Comparative effects of probiotic and postbiotic in ovo administration on broiler intestinal development and health

The increasing global demand for animal protein necessitates sustainable poultry production strategies prioritizing poultry flocks' health and welfare. This study investigates the effects of in-ovo administration of probiotic consortia and their corresponding postbiotics on the intestinal health of broiler chickens. Probiotic strains, first isolated from the cecal contents of the healthy, untreated broiler chickens and survived under gastrointestinal tract conditions, were amplified by the 16S rDNA gene sequencing method and using the database of NCBI GenBank (National Center for Biotechnology Information), multiple alignments were done with some selected and related sequences using MEGA 12 software. Selected strains for animal experiments were combined to form a consortium and their corresponding postbiotics. A total of 480 fertilized Ross 308 broiler eggs (n = 120 per group) were divided into four groups: a negative control, a positive control injected with phosphate-buffered saline, a postbiotic group injected with 0.5 mL of cell-free supernatant from a probiotic consortium, and a probiotic group injected with 0.5 mL of the probiotic consortium itself (10⁸ CFU/mL). All injections were administered in ovo on day 17 of incubation, and samples were collected on day 21 of incubation and day 1 post-hatch for analysis. Histological and immunohistochemical analyses were performed on intestinal tissues to assess goblet cell activity, cellular proliferation, and the expression of heat shock proteins (HSP27, HSP60, HSP70, HSP90). Results indicated that both probiotics and postbiotics significantly enhanced goblet cell numbers (p ≤ 0.05) and PCNA expression (p ≤ 0.01), particularly in the duodenum. The postbiotic group demonstrated increased expression of heat shock proteins (p ≤ 0.05) and higher PCNA levels (p ≤ 0.01) compared to the probiotic group in the duodenum, indicating a stronger cellular stress response and proliferative activity. These findings highlight the potential of postbiotics as functional biological agents to enhance early gut development and stress adaptation, offering promising applications in poultry production systems aimed at improving intestinal health and reducing reliance on conventional inputs.