Short communication: Addition of varying amounts of sodium bicarbonate to colostrum replacer: Effects on immunoglobulin G absorption and serum bicarbonate in neonatal calves1

Fifty-two dairy calves were blocked by birth date and, within each block, randomly assigned to 1 of 4 treatments to investigate the effects of incremental levels of sodium bicarbonate (NaHCO3) on IgG metabolism. Treatments were (1) colostrum replacer (CR) + 0 g of NaHCO3 (control); (2) CR + 15 g of NaHCO3; (3) CR + 30 g of NaHCO3; or (4) CR + 45 g of NaHCO3. Calves were fed colostrum replacer (>200 g of IgG) in one feeding within 45 min of birth (0 h) and 2 L of milk replacer at 12, 24, 36, and 48 h. Only calves born in calving pens from multiparous cows with no dystocia were used in this study. Blood samples were taken at 0, 6, 12, 24, and 48 h postpartum, and serum was analyzed for IgG using radial immunoassay and bicarbonate using spectrophotometry. Feeding increasing levels of sodium bicarbonate had negative linear effects on IgG concentration, IgG apparent efficiency of absorption, and IgG area under the curve, primarily due to the effect of the highest dose of NaHCO3 (45 g). Sodium bicarbonate treatments had no effect on serum bicarbonate concentration. However, area under the curve of serum bicarbonate increased linearly with the amount of NaHCO3 fed.