Background:In this study it was determined that a Calendula officinalis water extract can reduce the immune response to three different viruses in broiler chickens, associated with improvement in body weights.Material/Methods: The experiment was conducted on broiler chickens divided into two groups of 105 birds each. The first group received a Calendula officinalis water extract orally, while the second group received drinking water only. All birds in the two groups were similarly exposed to three different live vaccine viruses. Quantitative assessment of humoral immunity to each of the 3 viruses and records of bursal and thymus weight indices were taken. Performance, as observed in weight records at 21 and 41 days of age, feed conversion, and% mortality up to market age, was also evaluated.Results: There was a reduction in immune response to IB virus at 42 days of age, to ND virus at 29 and 42 days of age, and to IBD virus at 14, 29, and 42 days of age in the Calendula officinals-treated birds in comparison with controls. This immune reduction in Calendula officinalis-treated birds was associated with insignificant reduction in the bursal weight index at 42 days of age and an improvement in mean weights at 21 and 41 days of age; the feed conversion and mortality rates were similar in the two groups (P>0.05).Conclusions: Calendula officinalis had an immunomodulation effect against three different live viruses in broiler chickens.

Keywords: Poultry Diseases - therapy, Body Weight - physiology, Bursa of Fabricius - immunology, Calendula, Chickens, Homeopathy, Immunity - drug effects, Phytotherapy, Plant Preparations - pharmacology, Poultry Diseases - therapy, Thymus Gland - immunology, Viral Vaccines - administration & dosage