Cinnamaldehyde enhances in vitro parameters of immunity and reduces in vivo infection against avian coccidiosis.

The effects of cinnamaldehyde (CINN) on in vitro parameters of immunity and in vivo protection against avian coccidiosis were evaluated. In vitro stimulation of chicken spleen lymphocytes with CINN (25-400 ng/ml) induced greater cell proliferation compared with the medium control (P < 0·001). CINN activated cultured macrophages to produce higher levels of NO at 1·2-5·0 μg/ml (P < 0·001), inhibited the growth of chicken tumour cells at 0·6-2·5 μg/ml (P < 0·001) and reduced the viability of Eimeria tenella parasites at 10 and 100 μg/ml (P < 0·05 and P < 0·001, respectively), compared with media controls. In chickens fed a diet supplemented with CINN at 14·4 mg/kg, the levels of IL-1β, IL-6, IL-15 and interferon-γ transcripts in intestinal lymphocytes were 2- to 47-fold higher (P < 0·001) compared with chickens given a non-supplemented diet. To determine the effect of CINN diets on avian coccidiosis, chickens were fed diets supplemented with CINN at 14·4 mg/kg (E. maxima or E. tenella) or 125 mg/kg (E. acervulina) from hatch for 24 d, and orally infected with 2·0 × 10(4) sporulated oocysts at age 14 d. CINN-fed chickens showed 16·5 and 41·6 % increased body-weight gains between 0-9 d post-infection (DPI) with E. acervulina or E. maxima, reduced E. acervulina oocyst shedding between 5-9 DPI and increased E. tenella-stimulated parasite antibody responses at 9 DPI compared with controls.