In Exp. 1, 2 diets were used in a 2 x 2 factorial design providing 50 or 60% SID Ile:Lys in combination with 57 or 70% SID Val:Lys. The Ile content of the diet did not affect performance. The ADFI and ADG were respectively 15 and 20% lower in piglets receiving diets with 57% SID Val:Lys compared with those receiving 70% SID Val:Lys. In Exp. 2, a control diet was formulated to provide 48% SID Ile:Lys. Four other diets were formulated by supplementing the basal diet with 1 of 2 sources of L-Ile differing in degree of purity to obtain 52 and 56% SID Ile:Lys in the diet. Level and source of L-Ile supplementation did not affect performance. To exclude a possible interaction between Ile and Lys, 4 diets were used in Exp. 3 in a 2x2 factorial design providing 1.00 or 1.15% SID Lys combined with 48 or 60% SID Ile:Lys. The ADG and F:G were affected by Lys supply (8 and 6% higher for piglets receiving 1.15% SID Lys) but not by Ile supply. Experiment 4 was carried out to test the effect of L-Ile supplementation using diets differing in BCAA content. Two protein sources (spray-dried blood cells and corn gluten meal) and 2 levels of Ile were used (50 and 65% SID Ile:Lys) in a 2x2 factorial arrangement. The SID Val:Lys and Leu:Lys contents were respectively 105 and 167% for diets containing spray-dried blood cells, and 70 and 180% for the diets containing corn gluten meal.
Neither protein source nor Ile level affected performance in piglets. These studies indicated that the SID Ile:Lys requirement may not be greater than 50% in cereal-based diets.
J van Milgen, R Barea, L Brossard, N Le Floc’h, D Melchior, and Y Primot, 2010. Journal of Animal Science, 87 (E-Suppl. 3):55.