Effects of Oregano (Origanum vulgare L.) and Rosemary (Rosmarinus officinalis L.) Aqueous Extracts On in vitro Rabbit Immune Responses

Natural antioxidants are receiving increasing attention in human and animal nutrition because of their association with food quality characteristics and immune responses [1,2]. Among a variety of plants bearing anti-oxidative constituents, the Labiatae family (mint plants) has been attracting the greatest interest [3], with particular attention to products from oregano (Origanum vulgare L.) and rosemary (Rosmarinus officinalis L.). Oregano exerts a well documented anti-oxidative activity [46], but it also possesses intense in vitro antimicrobial [7] and antifungal [8] properties. Such properties make it an appropriate candidate as a replacement for antibiotic growth promoters and also a promising food additive in order to prevent meat lipid oxidation [9]. Indeed, oregano has been found to improve meat storage stability after slaughter in rabbits [10]. The rosemary extract exerts anti-oxidative activity, but its constituents have also shown a variety of pharmacological activities for cancer chemoprevention and therapy in in vitro and in vivo models [11]. The claim often made of phytogenic feed additives as stimulant of immune function however faces with a poor specific experimental verification in monogastric animals (Lagomorpha). Therefore there is a lack of data regarding the possible effects of plants extracts on immunity of these species. This study was designed to evaluate: 1) the effect of dietary plant extract (oregano and/or rosemary) and 2) age effect, on some specific immune responses (lymphocytes proliferation test and IgM measurements in vitro) and on peripheral blood lymphocyte subsets development in rabbits