1. USDA-ARS, U.S. Dairy Forage Research Center; 1925 Linden Dr. West Madison WI 53706-1108
2. Dep. of Agronomy; University of Wisconsin; Madison WI 53706-1597
3. USDA-ARS, Marshfield Agric. Res. Stn.; 8396 Yellowstone Dr. Marshfield WI 54449
4. Research partially supported by the University of Wisconsin College of Agricultural and Life Sciences. Use of trade or brand names does not imply an endorsement by the USDA-ARS or University of Wisconsin to the exclusion of any other product