Abstract: The study investigated the effect of ethanol extract and ethyl acetate soluble fraction of Calyces of Hibiscus sabdariffa (C.H.S) on hyperthermia, hematology and behaviour of laying hens during the hot-dry season. Experimental layers administered orally ethanol extract or ethyl soluble fraction of C.H.S at doses of 200 mg kg 1, respectively, maintained a normal rectal temperature value and lower Heterophil Lymphocyte (H L 1) ratio. They did not exhibit any stressful behaviours of excess water intake, wing fluffing or panting. The control layers not administered with any extract had higher (p< 0.01) rectal temperature values, H L 1 ratio and exhibited stressful behaviours, including 10% mortality rate. The correlated results between the atmospheric temperature and rectal temperature and behaviour of panting were significant and negative (p< 0.05) in experimental layers. In control layers the correlation was significant and positive (p< 0.05). The results showed that C.H.S reduced or eliminated the effect of heat stress in the layers. The calyces might have direct or indirect inhibitory and immuno-modulating effects on the nervous system, apart from its antioxidant and antibacterial property. Hence, could be used in ameliorating the negative effect of heat stress on laying hens predominantly reared under hot climatic conditions.
N.S. Minka , A. Fayomi and J.O. Ayo , 2007. Protective Influence of Calyces of Hibiscus sabdariffa Against Heat Stress in Laying Hens During the Hot-Dry Season. Research Journal of Poultry Sciences, 1: 7-11.