Nutritional evaluation of conventional, high protein, reduced fiber, and reduced phosphorus corn co-products for poultry

Abstract

The nutritional characteristics of conventional distillers dried grains with solubles (DDGS), corn fermented protein (CFP), high protein-DDGS (HP-DDGS), reduced fiber high protein-DDGS (RFHP-DDGS), and reduced phosphorus-DDGS (RP-DDGS) were evaluated. The precision-fed rooster assay was utilized to measure TMEn and standardized amino acid (AA) digestibility. Corn fermented protein contained an average of 56% CP (DM basis), which was higher than 32% CP for conventional DDGS. The CFP also contained a higher (P < 0.05) TMEn of 3,556 kcal/kg DM compared with 2,767 kcal/kg for conventional DDGS. Standardized AA digestibility of CFP was high and the mean digestibility of all AA ranged from 89% to 94% among samples. Digestible AA concentrations were increased substantially for CFP; for example, digestible Lys content was increased from 0.79% for conventional DDGS to 1.74% for CFP. High protein-DDGS contained 50.9% CP (DM basis) and the TMEn was 3,325 kcal/kg DM. The average standardized AA digestibility was high (88%) and digestible AA contents were increased compared with conventional DDGS. Reduced fiber high protein-DDGS contained 48% CP and the TMEn was 3,711 kcal/kg DM. The standardized AA digestibility of RFHP-DDGS and conventional DDGS was high, although some samples exhibited reduced Lys digestibility, and RFHP-DDGS contained higher concentrations of digestible AA compared with conventional DDGS. The RP-DDGS contained 0.39% total P compared with 0.86% total P for conventional DDGS (DM basis). Reduced P-DDGS also contained a larger ash and Ca content compared with conventional DDGS, and the TMEn was reduced (P < 0.05) to 2,840 kcal/kg from 3,428 kcal/kg DM. The standardized AA digestibility and digestible AA content were similar between RP-DDGS and conventional DDGS. Apparent ileal P digestibility determined in precision-fed chicks was reduced from 81% for conventional DDGS to 59% for RP-DDGS, and dietary Ca level had no effect on ileal P digestibility. In another experiment using precision-fed chicks, the apparent ileal P digestibility of conventional DDGS was found to decrease (P < 0.05) from 80% to 48% when the Ca:total P ratio was increased from 0.3 to 1.3. A similar effect was also observed using ad libitum-fed chicks; thus, when the dietary Ca:total P ratio increased from 1.3 to 2.5, the ileal P digestibility was reduced (P < 0.05) from 63% to 42%, respectively. The P bioavailability of conventional DDGS relative to KH2PO4 based on bone ash data was also determined. Bioavailability of P based on bone ash content (mg/tibia) was 61%. This value was similar to P digestibility when a 1.3 Ca:total P ratio was used. Results from these studies indicate that CFP, HP-DDGS, and RFHP-DDGS have improved nutritional value for poultry compared with conventional DDGS. It was also observed that RP-DDGS contained both a lower total and digestible P content relative to conventional DDGS, and the P digestibility and bioavailability of conventional DDGS was frequently influenced by the method used (precision-fed chicks, ad libitum-fed chicks, relative bioavailability based on bone ash) and dietary Ca level.