Dietary supplementation of extracts of red sea weed (Kappaphycus alvarezii) improves growth, intestinal morphology, expression of intestinal genes and immune responses in broiler chickens.

Abstract

Effects of supplementation of dried alkaline (referred to as MVP1) and aqueous (referred to as PBD1) extracts of Kappaphycus alvarezii, were evaluated in broiler (Vencobb 400) chickens (1-35 days post-hatch). In experiment I, each of the seven diets (basal diet with three levels (0.5, 1.5 or 5.0 g kg-1 diet) of MVP1 or PBD1 and a negative control was fed to 12 pen replicates containing five birds in each. In experiment II, each of three diets [a negative control, and PBD1 at two levels (1.0 or 1.5 g kg-1 diet)] was fed to 16 pen replicates of five chicks in each. Concentrations of total phenolics, phycobillins and free radical scavenging activity were higher (P < 0.01) whereas carrageenan was lower in PBD1 than in MVP1. In the experiment I, PBD1 at 1.5 g kg-1 diet improved (P < 0.05) body weight (BW) (7.11% higher). In the experiment II, both the treatments improved (P < 0.01) BW (9.18% and 8.47%, respectively) compared to the control. The group fed with PBD1@ 1.0 g kg-1 had higher (P < 0.05) haemagglutination inhibition titre, expression of intestinal claudin 2, TLR2A, NOD1, avian beta defensin 4, interleukin 2 and interleukin 6 genes than control. Treatments did not influence feed efficiency or levels of most of the antioxidant enzymes. Villus width and crypt depth were significantly higher in the group fed with 1.5 g kg-1 of PBD1. Supplementing dried aqueous extract of K. alvarezii at 1 g kg-1 diet may be an effective strategy to increase growth and immunity in broiler chickens. © 2020 Society of Chemical Industry.