Composition of Corn Silage Harvested in 2010

Dr. Maurice Eastridge, Extension Dairy Specialist, The Ohio State University

With the limited amount of rainfall, and to some extent the wide swings in temperature, the dry down of corn was very rapid this year. Yields of corn silage have been quite variable across the state and even within a farm and field, from moderate to quite good based on rainfall and ridges versus valleys in fields. There were a lot of problems with molds and mycotoxins in the 2009 crop, but there is much less of a problem with mold this year. Based on the data from the Dairy One Forage Laboratory (http://www.dairyone.com/) in Ithaca, NY, the corn silage harvested this year has higher starch and lower NDF concentrations compared to the 2009 crop (Table 1).  This likely reflects a higher ear to stalk ratio in the corn than for last year. At first glance, one would think that this means a higher energy value for the 2010 corn silage. However because of the rapid dry down, some farmers may have harvested the silage at higher DM than desired (harder kernels) and if a silage processor was not used, digestibility of the carbohydrates may be low. Digestibility should improve with advancing storage time. On the other hand, with proper stage of harvest and the higher starch (lower NDF) concentrations, rations need to be formulated with careful attention to physically effective fiber, particle size of the dry corn grain, and source of grain (dry versus high moisture versus steam flaked) that can affect ruminal pH and rate and extent of starch fermentation. The new crop corn silage should be analyzed, be allowed to stay in storage for at least several weeks if possible based on forage inventory, rations reformulated, and then observe cow performance (yield and composition of milk).

Table 1. Composition of corn silage harvested in 2010 versus 2009.¹

¹CV = Coefficient of variation [(standard deviation/average)*100], DM = dry matter, CP = crude protein,
ADF = acid detergent fiber, and NDF = neutral detergent fiber.