Comparison of three serial blood sampling techniques on plasma hormone concentrations in the laying hen.

Serial blood samples were drawn at 2 hr intervals for 6 hr by either heart puncture (HP), venipuncture (VP), or via a chronic wing vein cannula (WVC) to assess the effects of sampling technique on plasma hormone and hematocrit concentrations. Data for plasma concentrations of corticosterone (B), LH, testosterone (T), progesterone (P4), and the hematocrit (Htc) were analyzed by a split-plot design and analysis of variance making orthogonal comparisons among times and treatments. Results indicate that plasma B was significantly increased and LH and T decreased subsequent to the first sampling in the VP and HP groups compared to the WVC group. In addition, plasma P4 was decreased subsequent to the first sample drawn by HP compared to the WVC group. The Htc was not different between the HP and VP groups; however, a significant time interaction indicates a decrease in the Htc with repeated samplings in both groups. In contrast, for the WVC group, in which red cells were replaced, the Htc measured in the first and last sample was essentially unchanged. Finally, no differences were found in plasma concentrations of B, LH, T, P4, and the Htc when venous blood was compared to arterial blood. It is concluded that blood sampling via a WVC, preadapting the bird to handling, and red blood cell replacement as described herein minimize sampling-induced perturbation in hormone concentrations.