J. Dairy Sci. 84:2059–2065 American Dairy Science Association, 2001. Formulation of Colostrum Supplements, Colostrum Replacers and Acquisition of Passive Immunity in Neonatal Calves1

Provision of an adequate mass of IgG from maternal colostrum is essential to health and survival of neonatal calves. Colostrum supplements (CS) have been devel-oped to provide supplemental immunoglobulin when maternal colostrum is of poor quality. However, colos-trum replacers (CR) that provide ≥100 g of IgG have not been formulated. Our objective was to determine the absorption of IgG in newborn calves fed CS derived from bovine serum or CR derived from bovine immuno-globulin concentrate. The CS were prepared by collect-ing, processing, and spray drying bovine serum and blending with other ingredients to provide 45 to 50 g of IgG per dose. The CR were prepared by further processing bovine serum to increase IgG concentration to>50 % IgG and blending with other ingredients to provide 100 to 122 g of IgG per dose. Holstein calves (n = 160) were fed 90 to 244 g of IgG from CS or CR in 1 or 2 feedings in two experiments. Blood was collected from each calf by jugular venipuncture at 0 and 24 h of age and plasma IgG was determined by turbidimetric immunoassay. Apparent efficiency of IgG absorption was calculated. Plasma IgG concentrations at 24 h of age were indicative of IgG intake and averaged 5.5 to 14.1 g/L in calves fed CS and CR. Mean apparent efficiency of IgG absorption in calves fed CS was 25 and 28 % in experiments 1 and 2, respectively. Mean apparent efficiency of IgG absorption in calves fed CR ranged from 19 to 32 % and were affected by method of processing and number of times fed. Treatment of plasma with polyethylene glycol reduced the efficiency of IgG absorption in experiment 1. The addition of ani-mal fat to CR had no effect on IgG absorption. A second feeding of CR increased plasma IgG, but efficiency of absorption was reduced. Mean body weights at 60 d o