Abstract Young rabbits (Oryctolagus cuniculus) are only nursed for 35 min every 24h. They show a circadian increase in activity in anticipation of this, which is entrained by suckling. Our aim was to determine whether serum and liver metabolites show diurnal fluctuations which could act to regulate this circadian pattern. Stomach weight, liver glycogen and serum metabolites were measured every 3h in 7- to 8-day-old pups when normally nursed (up to 24h after suckling) and fasted (up to 48h after suckling). The results suggest: