Energy requirements for maintenance and faecal and urinary losses of the grey seal (Halichoerus grypus)

Assimilation efficiency of gross energy (±SD) in juvenile and adult grey seals fed Atlantic herring was 92.6 ± 2.1%. Metabolizable energy (ME) was 82.7 ± 4.8% of gross energy intake. Faecal energy losses increased directly with energy intake and urinary energy losses increased directly with apparent digestible nitrogen intake. Maintenance energy requirements were estimated at 4215 kcal (1 cal = 4.1868 J) ME daily for both juvenile and adult seals, equivalent to daily food intakes of 3.0–3.2 and 1.5% of body weight for juvenile and adults, respectively.