Assessment of stable areas for young ostriches based on physiological stress parameters

Commercial ostrich farming continues to develop globally, however, there is a lack of scientific research on ostrich welfare related to husbandry conditions. To assess needed stable size, young ostriches were kept in three groups of 8 animals on 20 m² (i.e. 2.5 m²/animal), 40 m² (i.e. 5 m²/animal) and 80 m² (i.e. 10 m²/animal) of stable space with access to 2500 m² of pasture for each group. Feather corticosterone (fCort) as well as blood heterophil/lymphocyte (H/L) ratio, creatine kinase (CK), aspartate aminotransferase (AST) and uric acid (UA) were evaluated at 6, 9, 12 and 15 months of age as indicators of chronic stress. fCort dropped over time in groups in larger stables while fCort of ostriches on 2.5 m²/animal remained near starting levels (p = 0.0599). H/L ratio, AST and CK yielded no differences between groups. UA plasma concentrations were significantly higher in the group on 2.5 m²/animal (p < 0,01). During a period when birds had to be stabled because of avian influenza restrictions, fCort and H/L ratio showed an upward trend though this was overshadowed by individual differences. Our findings suggest a negative effect on ostriches kept on 2.5 m²/animal but no additional benefits for ostriches kept on stables of 10 m²/animal over those on 5 m²/animal. For further assessment of stable sizes ethological studies are necessary.