2.4. Behavioral effects of propofol
Twenty seven chicks were randomly divided into three
groups of nine birds each. The chicks were injected with
either physiological saline solution (control) or with propofol
at 0.5 and 1 mg/kg. These doses of propofol were below
the ED50 of propofol for the induction of sedation and they
did not produce overt signs of sedation in the chicks. The
3-min open-field activity of each chick was monitored 1 h
after the propofol injection as described before [32]. The
dimensions of the open-field box were 60 × 60 × 30 cm,
and its arena was divided into 16 equal squares with
50 g of wheat grains scattered evenly on the surface. After
the open-field activity test, each chick was subjected to
tonic immobility test which is considered a kind of fear
response in birds [34,36] and the duration of immobility
was recorded.