Impact of formaldehyde addition to spray-dried plasma on functional parameters and animal performance

Experimental objectives of this study were to determine effects of formaldehyde treatment on the chemical composition of spray-dried plasma (SDP) and to test the hypothesis that growth performance of pigs fed formaldehyde-treated diets containing SDP or diets containing formaldehyde-treated SDP is not reduced compared with pigs fed untreated control diets. Sal CURB ASF liquid antimicrobial and CURB RM Extra liquid mold inhibitor (Kemin Industries, Des Moines, IA) were applied on SDP at 0.1% or 0.3% to determine effects of the products on chemical and functional properties of SDP. Regardless of product, there were no changes in SDP for analyzed protein, ash, pH, or moisture concentration, but IgG concentration in SDP was decreased 8% and 24%, respectively, for 0.1% and 0.3% inclusion of Sal CURB or CURB RM. Two feeding studies using weaned pigs were conducted to determine effects of formaldehyde applied at 0.3% to SDP (experiment 1) or 0.3% to a complete diet containing 5% SDP (experiment 2). Experiment 1 pigs (n = 265) were weaned at 20 ± 2 d of age and allotted to five treatment groups. Experiment 2 pigs (n = 135) were weaned in two groups at 20 ± 2 d of age and allotted to three treatments groups. In experiment 1, the untreated control diet contained soy protein concentrate (SPC) and test diets contained 2.5% or 5.0% SDP without or with formaldehyde treatment. In experiment 2, formaldehyde was applied to a diet containing 5% SDP and an untreated SPC control diet and an untreated diet containing 5% SDP were also included in the experiment. In experiment 1, linear increases (P < 0.05) in average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) were observed as SDP was included in the diets and the relative bioavailability of formaldehyde-treated SDP was 62% (P = 0.018) if calculations were based on ADG and 15% (P = 0.031) if calculations were based on ADFI. In experiment 2, pigs fed the SDP diet untreated or treated with formaldehyde had increased (P < 0.05) final body weight, ADG, ADFI, and G:F compared with pigs fed the control diet. However, formaldehyde treatment of the plasma-containing diet did not affect pig growth performance compared with pigs fed the untreated SDP diet. In conclusion, formaldehyde treatment applied directly on SDP affects analyzed concentrations of IgG and reduces growth rate of pigs. Treating a complete diet containing 5% SDP with formaldehyde did not affect pig growth performance, and pigs fed diets containing SDP had improved growth performance than those fed the control diet without SDP.