Effects of processing methods for soybean meal used in milk replacers on intestinal xylose uptake and serum antibody to soybean antigen when fed to calves of various ages

Milk replacer containing either heated soybean meal (commercial soybean meal), extruded soybean meal, ethanol-extracted soybean meal, fermented soybean meal or skim milk powder replacer (SMPR) was fed for 20 d to preruminant calves from either 6, 18 or 30 d of age (age groups 1, 2 and 3, respectively). Effects of these diets on intestinal absorption efficiency (using the xylose absorption test), serum antibody titres to the soybean allergens, and concentrations of immunoglobulin isotypes (IgG1, IgG2, IgM and IgA) were determined. Peak plasma xylose concentrations were highest in calves receiving SMPR; these values were 45.8, 56.3 and 54.0 mg dL−1 for calves in the three age groups, respectively. Calves in age group 1, fed the extruded soybean meal replacer, had the lowest peak plasma xylose concentration (32.8 mg dL−1). Increases in peak plasma xylose concentration were not observed in calves in age groups 2 and 3 relative to those in age group 1 for the heated soybean meal replacer unlike those noted in ...