William H. Miner Agricultural Research Institute
Corn harvest is mostly completed although a significant number of farms in the Northeast and upper Midwest are facing later harvest of possibly immature or frost-damaged corn silage. Corn development has been delayed and so the risk of frost damage and the need to harvest immature corn silage has increased. Depending on the planting date and type of silo, projected harvest dates run well into October for some parts of the U.S. and Canada.
Nutritional Value of Immature Corn Silage
Immature corn silage will typically be higher in crude protein, NDF, and sugar content, but lower in starch than normal corn silage. Because dry matter content is often lower, the risk of poor fermentation is higher and the resulting silage may cause reduced dry matter intake. The energy value of immature corn silage ranges from 80 to 95% of normal corn silage. The reduction in energy content of slightly immature corn is not as great as you might expect because, although the NDF content of the whole plant is higher, the stalk fiber is less lignified and more digestible. Since many factors influence the nutrient composition of immature or frosted corn silage, an actual analysis of your specific corn silage is needed. Wet chemistry analysis may be better than NIR because calibrations for normal corn silage may not fit well with immature silages. You should discuss this issue with the forage testing lab that you use to determine whether their NIR analysis accurately predicts the nutrient profile of immature or frost damaged corn silage. In order to obtain the most accurate estimate of the silage’s true energy and feeding value, be sure to analyze the silage for CP, NDF and NDF digestibility, starch and starch digestibility in addition to the usual values reported on a typical forage analysis. Knowing the total fermentable carbohydrate content of your corn silage is critical for ration formulation.
Feeding New Crop Corn Silage
Regardless of whether the 2014 crop was harvested at ideal maturity or less than ideal, most dairy farms will have two sources of corn silage to feed: last year’s carryover silage which has fully fermented and steeped plus new crop corn silage. Feeding immature and/or frost damaged new-crop corn silage adds yet another silage feeding challenge. Minimizing variations in herd productivity with changing sources of corn silage requires a good understanding of what happens to the nutritive value of silage with time in the silo. Corn silage is a dynamic feed – amount and digestibility of nutrients vary with storage time and our ration formulation strategies must accommodate these changes: Continue reading