Dietary licorice (Glycyrrhiza glabra) supplementation enhances growth, antioxidant defence, and modulates metabolic enzyme activity in Labeo rohita

This study aims to assess the impact of liquorice (Glycyrrhiza glabra) on the growth, immunity, digestive enzyme activity and metabolism of Labeo rohita. Five isonitrogenous (30% crude protein) and isocaloric diets were formulated with licorice incorporated at 0%, 1%, 2%, 3%, and 4%, and were designated as C (control), T1, T2, T3, and T4, respectively. A total of 225 L. rohita fingerlings (5 ± 0.5 g) were randomly stocked in triplicate FRP tanks (15 fish per tank). After 60 days of experimental feeding, licorice inclusion significantly (p<0.05) enhanced growth performance and feed conversion efficiency in Labeo rohita fingerlings compared to the control group. Fish fed the T3 diet (3% licorice) exhibited significantly greater weight gain (%) and specific growth rate, coupled with a lower feed conversion ratio. Lipase activity was significantly affected (p<0.05), with the highest activity observed in the T3 group. Muscle aspartate transaminase (AST) and alanine transaminase (ALT) activities were significantly higher (p<0.05) in the T4 group compared to the control. The highest superoxide dismutase (SOD) activity was recorded in the T4 group, which was higher (p<0.05) than the control and other dietary treatments. Similarly, catalase activity increased with higher licorice inclusion, showing significant elevation (p<0.05) in the T3 and T4 groups relative to the control. Serum protein and globulin levels significantly(p<0.05) vary between controls and treatments. The highest NBT activity was observed in the T1-fed group; however, it did not differ significantly from the other treatment groups, although it was higher compared to the control group. The study revealed that licorice supplementation promotes growth and immunity in fish.