1. Dept. of Animal Science, Federal Univ. of Lavras; Campus Universitário; Caixa Postal 3037 37200-000 Lavras Minas Gerais Brazil
2. NSW Dept. of Primary Industries; Centre for Red Meat and Sheep Development; Cowra NSW 2794 Australia
3. NSW Dept. of Primary Industries; Elizabeth Macarthur Agricultural Inst; Menangle NSW 2568 Australia