Effect of olive leaf (Olea europaea L.) extract addition to broiler diets on the growth performance, breast meat quality, antioxidant capacity and caecal bacterial populations

Abstract

This study aims to evaluate the effect of olive leaf extract (OLE) on growth performance, breast meat quality, antioxidant capacity and caecal microbiota regulation. OLE containing 51.5% oleuropein, 25.6% polyphenols and 6.2% flavonoids, was designed to different supplement levels ranging from 0.1% OLE (OLE0.1) to 0.5% OLE (OLE0.5) into a basal diet, separately. The whole feeding period lasts for 35 days after 7-day hatching from the egg. 720 1-day-age healthy Arbour Acres male broilers were thus divided into five experimental groups and one control group, consist of 20 broilers per group for six parallel experiments in triplicate. The results showed that the levels of average daily feed intake (ADFI) and average daily weight gain (ADG) of the broilers were decreased (p < 0.05) after the addition of 0.3% OLE. Moreover, the breast meat shear force was decreased by 34.4% (p < 0.05). The glutathione (GSH) levels in the meat were increased by 76.64% (p < 0.05); the levels of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) were increased by 50.4% and 120%, respectively. And the malondialdehyde (MDA) levels in the meat were reduced by 34.2% (p < 0.05). Additionally, a decreased intensity of Escherichia coli (p < 0.05) and an increased intensity of Lactobacillus and Bifidobacterium (p < 0.05) were observed. Overall, supplementing 0.3% OLE into daily diet enables enhancing breast meat antioxidation, amplifying the abundance of Lactobacillus and Bifidobacterium as well as diminishing the abundance of E. coli in the caecum. HIGHLIGHTS OLE contains 51.5% oleuropein, 25.6% of TP and 6.2% TF levels. OLE addition at 0.3% lowers shear force and raises the GSH’s level of the meat. OLE causes a decrease in E. coli and an increase in Lactobacillus and Bifidobacterium.