135 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of PIC 337 × Camborough Commercial Pigs that were Sired by High Index Boars

Abstract

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible lysine levels on the growth performance of PIC 337 × Camborough commercial pigs that were sired by high-index boars. A total of 2,200 barrows and gilts (PIC 337 × Camborough) were used in six experiments covering body weight ranges of 11-25 kg (Exp.1), 26-46 kg (Exp.2), 45-66 kg (Exp.3), 63-85 kg (Exp.4), 86-110 kg (Exp.5), and 108-134 kg (Exp.6). Pigs were placed in two rooms with 45 pens in Room 1 and 43 pens in Room 2, and there were 25 pigs/pen (12 or 13 gilts and 13 or 12 barrows) for both rooms. Room 1 was used in Exp. 1, 3, and 5; Room 2 was used in Exp. 2, 4, and 6. At the beginning of each trial, on-test pens were blocked by body weight and randomly allotted to one of five treatments (90, 100, 105, 110, or 120% of PIC SID Lys recommendations for Exp.1 to Exp. 5; whereas 80, 90, 100, 110, or 120% of PIC SID Lys recommendations for Exp. 6) in a randomized complete block design. Off-test pens were fed a common wash-out diet between trials, and common diets were formulated to meet PIC nutrient requirements according to the specific weight range. Data were analyzed using generalized linear mixed model with pen as the experimental unit in R Studio (Version 3.5.2, R Core Team; Vienna, Austria). Dietary SID Lys levels were included as fixed effects, and weight block was included as random effects in the model. All data are reported as least square means and considered statistically significant at P < 0.05 and marginally significant at P < 0.10. Increasing SID Lys improved average daily gain (ADG; linear, P = 0.003) and gain-to-feed ratio (G:F; quadratic, P = 0.007) in Exp.1; improved ADG (quadratic, P = 0.045) in Exp.4; improved ADG (quadratic, P = 0.009) and G:F (quadratic, P = 0.002) in Exp.5; and improved ADG (linear, P = 0.037) and G:F (linear, P = 0.030) in Exp.6 (Table 1). However, there was no evidence for difference among treatments on growth performance in Exp.2 and 3. With increasing dietary SID Lys levels, gram of SID Lys per kilogram of bodyweight gain increased in a quadratic manner in Exp.1 (P = 0.025) and 5 (P = 0.002); and increased in a linear manner in Exp.2, 3, 4, and 6 (P < 0.001). In conclusion, increasing dietary SID Lys levels improved the growth performance of PIC 337 × Camborough commercial pigs sired by high-index boars when the bodyweight was below 25 kg or beyond 63 kg.