Effect of Feeding an Essential Oil Blend on Growth Performance, Nutrient Utilization, Intestinal Health and Humoral Immunity in Broiler Chicken

A study of 39 days duration was conducted on broiler chicken to ascertain the effect of an essential oil blend (EO), consisting of cinnamon oil, clove oil, and ajwain oil at equal ratio, on growth performance, nutrient utilization, intestinal microbial composition, intestinal morphology and humoral immunity. A flock of 288, day-old mixed sex broiler chicks were allocated to four dietary treatments (each treatment consisted of 8 replicate pens with 9 chicks in each pen): basal diet (control; CON), CON + 500 mg/kg of bacitracin methylene disalicylate (AGP), CON + 250 mg/kg of the EO (EO250), and CON + 500 mg/kg of the EO (EO500). Supplementation of AGP improved (P<0.05) average daily gain (ADG) and FCR during 1-14 d and 15-28 d, but not the overall (1-39 d) growth performance. Supplementation of EO had no effect on the above parameters. The apparent total tract digestibility (ATTD) of DM, OM and CP was not affected by any of the treatments. The count of E. coli and Clostridium spp in the caecum was lesser (P<0.05) in the group receiving AGP, compared with control, EO250 and EO500 groups, while that of Lactobacillus spp. was not affected by dietary treatments. Supplementation of EO did not influence intestinal morphology, but AGP significantly increased (P<0.05) villi height in the duodenum, jejunum and ileum in comparison to the control, EO250 and EO500 groups. Antibody titres against Newcastle disease virus (NDV) increased (P<0.05) following vaccination in the EO500 group compared to that in the control, EO250 and AGP supplemented groups. Serum catalase activity was higher (P<0.01) in EO500 group compared to other groups,while serum SOD activity was unaffected by treatments. In addition, the concentrations of serum glucose, total protein, triglyceride and cholesterol were not influenced by dietary treatments. It could therefore be concluded that supplementation with 500 mg/kg EO blend had a positive effect on immune response and antioxidant status of broiler chicken, with no effect on growth performance.