European Journal of Nutrition & Food Safety

This study evaluated the effects of dietary supplementation with a Lactobacillus DH42-based probiotic and its corresponding postbiotic on growth performance, carcass characteristics, blood biochemical indices, and gut health in Rainbow Rooster chickens. A total of 160 one-day-old mixed-sex chicks were randomly allocated to four dietary treatments, with five replicates of eight birds each (n = 8). The treatment groups included (1) a basal diet without growth promoters (CON), (2) a basal diet supplemented with enramycin (80 g/ton feed; AGP), (3) a basal diet supplemented with the Lactobacillus DH42 probiotic (PRO), and (4) a basal diet supplemented with the inactivated Lactobacillus DH42 postbiotic (POS). Growth performance was recorded weekly, while carcass characteristics, serum biochemical parameters, caecal microbiota, and intestinal morphology were evaluated on day 42. Average daily gain, carcass characteristics, and meat quality were not significantly affected by the dietary treatments (P > 0.05). However, birds receiving probiotic or postbiotic supplementation exhibited lower average daily feed intake during the finisher phase (22–42 d) and the overall experimental period (1–42 d), resulting in an improved feed conversion ratio compared with the CON and AGP groups (P < 0.05). Serum cholesterol concentration was significantly reduced in the PRO and POS groups relative to the CON group (P < 0.05). Probiotic supplementation significantly reduced caecal Salmonella counts compared with the CON and AGP groups (P < 0.05), whereas Escherichia coli and Lactobacillus populations remained unaffected. Postbiotic supplementation increased villus height in the jejunum and ileum, while both probiotic and postbiotic supplementation increased the villus height-to-crypt depth ratio in the duodenum (P < 0.05). These findings indicate that Lactobacillus DH42-derived probiotic and postbiotic supplementation improved feed efficiency and intestinal health without compromising growth performance, highlighting their potential as sustainable alternatives to antibiotic growth promoters in Rainbow Rooster chickens.