Monday, December 9, 2013

Corn Silage Gets Better with Age & Attention to Detail

This article was originally written for and distributed to farmers and other members of the agricultural industry in western New York.

Leave Corn Silage in the Bunk
It is well-known that feeding “green” corn silage will result in lower milk production than “cooked” corn silage. This change in production is due primarily to the increases in starch and protein availability as the silage cures in the bunk or silo. Generally corn silage needs to be stored for a minimum of 3 weeks to complete the ensiling process. As corn silage sits in the bunk the availability of starch will generally increase up to 6 months of storage. However BMR varieties appear to buck the trend of conventional hybrids feeding poorly with little time in the bunker this year. My observations on farms in western NY that are feeding “green” BMR corn silage indicate little, if any, drop in milk production in 2013. Follow-up research is necessary to confirm if the BMR varieties are truly outperforming conventional varieties in wet years and coming out of the bunk “green,” but the initial observations are promising.

The Corn Silage Shake Down
A number of reports of poorly chopped and processed corn silage have come in from across western New York. Besides chemical analyses, using the Penn State Shaker Box and kernel processing scores to measure physical characteristics can help determine whether or not your corn silage was chopped and processed correctly. When corn silage has been chopped & processed properly most of the material will be in the middle screen of the Penn State Shaker Box, Table 1.

Table 1: Corn silage, haylage, and TMR particle size recommendations for lactating cows.

But there is an exception to these guidelines---Shredlage. A higher portion of the particles (~30%) will be in the Upper Sieve compared to lower percentages found in normal corn silage. No sorting has been observed by dairy cows fed Shredlage. Kernel processing scores are determined by drying corn silage, running it through a series of sieves (Figure 1), and ranking by the percentage of the starch (i.e. the kernels) that pass through the 4.75 mm screen, Table 2

Table 2. Kernel Processing Scores & Percentage of Samples

*Corn Silage Processing Score, 551 Samples, CVAS 2006 Crop Year

Most of the corn silage has room for improvement as less than 10% of all samples have optimal processing scores. Again Shredlage corn silage is the exception to the rule as most samples have received “Optimally Processed” rankings when analyzed for kernel processing scores. The reason why most scores are lower than desired is that adjustments are often not made to the chopping equipment during harvest. 

Figure 1. Kernel Processing Score Sieves

Whether you are chopping your own corn silage or rely on a custom operator the only way to know whether or not your silage is being chopped and/or processed correctly is to get out in the bunk and measure it as it’s starting to come in. While it is too late to change this year’s silage, you can run next year’s freshly chopped silage through the Penn State Shaker Box on farm when the first load comes in and send a sample off for kernel processing score analysis at most of the commercial labs. If nothing else, get out of the tractor and down into the bunk to have a closer look at your corn silage. Using these tools and your experience will help make the necessary adjustments to theoretical length of cut and processing roll settings in order to improve the physical characteristics of your corn silage in future years.

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