Evaluation of acquired passive immunity in mule foals up to 60 days of age.

Ten mule foals were used to investigate serum IgG concentration. Blood was collected from mares and foals on the day following parturition (D1), at 48 and 72 hr after birth (D2 and D3), and on D7, D14, D21, D28, D35, D42, and D60. Serum IgG concentration was determined by zinc sulfate turbidity test and was above 400 mg/dl at all time points, except for one foal on D2.