Effect of Thyme essence on growth traits, mortality, pH and changing of intestinal bacterial population in broiler chickens

This study was conducted to evaluate the effect of thyme essence on the performance traits, mortality, pH and changing of intestinal bacterial population of broiler chicks. A total number of 500 one day old Ross-308 male broiler chickens were allocated randomly to 4 treatments. Replicates were 5 for each treatment with 25 chicks per each unit using a CRD statistical plan. Duration of experiment was 42 days and diets were similar with respect of Energy, Protein and other nutrients for all treatments. Treatments including plane water without thyme essence as control group and levels of 0.1, 0.15 and 0.2 percent of drinking thyme essence as experimental groups. Performance traits were included daily feed intake, gain and feed conversion ratio at the whole of experimental period. The gut pH at the ileum area was measured, also the selected intestinal bacterial population including Coli form, G- (gram negative bacteria) and Lactobacillus (lactic acid bacteria), counted and determined via gut samples at the age of 21 and 42 days. According to the results, the highest feed intake belonged to treatment of 0.2% (87.29 g/day) and lowest to control group (84.99 g/day) (p<0.05). The highest daily gain belonged to treatments 0.2 and 0.15% respectively (52 and 51.30 g/day), and lowest to control group (48.11 g/day) (p<0.05). The lowest feed conversion ratio belonged to treatment 0.15% (1.67) and then to treatments 0.2 and 0.1% respectively (1.70 and 1.71), and highest to control group (1.77) (p<0.05). The lowest mortality percentage belonged to treatment 0.1% (p<0.05). Gut pH of thyme essence treatments were significantly (p<0.05) lower than control group at both 21 and 42 days of age. The results of counting the intestinal bacterial populations at both ages showed that the lowest Coli forms and gram negative bacteria, in contrast, the highest Lactobacillus number were belonged to thyme essence treatments (p<0.05).