The aim of this study was to evaluate the effects of dietary Piriformospora indica (PI) and clove essence (CE) and a combination of them (synbiotic) on performance and biochemical parameters after induction of stress using dexamethasone. The experiment was performed with 320 male, one-day-old chicks (Ross 308) using eight experimental groups and five replications. In each replication, eight chickens were fed a maize-soy-based diet. Experimental groups included group 1 (T1): control diet (based on maize and soybean without any feed additives); group 2 (T2): control diet with 0.2 cc dexamethasone injection; group 3 (T3): control diet with 11.6 cc CE; group 4 (T4): control diet with 10 mg PI; group 5 (T5): control diet with 11.6 cc of CE with 0.2 cc injection of dexamethasone; group 6 (T6): control diet with 10 mg PI and 0.2 cc of dexamethasone; group 7 (T7): control diet with synbiotic containing 10 mg of PI with 11.6 cc of CE; group 8 (T8): control diet with synbiotic containing 10 mg of PI and 11.6 cc of CE with 0.2 mg dexamethasone injection. PI and CE were poured into the drinking water during the rearing period. After 31, 33, 38, and 40 days, 2 mg/kg BW of dexamethasone was injected in the right breast muscle of experimental groups 2, 5, 6, and 8; after 35 and 42 days, samples were taken. The addition of CE, PI, and the synbiotic, caused an increase in body weight gain, feed intake, and reduced FCR compared to the control group in experimental groups 3, 4, and 7. The addition of 11.6 cc CE and 10 mg of PI caused an increase in body weight gain and feed intake and reduced FCR compared to the control group. Dexamethasone (0.2 mg) led to damage of the lymph organs, body weight loss, a reduction in humoral immunity, and side effects on performance parameters. Clove extract and the prebiotic reduced the adverse effects of dexamethasone.

ABSTRACT 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 one-day old male Ross 308 broiler chicks were randomly divided into 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/t of feed of a blended mixture of natural feed additives (NAT); 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 intake, 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 with the 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. Antibiotic growth promoter was somewhat more effective 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 AGP in commercial broiler production.