Effects of Different Levels of Licorice (Glycyrrhiza glabra) Medicinal Plant Powder on Performance, Egg Quality and some of Serum Biochemical Parameters in Laying Hens

An experiment was conducted to evaluate the effects of different levels of licorice powder (LP) in diet on performance, egg traits and some serum biochemical parameters of laying hens in the late laying period. Totally 180 Hy-Line W-36 layer hens aged 55-68 weeks with similar weight were selected and assigned to 5 treatments, 3 replicates and 12 hens in each replicate in a completely randomized design. Experimental groups included 1) basal diet (without LP), 2, 3, 4 and 5) basal diet supplemented with 0.5, 1.0, 1.5 and 2.0% of LP, respectively. The results showed that the use of different levels of LP significantly affected the performance and egg traits of laying hens (P<0.01). The highest performance for egg production (60.96%), egg weight (61.50 g), egg mass (37.60 g) and the best feed conversion ratio (2.93) was achieved with 2% LP treatment. The amount of daily feed intake was not affected by dietary treatments. The highest amounts of yolk weight (29.43%), egg shell thickness (0.366 mm), haugh unit (74.79) and yolk color index (4.78) were obtained using 2% LP diet. Licorice powder supplementation in the diets of hens did not significantly alter the serum blood parameters compared to the control (P>0.05). It can be concluded that in laying hens in late laying period, using 2.0% of Licorice powder, without having any significant effects on serum bio-chemical parameters, can improve their performance and egg traits.