Fig. 3. Schematic illustration of experimental outline, timeline, and sampling.

A The study included 30, 23–26-day-old piglets from three sows divided into three groups (n = 10): piglets receiving either nonspecific V_HH Control; an ETEC LT⁺-targeting bivalent V_HH construct (BL2.2); or an ETEC F4⁺ fimbriae and LT⁺ targeting bivalent V_HH construct (BL1.2 + BL2.2) for two weeks. On days 1 and 2 after weaning, all pigs were orally challenged with an ETEC F4⁺LT⁺ strain. B Throughout the study, the piglets’ health condition, body weight, and feed intake were recorded; faecal samples were collected at specific timepoints.