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Suggested structures, chop length and screen size for harvesting corn for silage   arrow

By: Dr. Tim L. Stanton, Extension Feedlot Specialist
Colorado State University, Dept Animal Sciences
Ft Collins, CO 80523-1171, 970/491-6905
tstanton@lamar.colostate.edu

I had several questions about harvesting drought stressed corn silage and thought more information about chop length and moisture level might be helpful. The following table lists guidelines for harvesting corn silage.

Table 1.
Suggested structures, chop length and screen size for harvesting corn for silage.
Dry matter moisture in standing crop Usual maturity Ideal structure for storage Optimum length of crop Screen size
70% or more Milk stage Stack, trench or bunker less than 10 ft deep 1/2 inch None needed
65% to 69% Early dough to hard dough Stack, trench or bunker, more than 10 ft deep, or upright silo 1/2 inch None needed
60% to 69% Well dented to mature Upright structures

or

trench or bunker more than 14 ft deep

3/8 inch

1/4 to 3/8 inch

2 ½ to 3-inch screen below knives

2 to 2 ½ inch screen below knives

50% to 59% Mature seed to one-half dry stalk Upright structures in very good condition of tightness 1/4 to 3/8 inch, sharp knives 2 to 2 ½ inch screen below knives
50% or less Half to completely dry stalk Gas-limiting structure 3/8 to 1/2 inch, sharp knives 2-inch screen below knives

It appears that there is little concern about the nutritional effects of fine chopping for growing and finishing beef cattle. Silage chopped less than 3/8 inch is satisfactory and gives equivalent gain and efficiency as that chopped at a 5/8 inch length, however, it takes more energy to harvest silage chopped at 3/8 inch than at 5/8 inch.