[1] Univ Manitoba, Dept Anim Sci, Winnipeg, MB R3T 2N2, Canada
[2] Univ Guelph, Dept Anim & Poultry Sci, Ctr Nutr Modelling, Guelph, ON N1G 2W1, Canada
[3] Univ Leon, Dept Anim Prod, E-24071 Leon, Spain
[4] Ctr Energia Nucl Agr, Anim Nutr Lab, Piracicaba, SP, Brazil