PSIII-18 - Effect of Increasing L-Lysine-HCl and Amino Acid Ratios on Performance of Finishing Pigs from 109 to 129 kg

Abstract: A total of 1,789 pigs (PIC; 337×1050; initial BW 108.9 ± 1.14 kg) were used to determine the effects of increasing L-Lys-HCl and AA ratios on performance of late finishing pigs fed corn-soybean meal diets without DDGS. The study used 2 groups of pigs and each study lasted 18 and 27 d, respectively. Pigs were housed in mixed gender pens with 20 to 25 pigs/pen and 19 replications/treatment (10 and 9 replications/group, respectively). Pens of pigs were blocked by BW and randomly allotted to 1 of 4 dietary treatments. Treatment diets were formulated to 0.70% digestible Lys and consisted of low, medium, or high levels of feed-grade AA and moderate or high AA ratios relative to Lys. Low, medium and high feed-grade AA treatments had increased L-Lys-HCl (0.15, 0.30 and 0.39%) replacing soybean meal to achieve CP levels of 13.6, 12.0, and 11.0. Minimum AA:Lys ratios were 53% Ile, 128% Leu, 58% Met&Cys, 66% Thr, 18.5% Trp, 68% Val, and 34% His in Moderate AA ratio diets and 60% Ile, 128% Leu, 60% Met&Cys, 70% Thr, 21.2% Trp, 72% Val, and 33% His for the high AA ratio treatment. Overall, there was a marginally significant increase in ADFI (quadratic, P = 0.097) observed in pigs fed medium feed-grade AA and moderate AA ratios. Treatment diets had no effect on ADG or G:F. At the end of group 2, carcass data was collected with no differences (P > 0.10) observed for HCW, carcass yield, backfat depth, loin depth or percentage lean. In summary, differing levels of feed-grade AA and AA ratios used in this study did not impact growth performance or carcass characteristics of late finishing pigs with the exception of a marginally significant increase in ADFI.