Effects of intermittent and continuous organic acids in water on antimicrobial activity, intestinal morphology, gut microbiota, and growth performance of Campylobacter jejuni challenged or unchallenged broilers

This study evaluated the effects of organic acids (OA), Campylobacter jejuni (CJ) inoculation, and their combination on cecal CJ colonization, intestinal morphology, cecal microbiota, and broiler performance. A 4×2 factorial arrangement in a randomized complete block design was used, with pen location as the blocking factor. A total of 2,240 Ross 708 males were allocated into 64 pens (8 replicates/treatment; 35 birds/pen). Pens received one of four water treatments: control (water), intermittent OA-A (2 mL/L; days 0–5, then 1 day/week), continuous OA-A (2 mL/L), or continuous OA-B (2.6 mL/L), where OA-A and OA-B are citric acid-based water acidifiers. Birds were gavaged on day 21 with either phosphate buffered saline or CJ (10 4 CFU/mL). CJ enumeration was conducted on days 23, 28, 35, and 42. Duodenum, jejunum, and ileum samples were collected on day 42 for villus height, crypt depth, and villus-to-crypt ratio (V:C). Cecal contents were collected for microbiota analysis, and body weights and feed intake were recorded on days 0, 13, 27, and 41. Data were analyzed using ANOVA (GLIMMIX, SAS v9.4) and cecal microbiota data in R. OA supplementation did not reduce cecal CJ colonization (P>0.05). No interaction effects were found for intestinal morphology, but CJ-inoculated birds had deeper jejunal crypts (P=0.0018) and reduced ileal villus height and V:C (P=0.0134 and 0.0003). CJ altered microbiota alpha- and beta-diversity, but no interaction effects were observed. Broilers receiving citric acid-based OA-A had higher body weights than control and OA-B birds on day 41 (P=0.0029). In conclusion, OA did not reduce CJ colonization or improve gut morphology but improved final body weight.