Hawassa University, Department of Animal and Range Sciences, P.O. Box 05, Hawassa, Ethiopia; Leibniz Institute for Farm Animal Biology (FBN), Research Unit Muscle Biology and Growth, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany; Martin-Luther University Halle-Wittenberg, Institute of Animal and Nutritional Sciences, Theodor-Lieser-Str. 11, D-06120 Halle (Saale), Germany
Melesse, A., Hawassa University, Department of Animal and Range Sciences, P.O. Box 05, Hawassa, Ethiopia; Maak, S., Leibniz Institute for Farm Animal Biology (FBN), Research Unit Muscle Biology and Growth, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany; Von Lengerken, G., Martin-Luther University Halle-Wittenberg, Institute of Animal and Nutritional Sciences, Theodor-Lieser-Str. 11, D-06120 Halle (Saale), Germany
The objective of this study was to evaluate the effects of genotype x temperature interactions on hormonal heat stress indicators and performance traits. Two-hundred forty female one-day-old chicks were randomly assigned to a completely randomized design in a 5×2 factorial arrangement with 5 genotypes (Naked-neck, Na, from Ethiopia; New Hampshire, NH; Lohmann White, LW and F 1 crosses of Na with NH and LW) and 2 ambient temperatures (thermo-neutral, 18-20°C; heat stress, 30-32 °C). Blood samples were taken from 12 randomly selected birds per genotype and ambient temperature at 22, 38, 51 and 65 weeks of age. Levels of corticosterone (CS) and 3,5,3'-triiodothyronine (T 3) were determined in blood plasma. Heat stress effects on egg production traits were most severe in LW and NH, least severe in Na and Na × LW, intermediate in Na × NH. Plasma T 3 level was significantly reduced by 27.9% in heat stressed genotypes. Plasma CS increased by 12.6% in heat exposed genotypes. However, inconsistent responses of CS and T 3 levels were observed at different ages. The Na and their F 1 crosses demonstrated relatively better thermotolerance than LW and NH hens. Levels of plasma T 3 hormone might be considered as indicator of long-term heat stress in hens.
3,5,3'-Triiodothyronine; Corticosterone; F 1 crosses; Genotype x temperature interaction; Heat stress; Naked-neck chicken