91 Effects of antibiotics on growth performance, diarrhea, and bacterial translocation in weanling pigs experimentally infected with a pathogenic E. coli

Abstract

Abstract The experiment was conducted to investigate the effects of antibiotics on growth performance, diarrhea, fecal β-hemolytic coliforms, and bacterial translocation of weaned pigs experimentally infected with F18 Escherichia coli (E. coli). Twenty-six pigs (6.88 ± 1.03 kg BW) were individually housed in disease containment rooms and randomly allotted to one of three treatments with 8–9 replicate pigs per treatment. The three dietary treatments were control diet and 2 additional diets supplemented with 0.5 or 50 mg/kg carbadox, respectively. The experiment lasted 18 d (7 d before and 11 d after first inoculation [d 0]). F18 E. coli inoculum was daily and orally as 1010 cfu/3 mL for 3 days. Growth performance was measured on d -7 to 0 before inoculation, and d 0 to 5 and 5 to 11 post-inoculation (PI). Diarrhea scores were daily checked throughout the experiment. Fecal samples were collected on d 2, 5, 8, and 11 PI to test the percentage of β-hemolytic coliforms in total coliforms. Bacterial translocation was measured in lymph nodes on d 5 and 11 PI. All data were analyzed by ANOVA using PROC MIXED of SAS. Pigs supplemented with high-dose of antibiotics had greater (P < 0.05) final BW and lower (P < 0.05) overall frequency of diarrhea, compared with pigs in control and low-dose antibiotics groups. Pigs supplemented with low-dose antibiotics had lowest (P < 0.05) ADG and feed efficiency from d 0 to 5 PI, and had highest (P < 0.05) percentage of β-hemolytic coliforms in fecal samples on d 2 and 5 PI, and greatest (P < 0.05) bacterial colonies in mesenteric lymph nodes on d 11 PI, compared with pigs in the other two groups. In conclusion, low dose antibiotic supplementation exacerbates the detrimental effects of E. coli infection on pig performance and diarrhea.