1. Department of Poultry Science, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706
2. Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706
3. Tokyo Institute of Technology, O-Okayama, Meguro-ku, Tokyo, Japan 152
4. Tokyo College ofPharmacy, 1432-1 Horinouchi, Hachioji-shi, Tokyo, Japan