Effect of inclusion of Shirazi thyme (Zataria multiflora Boiss) aqueous extract in drinking water on performance and immune responses of broilers

This study was conducted to investigate the effect of0 (control), 0.5, 1, 1.5 and 2 ml/L of Shirazi thyme aqueous extract in drinking water on performance and immune response in broilers. Two hundred one- day- old broiler chicks (Ross 308) were allocated to five treatments with four replicates and 10 birds per cage in a completely randomized design. Daily feed intake, daily body weight gain and feed conversion ratio were measured. The birds were chalenged by sheep red blood cell (SRBC) on days 8 and 22 of age and serum antibody levels produced in response to SRBC were measured on days 21, 28, 35 and 42. Skin response to Phytohemagglutinin-P (PHA-P) injection was assessed intradermally on day 16. The Shirazi thyme aqueous extract had no effect on feed intake, daily weight gain, feed conversion ratio and carcass traits. The consumption of 2 ml/L Shirazi thyme aqueous extract in drinking water increased total Anti-SRBC and IgM titers on day 21; 1 and 1.5 ml/L increased IgM titer on day 28; 0.5, 1.5 and 2 ml/L increased total Anti-SRBC and IgG titers on day 35 and 1.5 and 2 ml/L increased IgG titer on day 42 (P<0.05). Cell immunity in response to PHA-P injection was not affected by treatment groups. It can be concluded that Zataria multifora Boiss have no effects on performance and cell immunity but improve humoral immunity in broilers.