1. CSIRO Livestock Industries, St. Lucia, Brisbane 4067, Queensland, Australia
2. University of New England, School of Rural Science and Agriculture, Armidale 2351, Australia
3. Faculty of Agriculture, Department of Animal Science, Adnan Menderes University, Aydin 09100, Turkey and
4. Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel