Native immunity and oxidative traits of growing rabbits

The evaluation of animal welfare through innate immunity (Serum Bactericidal Activity - SBA, Hemolytic Complement Assay - HCA, lysozyme) and the antioxidant status of the body (Reactive Oxygen Substances - ROS and Antioxidant Power of plasma, AP) offers a reliable prognostic and diagnostic tool. The aim of the present study was to investigate trends and correlations between some traits of innate immunity and the oxidative status of fattening rabbits at different ages. Blood samples from 120 New Zealand White fattening rabbits at 45, 55, 65, and 75 d of age were collected and analyzed. The results showed that SBA did not have a normal distribution because of numerous 0 values. Data distribution was normal when only SBA > 0 values were considered. Lysozyme (mean value 27.19 ug/mL) and HCA (mean value 50.84 CH50%) had stable trends at different ages and showed a tendency that was comparable to that obtained in other animal species. On the contrary, SBA (mean value 42.15%) showed an unexpected positive correlation with lysozyme (P<0.001) and a negative correlation with HCA (P≤0.001). Oxygen free-radicals are involved in the pathogenesis of several diseases and oxidative stress alters immune competence. In this experiment, ROS and AP showed mean values of 0.60 mmol H2O2and 421.67 μmol HCIO, respectively. In this context positive correlation coefficients between oxidative status traits and immune traits (P<0.001) were found, although at a very low level; and surprisingly, only ROS and SBA did not show any significant correlation. In this study it emerged that, even in the absence of evident pathologies, the immune and oxidative traits of fattening rabbits could be affected by environmental stress (weaning, cage, neighbors).