Survey of plasma and liver mineral concentrations and enzyme activities in ostriches (Struthio camelus) under farmed conditions in New Zealand

AIM: To generate clinical biochemical data to aid diagnosis of suboptimal performance in ostriches farmed under pastoral systems in New Zealand. METHODS: Blood and liver samples were sought from three categories of bird, viz 3-12-week-old chicks, 7-12-month-old growers, and from breeding hens, managed under pastoral conditions on farms in several locations in New Zealand. Concentrations of the minerals Ca, PO4, Mg, Na, K, Cu and Zn, activities of the enzymes gamma-glutamyl transferase (GGT), creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST), and concentrations of total protein (TP) and uric acid and vitamin E in plasma and Se in whole blood were determined from four flocks of chicks, two flocks of growing and one flock of breeding birds. Concentrations of Cu, Fe and vitamin B-12 were determined from liver samples from chicks and growing birds. Bodyweight was recorded at the times of blood-sampling, where this was feasible. RESULTS: It proved impossible to obtain blood samples by venepuncture of the radial vein from chicks <3 months of age. Plasma concentrations of minerals, with the exception of K, which were higher, were within the normal range observed in the literature for ratite species. Activities in plasma of AST and CK were almost double, and those of LDH similar, to those in the literature for ostriches. There was considerable variation in activities of the enzymes between farms, but no association with growth performance. Concentrations of Cu in plasma were lower and in liver were higher than would be expected in farmed ruminants. Though hindgut fermenters, the birds maintained concentrations of vitamin B-12 in plasma and liver at least comparable to those observed in ruminants. CONCLUSIONS: Collection of blood samples by venepuncture via the wing in ostrich chicks younger than 3 months of age is difficult and unlikely to prove viable for routine diagnostic purposes. Clinical biochemistry data on mineral nutrients in ostriches farmed in New Zealand are similar to those in the literature from South Africa, but AST and CK are higher, and may be normal and a reflection of the high growth rates of the musculoskeletal system.