Effects of Standardized Ileal Digestible Lysine Level on Growth Performance in 230 to 285 lb DNA Finishing Pigs

Abstract

The objective of this study was to estimate the SID Lys requirement for growth and feed efficiency of 230- to 285-lb DNA finishing pigs. A total of 679 barrows and gilts (600 × 241, DNA; initial BW of 228.8 ± 2.9 lb) were used in two separate studies lasting 21- and 28-d, respectively. Pens of pigs were blocked by BW and randomly allotted to 1 of 6 dietary treatments with 8 to 10 pigs per pen in a randomized complete block design. A similar number of barrows and gilts were placed in each pen. Dietary treatments were corn-soybean meal-based and formulated to 0.43, 0.50, 0.57, 0.64, 0.71, and 0.79% SID Lys, with 12 replications for the 0.43, 0.50, 0.57, 0.71, and 0.79% SID Lys treatments, and 11 replications for the 0.64% SID Lys treatment. Increasing SID Lys increased (linear, P = 0.043) ADG, and improved (quadratic, P = 0.020) feed efficiency, resulting in pigs fed the diet containing 0.71% SID Lys having the greatest final BW and most optimum F/G. At high and low ingredient and pig prices, increasing SID Lys increased (quadratic, P = 0.004) IOFC. The broken-line linear model to maximize ADG predicted that there was no further improvement past 0.64% SID Lys. For F/G, the broken-line linear model predicted that there was no further improvement past 0.59% SID Lys. At high ingredient and pig prices, the quadratic polynomial model for IOFC predicted maximum economic return at 0.64% SID Lys. Additionally, at low ingredient and pig prices, the quadratic polynomial model for IOFC predicted maximum economic return at 0.62% SID Lys. In summary, the optimal SID Lys level for DNA finishing pigs from 230- to 285-lb depends upon the response criteria, with growth performance maximized between 0.59 to 0.64% SID Lys. Economic responses were maximized between 0.62% SID Lys and 0.64% SID Lys.