Lysine requirements of hybrid barrows (AG 1050 grandmother’s brothers), using 50 animals in a completely randomized block design with five dietary treatments (.50; .60; .70; .80 and .90% of total lysine), five replicates and two animals per experimental unit were estimated. Crystalline amino acids were added to keep amino acids levels according to the ideal protein profile. Quadratic effects of treatments on average daily gain and on feed conversion were observed. Linear effects of treatments on daily lysine intake, on 10th rib fat depth and on last rib fat depth were observed. No effects of lysine level on daily feed intake, P1 back fat thickness, P2 back fat thickness, loin depth, lean percentage, daily lean gain, carcass yield, carcass length, carcass length measured by Brazilian method, weights and sub primal cut yields were found. Barrows selected for high growth efficiency, from 96 to 120kg, required .61% of total lysine, which corresponds to approximately 22.74g/day of lysine intake.
swine; lysine; late finishing; performance; carcass
