Japanese quails (n ¼ 240; 10 day-old) (Coturnix coturnix
japanica) obtained from a commercial company were used
in the study. The experiment was conducted in Veterinary
Control and Research Institute of Elazig, Turkey. The
birds were randomly assigned, according to a 24
factorial design, to eight treatment groups consisting of
ten replicates of three birds. The first factor was the
temperature. The birds were kept at an environment controlled
room at either 22 1C with the relative humidity
of 57% (Thermoneutral, TN groups) or at 22 1C for 16-h
and 34 1C with the relative humidity of 42% for 8 h/day
(09.00 am–05.00 pm; Heat stress, HS groups). The second
factor was lycopene supplementation (Roche, Levent-
Istanbul) to the diet at level of 0, 50, 100 or 200 mg of
per kg of diet. At both temperatures, birds were fed either a
basal diet (TN-C and HS-C) or the basal diet supplemented
with 50, 100 or 200 mg of lycopene/kg of diet. Lycopene
was incorporated into the diet in the form of an oily form