effects of drinking thyme essence (thymus vulgaris l.) on growth performance, immune response and intestinal selected bacterial population in broiler chickens

this study evaluated the effects of drinking thyme essence (dte) (zero, 0.10, 0.15 and 0.20 ml/l) on growth performance, immune response and changing of intestinal bacterial population in broiler chickens. a total number of 500 day old male broiler chicks (ross 308), were randomly assigned to 4 treatments with 5 replicates and 25 chickens per each, based on a completely randomized design (crd). growth performances were assessed during the range of 8-21, 22-42 and 8-42 d. at 21 and 42 d blood serum titers including: newcastle disease (nd), avian influenza (ai), infectious bronchitis virus (ibv) and infectious bursal disease (ibd) were sampled. bacterial populations in intestinal digesta were determined at the age of 21 and 42 d. dte levels significantly (p) improved total weight gain and total feed conversion ratio  as compared with the control group during 1-42 d of age. the titer of serum antibodies did not show significant differences between different treatments at the 21 or 42 d. total count, e. coli, and gram negative bacteria (gnb) at the age of 21 and 42 days showed a significantly (p) lower number compared with the control group. there was a significantly (p) higher number of lactic acid bacteria (lab) in dte groups compared with control group at both ages of 21 and 42 d. in conclusion, different levels of dte (especially at level of 0.20 ml/l) could improve the growth performance, immune response and intestinal lactic acid bacteria as a health index during different growth periods.