Effects of dietary red seaweed (Gracilaria tenuistipitata) supplementation on growth performance, intestinal health, immune responses and meat quality in broiler chickens.

The present study evaluated the effects of graded dietary inclusion of Gracilaria tenuistipitata on growth performance, meat composition, intestinal morphology, gut microbiota, immune response and intestinal immune gene expression in broiler chickens. A total of 200 one-day-old commercial broiler chicks were randomly allotted to four dietary treatments containing 0% (control), 1%, 2% and 4% dietary red seaweed and reared for 35 days. Average daily gain (ADG) and average daily feed intake (ADFI) were significantly (P < 0.05) reduced during the starter and early grower phases at 4% inclusion, whereas birds receiving 1-2% red seaweed maintained growth performance comparable to the control. Feed conversion ratio was transiently impaired at 4% inclusion during early growth but did not differ among treatments over the entire experimental period. Overall ADG was significantly (P < 0.05) lower at 4% inclusion, while livability remained unaffected. Breast meat proximate and mineral composition were not altered by seaweed supplementation; however, selective enrichment of docosahexaenoic acid (DHA) was observed at 2% inclusion. Histomorphometric evaluation revealed improved villus development and mucosal adaptation, particularly at 1-2% inclusion. Caecal microbiota analysis demonstrated reduced Escherichia coli and increased Lactobacillus populations in seaweed-fed groups. Humoral immune response against Newcastle disease virus remained unaffected, whereas increased expression of TLR2A, IL6 and CLDN2 indicated modulation of intestinal immune and barrier-regulatory pathways. Overall, dietary inclusion of G. tenuistipitata at 1-2% appears to support favourable changes in gut health and intestinal immune-related responses while maintaining overall growth performance comparable to the control, whereas higher inclusion levels may impose nutritional limitations on growth.