Estimation of plasma volume in Holstein and Jersey calves

The concentration of immunoglobulin (Ig) G in the blood of neonatal calves shortly after birth is a widely used criterion to determine the degree of acquisition of passive immunity. Another method used to determine the biological mechanisms of IgG absorption is calculation of the apparent efficiency of IgG absorption. Estimation of the efficiency of IgG absorption requires the estimation of plasma volume in neonatal calves. Previous estimates of plasma volume in a few calves of varying breeds have been made; the estimates ranged from 7 to 14.5% of body weight (BW). Holstein (n = 97 from four farms) and Jersey (n = 49 from one farm) calves were fed fresh maternal colostrum or colostrum that had been previously frozen. Calves were fed 2 L of colostrum at 4.1 h (SE = 0.2; range = 0.3 to 11.0 h) and 12 h later. Plasma volume was measured by determining the concentration of Evans' blue dye in a jugular blood sample collected 10 min after injection of approximately 1.5 ml of 1.5% Evans' blue dye. Factors that affected plasma volume (milliliters) were BW, breed, and age at sampling; r2 of the regression was 0.60. Factors that affected plasma volume (percentage of BW) were BW, breed, and age at sampling; r2 of the regression was 0.08. Mean plasma volume for all calves was 3162 ml (SE = 79) and was 9.86% of birth BW (SE = 0.15%). Mean plasma volume was 2250 ml (9.71% of BW) and 3623 ml (9.94% of BW) for Jersey and Holstein calves, respectively. Body weight was the best predictor of plasma volume.