Forage Analysis of Wheat, Sorghum, and Corn Cropping Systems.

In 2008 Indiana corn production for silage was 2,200,000 Tons, and production is increasing annually. Silage provides feed of consistent quality and supply year round to livestock, most prevalently beef or dairy cattle.  Quality of ensiled feed is principally determined by the crop ensiled, its maturity at harvest, and the conditions under which the plant matter is ensiled.  The four stages of ensiling (aerobic, fermentation, stable, and feedout) are most efficient in a quickly-filled, airtight silo.  This project identifies the silage quality of samples ensiled in mino silos for 90 days at 68% moisture: silage corn, silage sorghum, grain sorghum, and sweet sorghum grown in Lafayette, Indiana in a wheat-based cropping system.  Forage crops were planted on three dates: May 13, June 12, and June 27. Growing forage crops following wheat allows for diversified production and may optimize economic yield.  In this experiment, sweet sorghum was the highest yielding forage crop by tonnage, producing 112.5 and 110 T/ac freshweight for each the middle and late planting dates. Silage quality is quantified by the relative amounts of soluble fibers, volatile fatty acids, lignin and cellulose.  Neutral Detergent Fiber (NDF) quantifies the cell contents and is only partially digestible; we found that the sweet sorghum planted at the two latter dates had the lowest overall NDF (45 and 46), while silage sorghum planted at the same dates had the highest NDF levels (55 and 56). Acid Detergent Fiber (ADF) levels optimally are low for high quality feeds because high ADF represents cell wall content which is undigestable for animals, and will reduce feed intake.  This study shows that the sweet sorghums from the latter two dates are the lowest for ADF (26 and 26) and the silage sorghums are the highest (30 and 32).  Butyric acid is deleterious, resulting from a side reaction that dilutes useful lactic acid and should be minimized, and all samples here tested reflected 0.00 butyric acid content. The most concise index for silage quality is pH, with more acidic being desirable. All of the silage in this experiment was below 4.3 pH, indicating that each crop sample would be considered 'good quality'. This data is preliminary, the first year of a three year study.