Effects of restricted feeding on circadian activity rhythms of sheep. A brief report

The purpose of the present experiment was to investigate the impact of timed restricted feeding on the behavioural circadian organization of sheep. For this purpose, total activities of sheep subjected both to 12-h light:12-h dark (12:12 LD) cycle and to periodic food-availability during the dark phase were recorded. When food was available ad libitum, sheep activity was entrained to the 12:12 LD cycle. During the restricted feeding treatment, most activity occurred in the dark. Activity in the dark was confined to the food restriction time and a food anticipatory activity was clearly present. Restricted feeding-entrained activity demonstrated the existence of both food entrainable and food anticipatory activities in sheep, a diurnal mammalian species. Our results represent the first study on the feeding entrainment of behaviour in a ruminant farm species. Furthermore, they allow to plan a deeper analysis concerning the synchronization of circadian oscillators by periodic food access in non-rodent mammals.