Possible applications of oxidative stress evaluation in blood of avian species: a preliminary study

In physiological conditions, an equilibrium between pro- and anti-oxidant factors exists; when the former exceed the capacity of their removal/inactivation, Oxidative Stress (OS) occurs [1]. The OS level in blood of selected bird species was assayed, by measuring the Plasmatic Antioxidant Activity (PAT – mmol/L ascorbic acid), and the oxidative plasmatic potential (D-ROMs – mmol/L H2O2); the OS Index (OSI) was then obtained (D-ROMs/PATx1000). In this preliminary study, blood samples were collected from 18 healthy chickens (Gallus gallus domesticus), sampled during usual health monitoring (9 from industrial and 9 from rural organic farming), and from 18 clinically healthy wild birds (Pica pica), captured as part of an ornithological study (authorized with ISPRA Prot. 8093/T-A31 of 02/21/19 and Region ER Det. 3751 of 01/03/19). For OSI test, blood was analysed using FRAS-5 analytical system (H&D); furthermore, a haematological evaluation was carried out with a haemocytometer (Natt & Herricks solution staining), and on blood smear (Diff-Quick staining) for differential count. Statistic evaluation was performed by Mann-Whitney test, and values were expressed as means±SD. In G. gallus, OSI was significantly higher (P=0.011) in subjects from intensive farming (14.7±7.10) than in those bred in rural conditions (5.64±10.32). In P. pica group mean OSI value was 8.14±4.61; in this species, a possible correlation between WBC count and OS was found, since OSI values were significantly higher (P=0,0073) in subjects with WBC>20x103/dl with respect to those with WBC<20x103/dl. Obtained results suggest the occurrence of higher OS levels in chickens bred in intensive conditions, compared to rural farming, which could be related to management methods and productivity levels. In addition, in P. pica the higher OSI values measured in subjects with WBC>20x103/dl may indicate a correlation between OS level and immune response, as previously observed [1]. Collectively, present data open up good prospects for the application of OSI measurement both in avian medicine and in animal welfare monitoring; moreover, a possible utility of this technique in the field of ecopathology could be suggested, since previous evidence exists about indirect monitoring of pollution levels through the evaluation of OS in bioindicator species [2,3,4]. References 1. Birben et al. 2012, World Allergy. Organ. J., 5(1), 9-19. 2. Holt & Miller 2010, Natur. Edu. Knowl. 3(10). 3. Costantini & Møller 2008, Funct. Ecol., 22(2), 367-70. 4. Salmón et al. 2018, Sci. Total Environ., 622, 635-43.