1. Animal Science Dep.; Federal Univ. of Viçosa; P.H. Rolfs Avenue Viçosa Minas Gerais Brazil 36570-000
2. Center for Subtropical Agroforestry; School of Forest Resources and Conservation, P.O. Box 110410, Univ. of Florida; Gainesville FL 32611
3. Soil and Water Science Dep., P.O. Box 110510; Univ. of Florida; Gainesville FL 32611