1. Wageningen University & Research, P.O. Box 338, 6700 AH Wageningen, the Netherlands.
2. Division of Livestock Sciences, Department of Sustainable Agricultural System, University of Natural Resources and Life Sciences, Vienna, Austria.
3. Animal Production and Health Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Vienna, Austria.
4. Faculty of Agriculture, University of Peradeniya, Peradeniya 20400, Sri Lanka.