Effect of in ovo administration of inulin and Lactococcus lactis on immune-related gene expression in broiler chickens.

OBJECTIVE To evaluate the effect of in ovo administration of inulin and Lactococcus lactis on immune-related gene expression in broiler chickens. ANIMALS 45 Ross broilers. PROCEDURES On day 12 of embryonic development, 360 eggs were equally allocated among 3 treatment groups and injected with 0.2 mL of a solution that contained 1.76 mg of inulin (prebiotic group) or 1.76 mg of inulin enriched with 1,000 CFUs of L lactis subsp lactis 2955 (synbiotic group), or they were injected with 0.2 mL of saline (0.9% NaCl) solution (control). At 1, 14, and 35 days after hatching, 5 male birds from each group were euthanized, and the spleen and cecal tonsils were harvested for determination of interleukin (IL)-4, IL-6, IL-8, IL-12p40, IL-18, cluster of differentiation 80, interferon-β, and interferon-γ expression by means of a reverse transcription quantitative PCR assay. Gene expressions in the cecal tonsils and spleens of chickens in the prebiotic and synbiotic groups were compared with those of control chickens at each tissue collection time. RESULTS Compared with control birds, immune-related gene expression was downregulated in birds in the prebiotic and synbiotic groups, and the magnitude of that downregulation was more pronounced in the cecal tonsils than in the spleen and increased with age. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that in ovo administration of a prebiotic or synbiotic to broilers was associated with downregulation of immune-related gene expression in the cecal tonsils and spleen. The magnitude of that downregulation increased with age and was most likely caused by stabilization of the gastrointestinal microbiota.