Effect of Feeding Formaldehyde Treated Feed to Pigs Throughout the Growing Period on Amino Acid Utilization from Synthetic Lys or Protein Sources

A total of 1,113 pigs (36 ± 1.67 kg BW) were used in a 36-d study conducted as a RCBD (block =start body weight) in a commercial wean-to-finish facility. Pigs were randomly allocated to the following dietary treatments: Trt1) No feed disinfection/No synthetic Lys; Trt2) Feed disinfection (Sal CURB^®, Kemin)/No synthetic Lys; Trt3) No feed disinfection/Synthetic Lys inclusion; Trt4) Feed disinfection/Synthetic Lys; and Trt5) As Trt2 with 10% lower Lys level. For treatments 2 and 4, feed was disinfected by applying Sal CURB at 2.95 kg/metric ton of feed in the mixer. A two-phase feeding program was used, with phase changing on d 22 of study. Diets were based on established PIC recommendations and provided 3,300 kcal ME/kg. SID Lys levels were 1.03% (0.95% SID Lys for Trt5) and 0.91% (0.82% SID Lys for Trt5) for phases 1 and 2, respectively. Data collected included pen weights, feed intake, and animal removals. Data were analyzed using the PROC MIXED procedure of SAS with pen as the experimental unit and treatment as a fixed effect. Results were considered significant at P ≤ 0.05 and considered a trend at 0.05 < P ≤ 0.10. During dietary phase 1, there was no treatment effect for BW and ADG. Feeding disinfected feed affected (P < 0.05) G:F of pigs fed diets without synthetic Lys (0.592 vs 0.559, Trt1 vs. 2, respectively), but had no impact (P = 0.63) on diets with synthetic Lys (0.526 vs. 0.521, Trt3 vs. 4, respectively). During dietary phase 2, there were no differences or trends detected across treatments for any variable measured. For the overall 36-d study period, ADG (1.08, 1.07, 1.07 1.05, and 1.03 kg) and ADFI (2.10, 2.15, 2.17, 2.17, and 2.10 kg) was similar (P > 0.15) across treatments (Trt1 to 5, respectively). Overall G:F (0.510, 0.493, 0.490, 0.474, and 0.485) was negatively affected by the process of feed disinfection with or without inclusion of synthetic Lys in diets (Trt1 vs. 2, and 3 vs. 4). In addition, the combined G:F of treatments 2 and 4 (disinfected feed; 0.483) was no different than that of Trt5 (0.485). These results indicate that disinfecting feed with Sal CURB may have a negative effect on feed efficiency of pigs regardless of the level of synthetic Lys used in the diets.