Effect of withholding macromolecules on the duration of intestinal permeability to colostral IgG in foals.

OBJECTIVE To quantify absorption of colostral IgG by healthy neonatal foals and to test the hypothesis that delayed ingestion of macromolecules prolongs the duration of intestinal permeability to immunoglobulins (Ig) in newborn foals. ANIMALS Thirteen mixed breed foals. PROCEDURE Foals were randomly assigned to two treatment groups, which were fed either a glucose-electrolyte solution or a commercial milk replacer for 12 h after birth, before being fed a known amount of colostral IgG. A control group was fed a known amount of colostral IgG from birth. The efficiency of IgG absorption was calculated following determination of plasma IgG concentration for each foal. RESULTS Foals given colostrum immediately after birth transferred approximately 51% of ingested IgG into their vascular space. Delayed colostral ingestion significantly reduced the amount of IgG absorbed by foals. Withholding macromolecules for 12 h had no effect on the subsequent efficiency of IgG absorption. CONCLUSIONS Colostrum should be supplied to foals within 12 h of birth for best uptake of Ig. The type of fluid administered to foals before the ingestion of colostrum does not influence subsequent absorption of Ig, suggesting that the process of gut closure in foals is not mediated by a finite capacity for macromolecular uptake.