Serum samples were collected between 24 and 48 h of age
from 408 Hereford calves of a selection experiment and from 200
Angus, Hereford and Red Poll calves of another experimental
population (Germ Plasm Utilization project). Concentrations of
Immunoglobulin G₁ (IgG₁) were determined by single radial
immunodiffusion. Breed or selection...