The effect of a non-antibiotic growth promoting component composed of natural phytomolecules, direct fed microbials, glucomannan oligosaccharides and organic acids on the performance, intestinal morphology and microbiology, plasma biochemistry, enzyme activities, visceral organ weights and immune response of commercial broilers challenged with Escherichia coli was investigated. Three hundred and sixty at one-day old male Ross 308 broiler chicks were randomly divided to the basal diet (control, CON); control plus 0.5 ml of culture materials containing 108 CFU/ml of E. coli (E. coli); control with 400 mg/kg bacitracin methylene disalicylate (an antibiotic growth promoter, AGP); control plus 1000 g/ton of feed of a blended mixture of natural feed additives (NAT); the combination of E. coli and AGP treatments (E. coli + AGP); or the combination of E. coli and NAT treatments (E. coli + NAT). E. coli injection decreased broiler performance by lowering body weight and increasing feed consumption, whereas AGP and NAT treatments improved body weight and the feed efficiency when compared to the other groups. However, feed intake was not affected by treatment. Immune response also improved on addition of NAT, compared with control. Blood biochemistry parameters were significantly affected by the treatments. Nutrient digestibilities were increased by AGP and NAT supplementation in E. coli challenged groups. Both AGP and NAT significantly decreased E. coli and coliform numbers in ceca. Ileal villus height was not affected by treatment, but ileal crypt depth and goblet cell counts decreased in the NAT relative to control group. AGP was somewhat more effective overall in improving broiler growth and health characteristics than NAT, but since NAT generally improved broiler performance compared to the control group, it can be alternatively used as an alternative to AGPs in commercial broiler production.
