Effect of Supplementation of Licorice Root (Glycyrrhiza Glabra L.) Extracts on Immune Status in Commercial Broilers

Abstract

An experimental study was designed with the objective of exploring the effect of supplementation of Glycyrrhiza glabra extracts on immune status in commercial broilers. Fifty four, day old, straight run broiler chicks were randomly allotted to 3 treatment groups (T₁ - unsupplemented; T₂ - supplemented with 1% G. glabra crude extract powder and T₃ - supplemented with 0.1% G. glabra standardized extract powder) consisting of three replicates of six chicks each. The birds were reared under standard and uniform management conditions throughout the experimental period. Ranikhet-LaSota strain was used to produce antibodies against Ranikhet disease virus. All the birds were also immunized against Sheep Red Blood Cells (SRBC). HI titre values against Ranikhet (LaSota) and HA titre values against SRBC antigens were estimated to assess the humoral immunity. The Serum Biochemical Parameters viz., serum total protein and albumin were estimated and serum globulin and albumin:globulin ratio were calculated. To assess the cell mediated immunity, total and differential white blood cell counts were performed. The group supplemented with 0.1% licorice standardized extract has shown significantly (p<0.01) higher HI titre value against Ranikhet disease virus, than the other groups, on day 42, whereas, there was no significant differences among the groups on days 7, 14, 21, 28 and 35 in HI titre values. Licorice root standardized extract supplemented group performed better than other groups in increasing HI titre values throughout the study period. Against SRBC antigen, significant differences (p<0.01) were observed among the groups on days 21, 28, 35 and 42 in HA titre values (p<0.01). Licorice root standardized extract supplemented group performed better than other groups in increasing HA titre values throughout the study period. No significant differences were noticed among groups in 2 weeks and 6 weeks except on 4 weeks in which significant (p<0.01) differences were noticed in serum albumin, serum globulin and albumin:globulin ratio. No significant differences were observed in the total WBC and differential cell counts throughout the study period among different treatment groups. This shows that licorice root extracts do not have any direct effect on cell mediated immunity.