Levels of total haemolytic complement activity in paired dairy cow-newborn calf sera.

Total haemolytic complement (CH50) activities of sera obtained from newborn dairy calves and their corresponding dams were compared. The differences between the mean maternal and neonatal CH50 concentrations were significant (P≤0.001). The concentration of CH50 units/ml in sera from 16 calves was 52.0 ± 21.4, whereas, for the cows it was I95.8 ±24.0. The ratio of cow:calf serum CH50 values averaged 4.24 with a range from 1.77 to 8.00. A positive rank correlation of 0.479 (P≤0.05) was found between the CH50 titres in calves and their dams. Anticomplementary substances were not detected in calf sera. The possible relationships between deficient CH50 levels in newborn calves and their susceptibility to infectious agents is discussed. [ABSTRACT FROM AUTHOR]