132 The Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance and Carcass Characteristics of 11- to 133-kg Late-Nursery-to-Finish Pigs Sired by PIC 800 Boars

Abstract

Abstract Our objective was to determine the effects of increasing standardized ileal digestible (SID) lysine (Lys) levels on growth performance and carcass characteristics of late-nursery-to-finish pigs sired by PIC 800 boars. Barrows and gilts [n = 1,00; PIC800×Camborough, initial body weight (BW) = 10.9 ± 0.39 kg] were used in a 142-d growth trial with 40 mixed sex pens, 10 pens per treatment, and 25 pigs per pen. At the beginning of the trial, pens were blocked by BW and randomly allotted to one of four treatments (overall dietary SID Lys level as 87, 95, 102, or 110% of PIC SID Lys recommendations) in a randomized complete block design. Diets were corn-soybean meal (SBM)-based, and treatments were achieved through the inclusion of SBM with adjustments of corn and choice white grease. Diets were fed in 7 phases (11-17, 17-34, 34-44, 44-57, 57-77, 77-95, and 95-133 kg) and formulated to be iso-caloric across treatments for each phase. Within each phase, only the diets of the least and greatest SID Lys levels were manufactured, and the diets of intermediate SID Lys levels were blended by the automatic feeding system in the research facility. Growth performance data were analyzed using the GLIMMIX procedure in SAS (Version 9.4, SAS Institute, Inc., Cary, NC) and considered pen as the experimental unit. The statistical model considered fixed effects of SID Lys levels and random effects of the block. Mortality and removals were also analyzed using the GLIMMIX procedure and specified a binomial distribution. All data are reported as least square means and considered statistically significant at P < 0.05 and marginally significant at P < 0.10. Increasing overall dietary SID Lys levels reduced overall average daily feed intake (linear, P = 0.045) and increased overall gain-to-feed ratio (linear, P = 0.002), but there was no evidence for a difference across treatments for overall average daily gain (P > 0.10) or overall removal and mortality rate (Table 1; P >0.10). Pigs fed overall SID Lys level as 102% of PIC recommendation had significantly greater carcass yield compared with those fed 95 or 110% (P < 0.05), with the pigs fed 87% being intermediate. Increasing overall dietary SID Lys levels reduced backfat depth (linear, P< 0.001) and increased lean yield (linear, P = 0.012), but there was no evidence for a difference among treatments for loin depth (P > 0.10). In conclusion, increasing overall dietary SID Lys level beyond PIC recommendations through increasing SBM levels resulted in improved feed efficiency, backfat depth, and lean yield of 11 to 133 kg pigs sired by PIC 800 boars.