Addition of casein or whey protein to colostrum or a colostrum supplement product on absorption of IgG in neonatal calves

The effects of the addition of nonimmunoglobulin protein on absorption of i mmunoglobulin G (IgG) from colostrum or colostrum supplement products were determined in two experiments. In experiment 1, 48 Holstein calves were fed 4 L of pooled maternal colostrum or 4 L of reconstituted colostrum supplem ent with 0, 200, or 400 g of added whey protein concentrate or casein. In e xperiment 2, 38 Jersey calves were fed 2 L of pooled maternal colostrum wit h 100 or 200 g of whey protein concentrate or casein added immediately befo re feeding. Blood was collected at 24 h of age and plasma IgG concentration , total protein, hematocrit (experiment 1 only), and plasma urea N were det ermined. In experiment 1, blood samples were also collected at 4, 8, 12, 16 , and 20 h to evaluate absorption of IgG and protein and urea N concentrati ons. The addition of 400 g of casein to colostrum supplement in experiment 1 reduced plasma IgG from 5.66 g/L (0 g of casein addition) to 3.88 g/L, in creased plasma urea N at 24 h, and reduced the change in plasma total prote in from 0 to 24 h. Hourly plasma IgG concentrations increased with the cons umption of colostrum or supplements but increased more rapidly in calves fe d whey protein concentrate and more slowly in calves fed casein. The additi on of 200 g of casein or whey protein concentrate to colostrum supplements had no effect on plasma IgG concentration at 24 h of age. The addition of 1 00 or 200 g of casein or whey protein concentrate to maternal colostrum had no effect on plasma urea N, total protein, or plasma IgG in experiment 2. The addition of nonimmunoglobulin protein to colostrum supplements or mater nal colostrum did not affect IgG absorption from the intestine of newborn c alves unless the amount of total protein exceeded 500 g of protein.