Factors on farms in eastern Australia associated with the development of tibiotarsal rotation in ostrich chicks.

ABSTRACT

OBJECTIVES: To determine the incidence of tibiotarsal rotation (TTR) in ostrich chicks and to identify factors on farms associated with the development of TTR. DESIGN: A cross-sectional study using a personal interview. PROCEDURE During a single visit to 31 farms, data were collected about a defined cohort of chicks, and about farm-related factors that may be associated with the development of TTR. Farms were categorised for TTR status according to the proportion of the chick cohort that survived to 10 weeks of age without developing TTR. Chick performance was measured using descriptive epidemiological methods and univariable analyses were conducted to identify unconditional associations between TTR status and farm-related factors. RESULTS: Ninety-six of 931 ostrich chicks from 21 (68%) farms developed TTR during the first 10 weeks following hatch. Lower limb deformities were the most common cause of death in chicks between 3 and 10 weeks of age. On seven (23%) study farms, where less than 87% of young chicks survived to 10 weeks without developing this condition, TTR was considered a serious problem. Twelve farm-related factors were associated with farm TTR status, including eight chick-related variables (aspects of nutrition, pen design and management) and four farm-related variables (related to the number of veterinary visits, farm location, number of rainy days and the person most closely involved with chick raising. CONCLUSION: The results confirm a continuing problem of young chick wastage in eastern Australia. TTR was an important cause of mortality in farmed ostrich chicks during the first 10 weeks after hatch. The factors that producers could address to reduce the incidence of TTR include pen design, access to water and nutrition.