Modeling of growth performance, physiological response, and intestinal microbiota shift in growing Japanese quail fed olive leaf powder.

INTRODUCTION

Due to the anti-inflammatory, antioxidant, and antibacterial properties of olive leaf powder (OLP), it may serve as a beneficial feed supplement for birds. This study aimed to evaluate the effect of adding OLP to feed on growth efficiency, carcass traits, blood parameters, antioxidant activity, and cecal microbial load in growing Japanese quail.

METHODS

Three hundred and seventy-five one-day-old quail chicks were randomly assigned to five experimental groups, each containing five replicates of 15 birds: a control group fed a basal feed and four experimental groups given 3, 4, 5, and 6% OLP per kg of quail diets for the 6 weeks.

RESULTS

The results showed a significant (P < 0.05) improvement in growth performance, with increased live body weight (LBW) and an insignificantly improved feed conversion ratio in the 6% OLP group. Carcass yield and total edible meat also substantially improved (P < 0.05). Blood parameters showed improved (P < 0.05) protein and lipid levels and increased liver enzyme activity; moreover, the use of the OLP led to a decrease in TC, TG, LDL, and VLDL levels, as well as an increase in HDL. Additionally, the activity of antioxidant enzymes increased (P < 0.001), along with higher levels of GSH and SOD activity. All meat quality attributes, including cooking loss %, water-holding capacity, PH values, and meat color, improved (P < 0.05) with the use of OLP. Furthermore, intestinal microbiota analysis showed a significant improvement in Lactobacillus count and a decrease in pathogenic bacteria (total bacterial count, coliforms, E. coli, and Salmonella). However, the Bacillus count was not significantly affected by OLP supplementation.

DISCUSSION: The findings of this study demonstrate that OLP is a promising natural feed additive for growing Japanese quail, enhancing growth performance and the gut microbiome, thereby establishing it as a safe and natural growth promoter.