Efficacy of supplemental liquid L-lysine for pigs in comparison to crystalline L-lysine HCl

Abstract Text: A study was conducted to test the effects of liquid L-Lys supplementation on growth performance in growing-finishing pigs compared with crystalline L-Lys HCl. A total of 126 pigs at 70 d of age (29.5 kg BW) in 42 pens were randomly allotted to 7 dietary treatments which were, CON: a control diet without supplemental Lys meeting 75% of SID Lys requirement, Level 1 diets with crystalline L-Lys HCl (C1) or liquid L-Lys (L1) meeting 82% of SID Lys requirement, Level 2 (C2 or L2) diets meeting 89% of SID-Lys requirement and Level 3 (C3 or L3) diets meeting 96% of SID Lys requirement. Each treatment had 6 pens (3 barrow and 3 gilt pens) with 3 pigs/pen. All 7 diets were formulated to contain nutrients meeting the requirements suggested by NRC (2012) except for SID Lys. Pigs were fed experimental diets for 9 wk based on 3 phases until 90 kg BW (30 to 45, 45 to 75, and 75 to 90 kg BW, respectively). All experimental diets were pelleted. Body weight and feed disappearance were measured to calculate ADG, ADFI, and G:F. Data were analyzed using the MIXED procedure in SAS. A mutilinear regression analysis was used to evaluate the relative bioavailability of liquid L-Lys to crystalline L-Lys HCl. Increasing Lys from 75 to 96% of SID Lys requirement improved (P < 0.05) ADG from 0.83 to 1.00 kg/d and G:F from 0.384 to 0.430 without affecting ADFI. Forms of Lys (crystalline vs. liquid) did not affect performance of pigs. Rates of increases in ADG and G:F of pigs fed diets with liquid L-Lys was not different (P = 0.803 and 0.336) from that of pigs (39.4 vs. 37.0 g/g daily intake of supplemental Met and 0.00828 vs. 0.00696/g daily intake of supplemental Met) fed diets with crystalline L-Lys HCl. This study demonstrates that efficacy of liquid L-Lys is not different from that of crystalline L-Lys HCl for performance of pigs from 30 to 90 kg. 

Keywords: growth performance, liquid lysine, L-lysine HCl