1. South Dakota State Univ. Dep. of Animal and Range Sci. Box 2170 Brookings SD 57007
2. USDA‐ARS 344 Keim Hall, P.O. Box 830937 Lincoln NE 68583
3. Agronomy and Horticulture Dep. 279 Plant Sci., P.O. Box 830915 Lincoln NE 68583
4. Biometry Dep. 103 Miller Hall, Univ. of Nebraska Lincoln NE 68583