PSIX-37 Evaluation of reducing dietary crude protein concentrations coupled with increasing essential amino acids on growth performance in fattening pigs

Abstract

Abstract A body of evidence suggests that low-protein diets in swine have benefits in view of environmental stewardship and economic returns. The present study was performed to evaluate essential amino acid (EAA) supplementation in the diets with reducing crude protein (CP) concentrations on growth performance in fattening pigs. We hypothesized that a low-CP diet with elevated EAA concentrations would result in similar growth performance in fattening pigs compared with a normal CP diet. Eighty finishing pigs with initial body weight (BW) of 72.0 ± 5.34 kg were assigned in a randomized complete block design with 5 replicates to test 4 dietary treatments: 1) 15.5% CP with EAA concentration at 109% of NRC requirement (control); 2) 14.0% CP with EAA concentration at 111% of NRC requirement (EAA111); 3) 14.0% CP with EAA concentration at 113% of NRC requirement (EAA113); and 14.0% CP with EAA concentration at 115% of NRC requirement (EAA115). The diets were isocaloric, whereas crystalline amino acids, L-Lys, L-Met, L-Thr, L-Trp, and L-Val were added to the diets to achieve the varying levels of EAA in the treatments. The Lys-to-net energy ratio in the diets was maintained at 3.06, 3.12, 3.18, and 3.24 to the control, EAA111, EAA113, and EAA115, respectively. Dietary treatments did not affect final BW. Additionally, average daily gain, average daily feed intake, and feed conversion ratio (FCR) were similar across the treatments. On average, pigs fed the control and EAA111 numerically decreased FCR compared to those fed EAA113 and 115 (3.21 vs. 3.35, respectively; P = 0.46). Total feed cost throughout the experiment was $9.0/head lessen in EAA111 relative to the control; however, total feed costs to EAA113 and EAA115 were greater than the control. In summary, a low-CP diet with increased EAA supplementations did not have any negative impact on growth performance of fattening pigs.