The performance of farmed ostrich chicks in eastern Australia

A prospective observational epidemiological study was undertaken in the south-eastern region of Queensland in eastern Australia to collect accurate information on the performance of farmed ostriches, and to identify the most important constraints facing on-farm production. This paper (the third in a series of three) focuses upon the performance of 394 chicks that hatched on 11 farms in this region from eggs laid between 1 July 1993 and 30 June 1994. Each chick was observed from hatch until dying, leaving the farm of origin or reaching 4 months of age (whichever occurred first). A total of 60.8% of the chicks survived to 4 months of age, with an overall crude mortality rate during the period of observation of 14.0 deaths per 100 chick-months at risk. The most common causes of death were the development of a lower-limb deformity (most frequently tibiotarsal rotation which accounted for 36% of all chick deaths), 'fading chick syndrome' (13%), and salmonellosis (11%). Only 83% of the chicks remained free of tibiotarsal rotation during the period of observation. This condition was generally first detected in chicks between 2 and 10 weeks after hatch, and the median survival time following diagnosis was 10 days. 'Fading chick syndrome' mainly affected chicks less than 3 weeks of age and did not appear to spread in a contagious manner. Chicks died following infection with Salmonella typhimurium on only one farm. Chick-level factors affecting survival during the 4 months following hatch were examined using the Cox proportional hazards regression model. After accounting for farm-level effects, risk factors for death or euthanasia during the first 4 months following hatch included the weight of the chick at hatch, and the development of tibiotarsal rotation. The need of the industry-wide development and adoption of objective measures of productivity is discussed, and some relevant measures are proposed.