Colostrum replacer feeding regimen,addition of sodium bicarbonate,and milk replacer: The combined effects on absorptive efficiency of immunoglobulin G in neonatal calves

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 184.5 g/L of IgG in either 1 feeding at 0 h (within 30 min of birth), with or without 30 g of NaHCO₃, with or without a feeding of MR at 6 h of age, or 2 feedings of CR (123 g of IgG at 0 h with or without 20 g of NaHCO₃ and 61.5 g of IgG at 6 h with or without 10 g of NaHCO₃), with or without a MR feeding at 12 h. Therefore, treatments were (1) 1 feeding of CR; (2) 2 feedings of CR; (3) 1 feeding of CR + 30 g of NaHCO₃; (4) 2 feedings of CR + 30 g of NaHCO₃; (5) 1 feeding of CR + MR feeding; (6) 2 feedings of CR + MR feeding; (7) 1 feeding of CR + 30 g NaHCO₃ + MR feeding; and (8) 2 feedings of CR + 30 g NaHCO₃ + MR feeding. Blood samples were obtained at 0, 6, 12, 18, and 24 h 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 24 h, 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 6 h of CR feeding does not affect IgG absorption.