Estimating plasma volume in neonatal Holstein calves fed one or two feedings of a lacteal-based colostrum replacer using Evans blue dye and hematocrit values at various time points

Cabral, R. G., Chapman, C. E., Kent, E. J. and Erickson, P. S. 2015. Estimating plasma volume in neonatal Holstein calves fed one or two feedings of a lacteal-based colostrum replacer using Evans blue dye and hematocrit values at various time points. Can. J. Anim. Sci. 95: 293–298. Twenty-eight Holstein calves were blocked by birth date and randomly assigned to one of two treatments to investigate the effect of colostrum replacer (CR) feeding regimen on plasma volume (PV). Treatments were: (1) one feeding of CR (C 1 ; 3 L of reconstituted CR 675 g of powder providing 184.5 g of IgG at birth) or (2) two feedings of CR (C 2 ; 2 L of reconstituted CR at birth and 1 L of reconstituted CR at 6 h). By 6 h of age, all calves had received 3 L of CR providing 184.5 g of IgG. Plasma volume was estimated at 6, 12, 18, and 24 h after birth using Evans blue dye. No treatment effects were noted at any time points (P>0.05). Mean PV for all calves regardless of treatment at 6, 12, 18, and 24 h were 78.6, 89.2, 83.9, and 90.7 mL kg −1 of body weight, respectively. Plasma volume was correlated with hematocrit (HCT), initial HCT, and treatment. Hematocrit was correlated with PV, initial HCT, and body weight. Hematocrit for 6, 12, 18 and 24 h after birth can be predicted with an initial precolostral HCT determination.