Drinking water supplementation of licorice (Glycyrrhiza glabra L. root) extract as an alternative to in-feed antibiotic growth promoter in broiler chickens

The present study was conducted to determine the efficacy of licorice extract (LE) supplementation through drinking water as an alternative to an in-feed antibiotic growth promoter. A total of 400, 1-day-old broiler chickens (Cobb 500) were randomly divided into 20 separate floor pens each comprising 20 chickens and 4 pens (replicates) per treatment in a completely randomized design. The treatments included a control (no input), a diet containing 5 mg/kg antibiotic (lincomycin), and drinking water supplemented with 0.1, 0.2, or 0.3 g/L of LE, respectively. The body weight, feed intake, and feed conversion ratio were not significantly different among treatment groups (P > 0.05). Birds given drink water supplemented with 0.3 g/L of LE had significantly decreased abdominal fat percentage relative to control group (P < 0.05). Moreover, comparing with control, serum concentrations of glucose, low-density lipoprotein cholesterol and total cholesterol were decreased by LE supplementation at all three tested levels (P < 0.05). Dietary supplemental of antibiotics also caused significant decreases in total cholesterol and low-density lipoprotein cholesterol concentrations (P < 0.05). These results clearly showed that LE supplementation via drinking water had beneficial and positive influences on carcass quality and blood biochemical parameters of broiler chickens. However, because no significant difference was observed on growth performance among the broilers given the control, antibiotic, or the LE levels, further research is still needed to confirm the present results and to test the efficacy of LE as an alternative to an in-feed antibiotic growth promoter