Daily rhythmicity of behavioral responses in donkeys of different age groups during the cold-dry (harmattan) and hot-dry seasons in a tropical savannah

Abstract

Abstract The aim of the study was to evaluate the daily rhythms of behavioral activities of adult, yearling, and foal donkeys during the cold-dry (harmattan) and hot-dry seasons in a tropical savannah. Thirty, clinically healthy free-ranging donkeys, divided into 3 groups of 10 donkeys each according to their age, served as experimental subjects. Behavioral activities of donkeys were monitored bihourly from 06:00 to 06:00 h (GMT +1) during the cold-dry and hot-dry seasons. Application of single cosinor procedure showed that behavioral activities exhibited varying levels of daily rhythmicity in both seasons. Behavioral activities of adult, yearling, and foal donkeys peaked during the afternoon period (13:11-14:45 h) of the photophase of the light–dark cycle during the cold-dry and hot-dry seasons. The diurnal index of activity rhythm showed that donkeys are mostly diurnal animals. During the study period, the percentage time spent on feeding during the harmattan season was higher (P