Failure in passive transfer of immunoglobulin G1 to lambs: measurement of immunoglobulin G1 in ewe colostrums.

Concentrations of immunoglobulin (Ig) G1 were measured in 590 sera from 24- to 36-hour-old lambs, and failure in passive transfer (FPT), less than 6 mg/ml, occurred in 20 lambs. Of the 20 FPT lambs, 45% died before 3 weeks of age, whereas only 5% of the 570 lambs with adequate passive transfer died before 3 weeks of age. The low percentage of FPT was attributed to management practices ensuring suckling by the lambs and possibly to influences from several years of selecting ewes on the basis of weaned lamb production. The correlation between the concentration of IgG1 in 257 postpartum, presuckle ewe colostrum samples and the IgG1 concentrations in 362 lamb sera from those ewes was low (r = 0.32). However, the mean serum IgG1 concentration in 20 lambs from ewes with the lowest postpartum, presuckle colostrum IgG1 concentrations (less than 30 mg/ml) was significantly lower (P less than 0.001) than mean serum IgG1 concentration in 24 lambs from ewes with the highest postpartum, presuckle colostrum IgG1 concentrations (greater than 110 mg/ml). Postpartum, presuckle colostrum IgG1 was measured in 7 ewes whose lambs had FPT, and the IgG1 values varied throughout the colostrum IgG1 range. Colostrum IgG1 concentrations could not be used to explain FPT or to identify ewes likely to have lambs with FPT.