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Evaluation of the Effects of a Formaldehyde-based Feed Additive on Free Lysine
Feed has been identified as a potential biosecurity risk factor, and commercial swine operations are looking at steps to reduce their risk. Formaldehyde based feed additives (Sal CURB® ASF Liquid Antimicrobial, Kemin Industries, Des Moines, IA) have been identified as a potential step to mitigate risk. One of the potential drawbacks to formaldehyde is the denaturation and cross-linking of protein as this could limit the availability of protein to swine. An experiment was conducted to identify if free lysine is susceptible to damage from formaldehyde levels added to feed. The experiment was a 4 x 2 x 2 factorial design, and was analyzed as an ANOVA. Corn was mixed with 4 different levels of L-lysine HCl (0.00, 0.30, 0.45, and 0.60%) and was either not-treated or treated with Sal CURB (SC) with 3 replicate batches mixed per L-lysine HCl level. To simulate possible storage conditions, the corn and crystalline lysine mixture was stored for up to 20 d at room temperature and was analyzed for free lysine at 0, 10 and 20 d post-mix. At 0 d post-mix, SC negative treatments were analyzed for total lysine and crude protein to verify the correct amount of L-lysine HCl added. For this trial SC was applied at exaggerated levels between 3.72 to 3.85 kg/ton to increase the level of the formaldehyde challenge, and the application levels exceeded the regulated label requirements (3.0 kg/ton). Therefore, these study conditions reflect an experimental scenario. This resulted in a higher challenge to the free lysine in the mixture than a typical field application system. Average recovered free lysine level for the 0.00, 0.30, 0.45 and 0.60% L-lysine HCl treatments without SC were 0.00, 0.25, 0.38 and 0.50% respectively, and did not significantly change when SC was included (p=0.5009). There was no effect of d post-mix (p=0.1253) and no interaction between SC inclusion and L-lysine HCl level (p=0.6880). Even with Sal CURB levels being higher than the label requirements there were no effects of Sal CURB inclusion on free lysine.
Keywords: Formaldehyde, Biosecurity, Antimicrobial