158 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of Grow-Finish Pigs That Were Sired by PIC 800 Boars

Abstract

Abstract A total of 1,092 pigs (PIC 800 × Camborough) were used to investigate the effects of increasing dietary standardized ileal digestible (SID) Lys on growth performance in 4 experiments covering body weight ranges of 25-45 kg (Exp. 1), 45-73 kg (Exp. 2), 74-91 kg (Exp. 3), and 98-120 kg (Exp. 4). Pigs were placed in 1 room and divided into 2 groups with 42 pens/group and 13 pigs/pen (6 or 7 gilts and 7 or 6 barrows, balanced among treatments). Group 1 was used in Exp. 1 and 3; group 2 was used in Exp. 2 and 4. At the beginning of each trial, on-trial pens were blocked by body weight and randomly allotted to one of 6 treatments (85.0, 90.0, 95.0, 100.0, 107.5, or 115.0% of PIC SID Lys recommendations) in a randomized complete block design. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. In Exp. 2 to 4, the competing nonlinear models did not fit the data or improve the fitness compared with the linear models. Greater SID Lys linearly increased (P < 0.05) average daily gain in Exp. 1 and 3 (Table 1). Increasing SID Lys tended to increase gain to feed ratio (G:F; quadratic, P < 0.10) in Exp. 1, and broken-line linear and broken-line quadratic models estimated the maximum G:F at 99.9 and 98.5% SID Lys, respectively. In Exp. 2 and 3, increasing SID Lys also increased G:F (linear, P < 0.10). Growth performance did not differ among treatments in Exp. 4. Results indicated that the optimum SID Lys concentration for 25 to 45 kg PIC 800 pigs was between 98.5 and 99.9% of PIC SID Lys recommendations. More research is needed to validate the optimum SID Lys concentrations for pigs above 45 kg.