Evaluating The Effects Of Prophylactic Antibiotics On Intestinal Health In Pigs Given A Corticotropin-Releasing Factor Antagonist During Weaning And Transport

Abstract Prophylactic antibiotics improve intestinal health in pigs; however, it is unknown whether their efficacy interacts with a pig’s stress response following weaning and transport. The study objective was to determine whether a corticotropin-releasing factor (CRF) antagonist would impact the efficacy of prophylactic antibiotics on improving intestinal health in transported weaned pigs. Mixed-sex pigs (n = 56; 5.70 ± 1.05 kg BW) were weaned (20.49 ± 0.64 d), a blood sample was taken, pigs were given an i.p. injection of saline (SAL) or a CRF antagonist (CRFA; 30 µg/kg BW; Astressin B), and then were transported for 12 h. Pigs were given a second and third i.p. injection at 6 and 12 h of transport, respectively. Following transport, 4 SAL and 4 CRFA pigs were blood sampled and euthanized. The remaining 48 pigs were individually housed and assigned to an antibiotic [A; chlortetracycline (441 ppm) + tiamulin (38.6 ppm)] or no antibiotic (NA) diet treatment balanced by injection treatment (n = 12 pigs/treatment combination). Blood was collected at 12 h and on d 3, 7, and 14 and pigs were euthanized on d 7 (n = 24) and d 14 (n = 24) post-weaning and transport. Plasma adrenocorticotropic hormone was reduced overall (P = 0.05; 9.1%) in CRFA versus SAL pigs. On d 7, jejunal villus height was greater (P = 0.04; 33%) in A versus NA pigs. Jejunal zonula occludens-1 (58.8%) and ileal claudin-1 (100.5%) mRNA abundance tended to be increased (P = 0.09) in CRFA+NA versus SAL+NA pigs on d 7. On d 14, jejunal tumor necrosis factor-alpha mRNA abundance was reduced (P = 0.02; 29.9%) in A versus NA pigs and jejunal glucagon-like peptide-2 mRNA abundance was increased (P = 0.03) in CRFA+NA versus SAL+NA (48.4%) and SAL+A versus SAL+NA (55.8%) pigs. No intestinal health parameter differences were detected (P > 0.05) between CRFA+NA and SAL+A pigs. In conclusion, CRFA and A impacted weaned pig intestinal health measures at similar levels.