Investigating the Relationship Between Corn Silage Fiber Digestibility and Rainfall, Growing Degree Days, Soil Type, and Nutrient Application.

Corn silage (Maize) neutral detergent fiber (aNDFom) and digestibility (uNDFdom) are key qualities of the forage that influence the potential animal performance from the feed. In 2014 Cornell University introduced the undigestible fiber system (uNDFom). This system uses 3 time points, 30 h, 120h, and 240h analyzed on an organic matter (om) basis to determine the rate of digestion and amount of undigestible fiber in a forage. In the fall of 2015 and 2016, the relationship of rainfall, growing degree days (GDD50), and soil type on aNDFom and uNDFdom measured at 30 h, 120 h, and 240 h were evaluated on corn silage harvested in NY. Five fresh corn silage samples were taken from four different fields at three different farms in NY during the 2015 and 2016 harvest (N=120). Samples were analyzed for DM, aNDFom, uNDFdom30, uNDFdom120, uNDFdom240, and K at a commercial laboratory. Farms are located in Saratoga County NY, Cayuga County NY, and Livingston County NY. Farm records of daily rainfall, daily temperature, GDD50, planting dates, corn hybrid, harvest dates, soil type and nutrient applications from manure and fertilizer were collected from each farm. In 2015, total rainfall (planting to harvest) and cumulative GDD50 were correlated to decreased uNDFdom30 (r=-0.44, p<0.001) and uNDFdom240 (r=-0.27, p<0.05). Temperature effect (cumulative GDD) on uNDFdom30 begins with the temperatures the plant is exposed to in May (r=-0.68, p<0.001). This effect was greater in June (r=-0.72, p<0.001). There was a strong relationship of soil type to aNDFdom30, aNDFom120, and aNDF0m240 where soils more prone to being wet had lower digestibility (r=-0.56 to -0.78, p<0.001). Higher cumulative rainfall or rainfall in specific months decreased aNDFom digestibility. Additional data relating aNDFom digestibility to environmental and soil characteristics could result in improved water management systems and potentially altering timing for planting and harvest.