Determination of the circadian rhythm in plasma corticosterone and catecholamine concentrations in growing broiler breeders using intravenous cannulation.

This paper describes a fast and simple technique for cannulation of the vena cutanea ulnaris (wing vein) in ad libitum fed growing broiler breeders of 5 weeks of age. Twenty-four hours after cannulation, blood was sampled every 4 h during 24 h. The circadian rhythm in plasma corticosterone and catecholamine concentrations was determined for the first time in growing broiler breeders. During the light period, baseline plasma corticosterone concentrations were higher than during the dark period, and reached the circadian peak at 11:00 h (lights on from 07:00 to 15:00 h). Plasma noradrenaline concentrations were higher during the light period than during the dark period, but there was no pronounced circadian rhythm in plasma adrenaline concentrations. Plasma corticosterone and catecholamine concentrations fell within the same range as previously reported in laying hens.