Conclusions
Linear-breakpoint analysis estimated the optimum SID Thr to Lys ratio as 0.68, 0.67 and 0.61 whereas curvilinear-plateau
analysis estimated the optimum SID Thr to Lys ratio as 0.73, 0.70 and 0.65 for ADG, FCR and SUN, respectively. Taking
an average of these values, we conclude that the optimum SID Thr to Lys ratio for 22–50 kg pigs fed low CP protein diets
supplemented with CAA is 0.70 to maximize ADG, 0.68 to optimize FCR and 0.63 to minimize SUN. Further research should
be conducted to determine whether or not the optimum SID Thr to Lys ratio is affected by dietary CP level.