Use of liquorice (Glycyrrhiza glabra) in poultry nutrition: Global impacts on performance, carcass and meat quality

Supplementation of poultry diets with medicinal plants containing bioactive molecules have shown promising results in promoting growth performance, enhancing feed efficiency, and improving carcass traits and meat quality. There are many studies using herbal plants and their derivatives involving liquorice (Glycyrrhiza glabra), while studies using only liquorice are very limited. Liquorice contains bioactive components such as glycyrrhizin and flavonoids, and has been linked to many pharmacological effects like immunomodulatory, anti-oxidant, antiviral and anti-inflammatory activity. Supplementation of liquorice in poultry diets had beneficial impacts on growth and performance by improving organ development. In addition, there are appetite and digestion stimulating factors in liquorice. Dietary liquorice supplementation at level of 2.5 g/kg showed the best results in broiler chicken, and demonstrated it can be safely used in poultry diets. Addition of liquorice in diets up to 0.5% inclusion before sexual maturity enhanced performance of laying hens. Furthermore, broilers receiving drinking water containing 450 mg/l liquorice under heat stress significantly improved feed conversion and economic efficiency. Abdominal fat in broiler chickens was decreased when liquorice was included at 2 g/kg in feed or 0.3 g/l in drinking water. Broiler chickens with access to drinking water containing 450 mg/l of liquorice increased the dressing percentage, with or without giblets. Carcass organoleptics were improved in birds receiving drinking water with liquorice at levels of either 1, 2 and 4 mg/kg body weight. This review describes the chemical composition, health benefits and beneficial applications of the liquorice herb and its effect on growth and productive performance, carcasses and meat quality, which will be useful for researchers, physiologists, nutritionists, veterinarians, scientists, pharmacists, pharmaceutical industries, and poultry breeders.