1. The effects of
chromium picolinate and
biotin supplementation alone and in combination on performance, carcase characteristics,
malondialdehyde (MDA),
vitamin C,
vitamin E,
glucose and
cholesterol levels were evaluated in Japanese quail exposed to high ambient temperature. 2. Two hundred and forty quails (10d old) were assigned randomly to 4 dietary treatments at room temperature (22 degrees C; thermoneutral, TN) or ambient (34 degrees C for 8 h/d; heat stress, HS). Both TN and HS were fed either on a basal (control) diet or the basal diet supplemented with 400 microg of Cr/kg (Cr group), 0.5 mg of
biotin/kg of diet (
biotin group) or both (Cr +
Biotin group). 3. Supplementing the diet of heat-stressed quails with
chromium picolinate improved live
weight gain, feed intake, feed efficiency and carcase traits.
Biotin supplementation during TN and HS conditions did not have any beneficial effects on
body weight gain, feed intake, feed efficiency or carcase traits. 4. Either in combination or alone,
chromium picolinate increased serum concentrations of
vitamins C and E, but decreased MDA,
glucose and
cholesterol concentrations in birds kept at high ambient temperature. There was no difference in
vitamins C and E and MDA concentrations between birds given
chromium picolinate and birds receiving
chromium picolinate plus
biotin, while
glucose and
cholesterol levels were significantly lower in all groups. The lowest concentrations of
cholesterol and
glucose were found in the combination group under both TN and HS conditions. An interaction between diet and temperature was detected for
glucose and
cholesterol concentrations. 5. Excretion rates for
zinc,
iron and
chromium were lower in TN groups than in the corresponding HS groups. Supplementing diet with
chromium picolinate and
chromium picolinate plus
biotin decreased excretion of minerals while
biotin alone did not effect excretion of minerals. 6.
Chromium supplementation, but not
biotin supplementation, attenuated the decline in performance and
antioxidant status resulting from heat stress.