The Effects of Different Levels of Dried Aerial Parts Powder and Extract of Pennyroyal (Mentha pulegium) Medicinal Plant on Performance, Egg Quality, Blood

This experiment was conducted to evaluate the effects of different levels of dried aerial parts powder and extract of pennyroyal (Mentha pulegium) medicinal plant on performance, egg traits, blood biochemical and immunity parameters of laying hens. Two-hundred-fifty-two Hi-line (W36 strain) laying hens from 46 until 58 weeks of age were used in a completely randomized design in 7 treatments and 3 replicates (12 birds per replicate). The treatment groups consisted of a control group (1) with no dried aerial parts powder or extract of pennyroyal supplementation, and experimental groups 2, 3 and 4 contained 0.5%, 1% and 1.5% of pen-nyroyal powder respectively, whereas experimental groups 5, 6 and 7 contained 0.1%, 0.2% and 0.3% of pennyroyal extract, respectively. Using different levels and forms of pennyroyal significantly affected the performance, egg traits, blood biochemical and immunity parameters of laying hens (P < 0.05). By increas-ing the level of pennyroyal extract to 0.2% and 0.3% of rations, the performance of laying hens signifi-cantly decreased, whereas pennyroyal powder improved the performance of laying hens, consequently the best feed conversion ratio (2.46) was achieved by using 1.5% pennyroyal powder. The highest specific gravity (1.092) and Haugh unit (89.22) were resulted in groups 5 and 6, respectively. The lowest amount of blood triglyceride (270.4 mg/dL) and the highest amounts of albumin (3.05 mg/dL), total protein (5.40 mg/dL) and uric acid (5.39 mg/dL) were observed in group 7. The lowest percent of hetrophil (9.67%) and the highest percent of lymphocyte (90%) were observed in group 2 and the highest amount of white blood cells (266601/mm3) was resulted in group 5. The overall results showed that the use until 1.5% of dried aerial parts powder and 0.1% of pennyroyal (Mentha pulegium) extract compared with control group had positive effects on performance of laying hens. Using different levels of pennyroyal powder and extract could change the egg traits, blood biochemical parameters and immunity levels of laying hens.