Effect of long-term heat exposure on peripheral concentrations of heat shock protein 70 (Hsp70) and hormones in laying hens with different genotypes

1. The effect of long-term, moderate heat stress (30 to 32°C) on heat shock protein 70 (Hsp70) concentration in mononuclear blood cells and plasma concentrations of 3,5,3'-triiodothyronine (T3) and corticosterone in laying hens was investigated. 2. Three groups of 48 hens each (Ethopian line [Angete Melata, Na], New Hampshire [NH], F1 cross [Na × NH]) were divided into an experimental group (24 each) and a control group (24 each, ambient temperature 18 to 20°C), respectively. All hens were kept in individual cages up to an age of 68 weeks and performance data were recorded. 3. Blood samples were taken from the wing vein of 12 hens from each group at weeks 22, 38, 51 and 65 (12 hens × 3 lines × 2 treatments). Mononuclear blood cells were isolated and Hsp70 concentrations were determined by Western Blot analysis with a monoclonal anti-Hsp70 antibody. T3 and corticosterone were measured with commercially available ELISA and RIA kits, respectively. 4. The moderate heat stress caused significantly increased Hs...