Concentration–time of fatty acids in the plasma of enterotoxigenic Escherichia coli (ETEC) K88–challenged pigs with or without KR-32. Nine fatty acids C14:0 (A), C16:0 (B), C16:1 (C), C18:0 (D), C18:1 (E), C18:2 (F), C20:3 (G), C20:4 (H), and C22:6 (I) were detected. The sum of these 9 fatty acids was shown as total fatty acids (J). *P <0.05 for the K88 group vs. the K88 + APK group; APK = antimicrobial peptide KR-32. CON-2 = piglets with an oral administration of fresh Luria–Bertani broth (50 mL) followed by an intraperitoneal (i.p.) injection of an equivalent volume of PBS; K88 = piglets orally challenged with 1 × 1010 cfu ETEC K88 on day 1 followed by an i.p. injection of an equivalent volume (1 mL) of PBS; K88 + APK = piglets orally challenged with 1 × 1010 cfu ETEC K88 on day 1 followed by an i.p. injection of 0.6 mg/kg KR-32 in Exp. 2. Results are means and SEM (n = 6 for the CON-2 group, n = 5 for the K88 group, and n = 5 for the K88 + APK group).