Clinical haematology of the great bustard (Otis tarda).

The haematological parameters of healthy great bustards (Otis tarda L.) have been determined. The values obtained were red cell count (3.0 x 10(12) +/- 0.2 x 10(12/)1), white cell count (33.0 x 10(9) +/- 2.6 x 10(9)/1), haematocrit value (0.51 +/- 0.01 1/1), haemoglobin (13.0 +/- 0.3 g/dl), mean corpuscular volume (178.7 +/- 12.5 fl), mean cell haemoglobin concentration (25.0 +/- 0.6 g/dl), mean corpuscular haemoglobin (42.5 +/- 3.2 pg), differential white cell count: heterophils (22.5 x 10(9) +/- 0.7 x 10(9)/1), lymphocytes (6.0 x 10(9)+/-0.7 x 10(9)/1), eosinophils (2.7 x 10(9) +/- 0.3 x 10(9)/1) and monocytes (1.8 x 10(9)+/-0.2 x 10(9)/1).


INTRODUCTION
The great bustard is an endangered species in Europe. Therefore, all the efforts aimed at the protection of this species must be supported.
In the past few years, we have seen an increase in the numbers of these birds taken to the Clinic of Internal Medicine due to pathological problems. For this reason we have studied the haemophysiological parameters, with the purpose of establishing reference values.

MATERIALS AND METHODS
Thirty-six clinically healthy birds were chosen at random without chemical immobilization, from the Las Seguras. The birds were between 1 and 11 years of age. The animals have been kept on a 124-acre farm. We cannot accept, therefore, that they were in absolute captivity. The birds were fed on insects and other casual seasonal food.

RESULTS AND DISCUSSION
The data obtained were subjected to a simple analysis of variance carried out to determine the effect of sex. The results are given in Tables 1 and 2. No protozoa or microfilarine were seen in blood smears. The mean number of erythrocytes differed between males and females (P < 0.005). Similar differences have been described by Hunsaker et al. (1964) for the goose {Anser anser), Sturkie (1967) for the chicken (Gallus domesticus) and Nirmalan & Robinson (1971) for the quail {Cotumix cotumix). The mean value of 3.0 X 10 12 RBC/1 is the same as the one obtained by Balasch et al. (1974) for different avian species.
The haemoglobin values for the species were 13.0 g/dl, similar to those obtained by other authors (Balasch et al, 1973(Balasch et al, , 1974(Balasch et al, , 1976 for birds such as the brown pelican (Pelicanus occidentalis occidentalis), imperial eagle (Aquila heliaca) or Andean condor (Vultur gryphus). However, the observed mean haemoglobin value was larger than that found by Alonso et al. (1990) in free-living young great bustards, 11.7 g/dl. This may reflect the differences in age. Adult birds usually have higher values as demonstrated by Tanaka & Rosenberg (1954) and Deaton et al. (1969) in the chicken (Gallus domesticus), by Hunsaker et al. (1964) in the goose (Anser anser) and by Atwal et al. (1964) in the quail (Cotumix cotumix).
The haematocrit value for great bustards, 0.51 1/1, is greater than that reported by Alonso et al. (1990) of 41% in free-living young great bustards. The mean MCV value obtained in our experiment, at 178.7 £1, is somewhat larger than that reported by Alonso et al. (1990) in free-living young great bustards (166.6 fl), and very much higher than that quoted for the domestic fowl (Gallus domesticus) by other authors (Abou-Ashour & Edwards, 1972). In contrast the mean MCMH value of 25.0 g/dl, was less than that observed by Alonso et al. (1990) of 28.5 g/100 ml and considerably smaller than the mean value found by Jones & Johansen (1972) in several avian species such as domestic chicks (Gallus domesticus), wild ducks {Anas platyrhynchos) and wild turkeys (Meleagris gallopavo). This difference might be due, in part, to different centrifugational forms being employed in different studies.
The leucocytes values observed (Table 2) are similar to those obtained by Lucas & Jamroz (1961) for domestic chicks (Gallus domesticus) and by Venkataratnam & Clarkson (1962) for the peacock (Pavo cristatus). Nevertheless, the value of WBC count is much larger than that found by Alonso et al. (1990) in free-living young great bustards (11,000 WBC/mm 3 ). This difference may be due to the fact that Alonso et al. (1990) examined young birds in their experiment, while all birds in this paper were adults.