DIURNAL, SEASONAL AND SEX INFLUENCES ON HEART RATES OF AFRICAN GIANT RATS (Cricetomys gambianus, WATERHOUSE) IN THE NORTHERN GUINEA SAVANNAH ZONE OF NIGERIA

Abstract

Heart rate (HR) was measured over a 3-year period in captive African Giant rats (AGRS), live-trapped in Zaria, Nigeria during the harmattan (cold-dry), hot-dry and rainy seasons, as influenced by diurnal, seasonal and sex patterns. The HR showed no significant diurnal changes (P > 0.05) during the hot-dry and rainy seasons, but the morning and afternoon effects differed (P<0.01) during the cold-dry season. Overall seasonal HR differed (P<0.001) among the seasons, with the highest (165.8 0.51 bpm) and lowest (153.1 ± 0.74 bpm) values recorded during the cold-dry and hot-dry seasons, respectively. HR of males (bucks) was lower than that of females (does) during the cold-dry (P<0.0001) and hot-dry (P < 0.01) seasons, but sex difference during the rainy season was not significant (P > 0.05). It is concluded that season, time of day and sex influenced fluctuations in HRS of AGRS, and should be considered during clinical evaluations.