Forage Quality and Feeding Management for Eastern Gamagrass in Wisconsin

Throughout Wisconsin, chopped straw often is purchased as forage and used within diets of dairy cattle to provide additional fiber, and maintain proper rumen function. For replacement heifers, straw is used commonly to dilute the energy density of the diet, limit voluntary intake, and prevent over-conditioning, especially within diets constructed for pregnant heifers weighing >1000 lbs. Unfortunately, the use of straw has several well-known problems. It often must be purchased, and then processed, before it can be blended properly within total mixed rations. Chopped straw also is sorted routinely by replacement heifers, which complicates its use in production situations where (inadequate) bunk space prevents all animals from eating simultaneously. Eastern gamagrass [Tripsacum dactyloides (L.) L.] (EGG) is a tall-growing, perennial warm-season grass, and a distant relative of corn (Bates et al., 1981). It retains many of the typical nutritional characteristics associated with perennial warm-season grasses that include: i) high concentrations of cell-wall components, such as NDF, even when harvested at very immature growth stages; ii) slower and/or poorer digestibility; and iii) greater proportions of crude protein (CP) that are associated with NDF (NDICP), and that bypass ruminal degradation. Recent research has shown that EGG haylage is non-sortable by heifers or cows, and could be a viable alternative to straw. This Focus on Forage report summarizes evaluations of the nutritional characteristics of EGG forages, and their use in diets of dairy heifers at the University of Wisconsin Marshfield Agricultural Research Station. What Concentrations of Fiber (NDF) Can Be Expected in Eastern Gamagrass Forages?