Eighty Holstein and Holstein cross dairy calves were blocked by birth date and randomly assigned to 1 of 8 treatments within each block to examine the effect of a colostrum replacer (CR) feeding regimen, supplementation of CR with sodium bicarbonate (NaHCO3), and provision of a milk replacer (MR) feeding on IgG absorption. Calves were offered a CR containing 184.5g/L of IgG in either 1 feeding at 0h (within 30 min of birth), with or without 30g of NaHCO3, with or without a feeding of MR at 6h of age, or 2 feedings of CR (123g of IgG at 0h with or without 20g of NaHCO3 and 61.5g of IgG at 6h with or without 10g of NaHCO3), with or without a MR feeding at 12h. Therefore, treatments were (1) 1 feeding of CR; (2) 2 feedings of CR; (3) 1 feeding of CR + 30g of NaHCO3; (4) 2 feedings of CR + 30g of NaHCO3; (5) 1 feeding of CR + MR feeding; (6) 2 feedings of CR + MR feeding; (7) 1 feeding of CR + 30g NaHCO3 + MR feeding; and (8) 2 feedings of CR + 30g NaHCO3 + MR feeding. Blood samples were obtained at 0, 6, 12, 18, and 24h after birth and were analyzed for IgG via radial immunoassay. Results indicated that CR feeding schedule, MR feeding, and the interactions CR × Na, CR × MR, and CR × Na × MR were similar for 24-h serum IgG, apparent efficiency of absorption, or area under the curve. Serum IgG at 24h, apparent efficiency of absorption, and area under the curve were decreased with addition of NaHCO3 compared with calves not supplemented with NaHCO3. These data indicate that supplementation of CR with NaHCO3 is not beneficial to IgG absorption and feeding MR within 6h of CR feeding does not affect IgG absorption.
