Passive immunity in the lamb. Effects of a second feed of colostrum on antibody absorption from the first feed.

Lambs were taken from their mothers before sucking and fed pooled colostrum (30 g/kg body weight), containing added antibody to egg albumin, 1 h after birth. At 4 h after feeding there was a two-fold range in immunoglobulin (IgG) concentration and a sixteen-fold range in anti-egg albumin activity in their sera. The coefficient of correlation between the IgG and antibody concentrations was significant but low (r = 0.445, P less than 0.02). When a second feed of colostrum without added antibody was given 6 h after the first, both the IgG and the antibody concentrations increased significantly, indicating that there had been increased absorption from the first feed, rather than absorption from the second. The increases in IgG had a significant negative correlation with the IgG concentrations before the second feed (r = 0.760, P less than 0.001). Sera from control lambs fed only untreated colostrum gave only trace, probably non-specific, antibody reactions. The results suggest that single feeds of colostrum are generally inefficient, and that the passive immune status of young lambs may be improved and made more uniform by subsequent feeds, even though these may be themselves deficient in IgG.