THE MECHANISM, ISOTYPES INVOLVED AND EFFECT OF PASSIVE IMMUNOGLOBULIN TRANSFER TO THE NEWBORN ALPAC

Total serum protein of 10 newborn alpaca (Lama pacos) increased linearly (r = 0.98) from a presuckle mean of 4.7 g/dl ((+OR-)0.5 SD) to a maximum at 24 hours of 8.0 g/dl ((+OR-)1.4 SD). Electrophoretically, the increase consisted predominantly of gammaglobulins which contained IgG identified by reaction with antisera to sheep and goat IgG. In immunodiffusion, alpaca IgG was partially identical with human IgG and alpaca IgM partially identical with bovine IgM.;Alpaca IgG had a molecular weight 168 Kd, gamma mobility and an extinction coefficient (E(,280)('1%)) of 14.1. Serum IgG increased linearly (r = 0.97) from a presuckle mean of 0.3 mg/ml ((+OR-)0.1 SD) to a maximum of 30.1 mg/ml ((+OR-)8.1 SD) at 24 hours. Alpaca IgM had a molecular weight 990 Kd, beta mobility and E(,280)('1%) 12.8. Serum IgM increased linearly (r = 0.99) from a presuckle mean of 0.5 ((+OR-)0.1 SD) to a maximum of 4.2 mg/ml ((+OR-)2.2 SD) at 24 hours. IgG and IgM decreased to one half in 10 and 7 days respectively. IgG and IgM antibodies to chicken RBC had 24 hour geometric mean titers of 1139 and 843, respectively, decreasing to one half in 6 and 3.8 days.;Failure of passive immunoglobulin transfer (FPT) from colostrum was the major determinant of cria mortality. Crias dying with infections had 48-hour serum IgG lower (p < 0.0001) than live crias. Ten of 82 crias examined died, seven of these had 0-9 mg/ml serum IgG after birth and all 7 had evidence of infection, 2 had 10-19 mg/ml serum IgG and one had 20 mg/ml. FPT was defined as a 48 hour serum IgG 2 SD below the normal mean; 9% of crias had FPT.;Postmortem serum IgG of 5 crias that died at 2-10 days of age ranged from 2 SD below the normal mean. Serum IgG was 2 to 21 mg/ml in 8 crias that died at 11-20 days of age; 1 was >2 SD and 6 were >1 SD below the mean. Eight crias that died at 21-30 days of age had serum IgG 7-37 mg/ml; 3 were >1 SD below the mean. Lesions compatible with infections were present in 19 of 21 dead crias (90%).;Thirty six percent of the dams with <70 mg/ml colostrum IgG had crias with FPT that died while only 12% of the dams with 71-130 mg/ml had crias with FPT that died.