
fermentation and poor aerobic stability. Although NDF is lowest
in this group, which would imply a higher potential dm intake, research
has shown that the digestibility of this NDF would be lower than the NDF
harvested at an earlier maturity (Figure 5). Starch was highest in
this group, but again its digestibility is probably low especially if the
silage had not been processed (Figure 6).
Figure 5. Effect of maturity stage on 48 h NDF digestibility of corn silage. (from Hoffman et.al., 2003)
Figure 6. Effect of corn silage dry matter content on predicted apparent total tract starch digestibility. Top line - processed cornsilage and bottom line - unprocessed corn silage. (from Schwab et al., 2003)
Hoffman, P.C., K.M. Lundberg, L.M. Bauman and Randy D. Shaver. 2003. The Effect of Maturity on NDF Digestibility. Focus on Forage – Vol. 5: No. 15, Un. of Wisconsin Extension.
Shaver, Randy. 2004. Harvest and Storage of High-Quality Corn Silage for Dairy Cows. UN. of Wisconsin Extension. http://www.wisc.edu/dysci/uwex/nutritn/pubs/cshvst.PDF
Schwab, E. C., R. D. Shaver, J. G. Lauer, and J. G. Coors. 2003. Estimating silage energy value and milk yield to rank corn hybrids. J. Anim. Feed Sci. Technol. 109:1-18.
Forage Terms and Explanations Used by the University of Vermont Forage Testing Laboratory
This site is maintained by Sid.Bosworth@uvm.edu, Plant & Soil Science Department, University of Vermont.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont.University of Vermont Extension and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, sex, religion, age, disability, political beliefs, or marital or familial status