Effects of seaweed on blood plasma immunoglobulin concentration, mucosal immunity, small intestine histomorphology, cecal microbial population, and volatile fatty acid profile in broiler chickens

Abstract

Background and aim: Seaweeds, particularly brown seaweed (BS) and green seaweed (GS), are rich in bioactive compounds that may enhance poultry health and productivity. This study evaluates the effects of dietary BS and GS on blood plasma immunoglobulin concentrations, mucosal immunity, small intestine histomorphology, cecal microbial populations, and volatile fatty acid (VFA) profiles in broiler chickens.

Materials and methods: A total of 504 one-day-old male broilers were randomly assigned to 12 dietary treatments: A negative control (basal diet), a positive control (basal diet + 100 mg/kg Vitamin E), and diets supplemented with BS and GS at 0.25%, 0.50%, 0.75%, 1.00%, and 1.25%. The study followed a completely randomized design, with data analyzed using a one-way analysis of variance and Duncan's multiple range test (p < 0.05).

Results: Broilers fed 0.75%, 1.00%, and 1.25% GS exhibited significantly higher (p < 0.05) blood plasma immunoglobulin A (IgA) and immunoglobulin G (IgG) concentrations. Dietary BS and GS inclusion upregulated messenger RNA expression of interleukin-6, interleukin-10, and interferon-gamma, indicating immunomodulatory effects. Jejunal villus height was significantly increased in birds fed 0.50%, 0.75%, and 1.25% BS during the starter period. Birds receiving 0.50% BS, 0.25% GS, and 0.50% GS exhibited higher cecal Lactobacillus counts, whereas 0.75% BS and GS significantly reduced Escherichia coli populations. Furthermore, higher total VFA and propionic acid concentrations were observed in birds supplemented with 1.00% and 1.25% GS, as well as 1.25% BS.

Conclusion: The inclusion of GS (0.75%, 1.00%, and 1.25%) in broiler diets enhances immune response by increasing IgA and IgG levels. Both BS and GS positively modulate cytokine expression, intestinal morphology, and microbial balance, leading to improved gut health. The results suggest that BS and GS supplementation may serve as sustainable feed additives to enhance broiler performance while reducing reliance on synthetic supplements. Future studies should focus on identifying the bioactive compounds responsible for these effects and their broader implications for poultry production.

Keywords: broiler chickens; cytokine expression; gut health; immunoglobulin; seaweed supplementation; sustainable poultry nutrition; volatile fatty acids.