Seasonal change of daily motor activity rhythms in Capra hircus

Abstract

To evaluate if seasonal changes in photoperiod and temperature were associated with changes in total daily motor activity we recorded the total daily motor activity of five clinically healthy goats at four different times of the year (vernal equinox, summer solstice, autumn equinox and winter solstice). Goats were housed under natural photoperiod and natural ambient temperature in a 12-m2 sound-proof box equipped with 50 × 100 cm opening window, which allowed natural ventilation. Total motor activity of each goat was recorded by Actiwatch-Mini®, actigraphy-based data loggers that record a digitally integrated measure of motor activity. Our results show the existence of clear seasonal variations in daily activity rhythms in goats, with the highest daily amount of activity during the vernal equinox (769.21 ± 82.56 movements h-1) and the lowest during the winter solstice (401.65 ± 61.82 movements h-1) (P < 0.0001). There was also a change in the amount of motor activity observed during photophase and scotophase through the year (P < 0.0001). The cosine peak (times of the daily peaks), always occurred in the middle of the photoperiods and varied from season to season (P < 0.0001). Our data indicate that daily motor activity of goats varies with season. Key words: Daily rhythm, environmental condition, total activity, goat