Accuracy of prediction equations for in vitro nutrient disappearance of bakery byproducts in pigs

The objective was to evaluate the accuracy of previous equations for estimating the in vitro disappearance of nutrients in eight bakery byproducts for pigs using neutral detergent fiber (NDF) as an independent variable. The in vitro ileal disappearance (IVID) of dry matter (DM) and crude protein (CP) and in vitro total tract disappearance (IVTTD) of DM and organic matter (OM) were determined for the bakery byproducts using a procedure developed for pigs. The accuracy of previous equations was assessed. Results indicated that NDF in the eight bakery byproduct sources ranged from 1.5% to 38.4%. The NDF was negatively correlated with in vitro nutrient disappearance (r < –0.90; P < 0.01). No linear or mean bias was observed in the previous equations for the IVID of DM or IVTTD of OM. However, a mean bias was observed in the previous equations for the IVID of CP (intercept = 18.45 and P < 0.001) and IVTTD of DM (intercept = 5.90 and P = 0.031). In conclusion, the IVID of DM and IVTTD of OM were predicted well using NDF. However, caution is required when applying the equations for IVID of CP and IVTTD of DM to bakery byproducts with low fiber concentrations.