Recent Advances in Animal Nutrition in Australia, Volume 15 (2005) 165 Summary The demand for ostrich meat and other products is increasing. The primary problem facing the industry is a lack of information on the nutrient requirements of these birds, particularly neonatal birds. This may be partly responsible for the high mortality of chicks and the lack of expansion of the industry. Knowledge of the development of the ostrich’s anatomy and digestive function is limited. This review collates current knowledge on these aspects and suggests a way forward for the development of ostrich nutrition. Keywords: Digestive physiology, feeding strategies, fermentative digestion, nutritional requirements, ostrich Introduction There is increasing demand for ostrich meat and hides, worldwide. Between 1996 and 2001, there was a six–fold increase in the consumption of ostrich meat. The rising demand for ostrich meat is attributed to the low content of energy, total lipids, cholesterol and saturated fat, and the high content of protein and iron relative to that of beef, veal, pork, lamb, poultry, rabbit and horse meat (de Jong 1994; Fasone and Adamo 2001). However, the development of the industry is hampered by inadequate knowledge of nutritional requirements of this species, particularly those pertaining to the early–life stage. This may be partly responsible for the high mortality rate observed in the neonatal ostrich. Although the adult ostrich is capable of utilizing large amounts of fibre, the ostrich chick may lack the microbial population needed to digest fibre and be unable to grow optimally or to cope with environmental conditions (Schiavone et al. 1999) when fed high fibre diets. Knowledge of ostrich nutrition and digestive physiology could assist ostrich nutritionists to ensure profitable production by formulating diets that are scientifically and economically appropriate for each stage of growth and production. Feedlot production of ostriches for meat, skin and feathers using complete dry–meal diets based on poultry and pig nutritional standards began about 20 years ago in South Africa (Swart and Kemm 1985). Recently, research has been conducted to define the nutritional requirements of this species, but there is still a lack of information on the requirements of the neonatal chick. Knowledge of nutrient requirements for this phase of development is critical because it may alleviate the high incidence of mortality in ostrich chicks. This paper reviews current knowledge on the digestive anatomy of the ostrich in relation to nutrient requirements. Recent research on the development of gastrointestinal function is highlighted to define a direction for research on nutrient requirements of the neonatal ostrich. Digestive anatomy and morphology The ostrich is an avian herbivore that effectively digests plant fibre, specifically hemicellulose and cellulose, which can make a substantial contribution to the apparent metabolizable energy (ME) content of the diet (Swart et al. 1993b). Vertebrates are unable to synthesize the enzymes necessary to digest plant fibre, but many herbivores and some birds have overcome this by hosting a symbiotic relationship with microorganisms in the gut (Fuller 1984). The digestive tract of the ostrich includes the oral cavity and associated organs (beak, tongue, and salivary glands), oesophagus, proventriculus, small intestine, large intestine, rectum, cloaca and associated organs (liver and exocrine pancreas). In contrast to the digestive tract of chickens and turkeys, ostriches have no crop in which to store ingested food. However, ostriches have a relatively large true stomach (proventriculus) and gizzard, which enable them to store large quantities of feed. The ventriculus (gizzard) is a large bivalved structure located immediately caudal to the keel bone. Ostriches are hindgut fermenters and rely on microflora similar to that present in the rumens of other grazing animals for digestion of fibrous diets. The colon comprises 60% of the length of the intestinal tract in the ostrich but only 6% in the domestic chicken (Table 1). Anatomy and digestive physiology of the neonatal ostrich (Struthio camelus) in relation to nutritional requirements P.A. Iji School of Rural Science and Agriculture, University of New England, Armidale NSW 2351, piji@une.edu.au