... consumptionin sheep: y ¼ 0:09x þ 0:45 (R2¼ 0: 393 ). Data for cattle taken from Huntington and Tyrrell( 198 5); Reynolds et al. ( 198 6, 198 8a, 199 1b, 199 2a–c, 199 4a, 199 5, 199 8a,b, 199 9, 2000, 2001,2003a,b); ... from: Reynolds et al.( 198 8a, 199 2b, 199 4b, 2003a);Reynolds and Tyrrell ( 199 1);Krehbiel et al. ( 199 2); Casse et al.( 199 4); Taniguchi et al. ( 199 5).Huntington et al. ( 199 6);Lozano et al. (2000); ... Ferrell ( 199 5); Patil et al. ( 199 5, 199 6); Goetschet al. ( 199 7a–d); Park et al. ( 199 7); Lindsay (unpublished).Metabolism of the Portal-drained Viscera and Liver 3 19 Half (Judson and Leng, 197 3b;...