Newborn pups from 4 large litters were alloted to 6 groups to determine effect of time and route of administration on absorption of an alternate source of immunoglobulin. Selective absorption of specific classes of immunoglobulins was also investigated. The alternate source of immunoglobulin consisted of pooled serum that was administered either PO or SC. Control groups were either left with the dam (group C1) or fed milk replacer (group C2). Blood samples were collected from pups at birth and 24 hours. Immunoglobulin (IgA, IgG, IgM) concentrations were determined by use of radial immunodiffusion on samples of pooled serum, colostrum, and pups' serum (birth and 24 hours). Serum IgA concentration was less than the sensitivity of the procedure and was not included in the statistical analysis. Pups fed 8 ml of pooled serum at birth and 12 hours later (group T1) absorbed more (P less than 0.05) IgG and IgM than did group-C2 pups, but less (P less than 0.05) than did group-C1 pups. Pups fed 8 ml of pooled serum at 12 hours only had significant (P less than 0.05) increase of IgG concentration, but no absorption of IgM (P greater than 0.05) at 24 hours, compared with control pups (group C2). Pups administered 8 ml of pooled serum SC at birth (group SC1) had similar (P greater than 0.05) absorption of IgG and higher (P less than 0.05) absorption of IgM than did pups of group T1.(ABSTRACT TRUNCATED AT 250 WORDS)