feed intake was recorded daily, and diet samples were taken for analysis at weekly intervals (Garnsworthy et al.,2008a). to calculate digestible undegradable Leu concentrations, values for Leu in rumen escape protein were taken from Robinson (1998a,b,c) for all dietary ingredients except lupins.for lupins, Leu content (8.1% of CP) was measured in residuesafter 12h or rumen incubation in nylon bags