This study aimed to investigate the effect of supplemental camphor on the performance and immune functions of Japanese quail by feeding graded levels (0 (control), 250, 500, 750, 1000, 5000 or 10 000 ppm) of camphor during a 42-day feeding trial. In all, 280 1-day-old quail chicks were randomly assigned into 28 cages of 10 chicks each with separate feeders. The results clearly demonstrated that camphor did not have a significant effect on BW, BW gain, total experimental average daily feed intake, feed conversion ratio, internal organ relative weights and biochemical parameters such as uric acid, albumin, total protein and triglyceride; however, plasma cholesterol concentration was significantly different in a linear manner, in which 500 ppm of camphor resulted in a lower level of cholesterol. Alternatively, greater concentrations of glucose and high-density lipoprotein (HDL) were also found in 5000 and 1000 ppm of camphor groups, respectively. Cellular responses to the phytohaemagglutinin-P and 2,4-dinitro 1-chlorobenzene skin test were not influenced by dietary camphor. Humoral responses to secondary sheep red blood cells, avian influenza virus (AIV) and Newcastle disease virus (NDV) immunisations were positively influenced by camphor supplementation, in which greater secondary response to sheep erythrocytes belonged to 750 and 1000 ppm of camphor groups; whereas, diet supplementation with camphor had no significant effect on lymphoid organ weights and heterophil-to-lymphocyte ratio. The greatest AIV antibody titers were seen in groups, which received 1000 and 5000 ppm of camphor (P<0.05) and the values of NDV antibody titers increased with an increase in the camphor consumption. Furthermore, dietary inclusion of 500 ppm of camphor positively decreased coliform populations in the gastrointestinal tract (GIT). In addition, an increase in lactic acid bacteria was also observed in quails, which were fed on the diets containing 750 ppm camphor. Collectively, these data suggest that as a phytogenic feed additive, camphor may effectively act as a modulator of health status (by increasing glucose and HDL), GIT microbiota and immunological responses of the Japanese quail.
Keywords: Japanese quail; blood characteristics; camphor; immune response; intestinal microbiota.