The transport of pheasants from rearing facilities to the final customer is common practice in European countries [18, 20]. The birds are transported over short and long distances in various age categories, and are confronted by a number of stressors during transport, such as capture, placement in crates, loading, transport, and unloading in a new environment. Moreover, the welfare of the animals during transport itself is affected by a large number of other factors, such as temperature, humidity, density of occupation of the transport box and length of transport, as well as time of day and season of the year [2, 19]. The handling of the animal itself can be considerably stressing, as has been shown by a number of studies [16, 21, 22]. This has been confirmed in our study, in which the transport of common pheasants for around three hours resulted in CM levels higher than those before transport. While the pre-transport CM levels ranged from 203.00 ng/g to 275.59 ng/g, their mean post-transport levels increased to as much as 745.35 ng/g in the droppings. A more than threefold increase has also been demonstrated in laying hens transported for one hour [13]. Like the results of our study, another study in laying hens has also shown that increased CM levels lasted more than 36 hours after transport [13].
Sex is commonly given as a factor affecting the resultant concentration of glucocorticoid metabolites in the droppings [23]. For example, the differences exist in CM levels between male and female laying hens5 and between male and female black grouse (Tetrao tetrix) [24]. In our case, differences were recorded in absolute values, with the levels of the CMs measured being higher in males. Statistically significant differences were not, however, demonstrated. Levels of glucocorticoids in the droppings of males and females are influenced by different physiological and behavioural aspects. Higher levels have been shown both in males (e.g. in the domestic chicken) [5] and in females (e.g. in certain mammals) [25]. The resultant faecal CM levels can be affected in certain males with an increased level of androgens circulating in the blood (in elephants during the “musth” period). In females, in contrast, a considerable quantity of circulating glucocorticoids in the blood is connected with “globulin binding sex steroids”, for which reason the overall levels of glucocorticoids may be higher than in males [9, 10]. There are, however, also studies that have, like our study, not recorded any differences in CM levels (such as in the mourning dove) [26]. This may be explained by the fact that the pheasants in our study were 17 weeks old and were not sexually mature (pheasants reach sexual maturity at the age of between 8 and 10 months) and therefore their CM levels were not affected.
The EIA method (first described by Rettenbacher et al. [5]), targeting the antibody against 4-pregnene-17α,21-diol-3,11,20-trione-21-HS, was used to determine the degree of transport stress in common pheasants in our study. This analysis can be used on various species of bird from the gamebird genus (Galliformes) and involves non-commercial EIA analysis developed in the laboratory. Certain studies state that it is also possible to use commercially produced ELISA kits that measure corticosterone for the determination of CMs in bird droppings. Corticosterone itself is not excreted in bird droppings, though the kits are also capable of recording the levels of its metabolites on the basis of cross-reactivity [5]. The entire spectrum of these metabolites has not yet been thoroughly researched. As some studies state, the use of analysis targeting cortisone, as in our study, is the most appropriate as it captures more kinds of metabolites present in bird droppings [5, 7].