Metabolizable energy requirements for maintenance and faecal and urinary losses of juvenile harp seals (Phoca groenlandica)

Abstract

Assimilation efficiency of energy in juvenile harp seals was 92.5–95.0% of gross energy intake when fed Atlantic herring and 72.2% when fed shrimp. Faecal energy losses increased directly with intake. Metabolizable energy (ME) ranged from 85.5 to 88.7% of gross energy intake for a diet of herring. Urinary energy losses increased directly with apparent digestible nitrogen intake. Faecal and urinary losses were not affected significantly by feeding frequency. Urine excretion indicated that feeding causes a diuresis, associated with increased energy, nitrogen, and ash excretion. A significant interaction was found for rate of weight change between feeding frequency and energy intake. Seals lost more weight at energy intakes below their maintenance level when fed four meals rather than two meals per day. Differences in rate of weight change with feeding frequency were not observed at other levels of energy intake. Maintenance energy requirements were estimated at 2658 kcal ME daily for seals fed two meals per day and 3514 kcal ME daily when fed four meals per day. Seals required approximately 3 times as much shrimp as herring of high lipid content to meet their energy requirements.

Energy Reallocation during and after Periods of Nutritional Stress in Steller Sea Lions: Low‐Quality Diet Reduces Capacity for Physiological Adjustments

“…During our summer experiment, ME did not decrease significantly for any of the diet groups, meaning there was no overall evidence of energy expenditure sparing during the restriction from thermorégu-lation, activity, and basal metabolism. Counterintuitively, allocation to ME increased after 2 wk of restriction for group H, as has been observed in other species during nutritional stress (Mrosovsky and Sherry 1980;Keiver et al 1984;Ali et al 2003). This increase in energy allocated to ME may have been why animals in group H seemed to release more energy from their body than the actual gross energy deficit (198%, even though it was not significantly greater than 100% ofthe energy deficit; see Table 2).…”

“…When faced with energy restrictions, animals can utilize a range of bioenergetic adjustments including increased digestive efficiencies, behavioral adjustments to reduce activity or thermal costs, decreases in basal metabolism, and changes in grovrth and in foraging effort (Mrosovsky and Sherry 1980;Keiver et al 1984;Worthy and Lavigne 1987;McCarter and McGee 1989;Nordoy et al 1990;Oritsland 1990;Markussen et al 1992;Trites 1999, 2002;Ali et al 2003). During the summer restriction, all animals in our study (independent of diet type) relied exclusively on internal energy reserves to balance their budgets when faced with energy deficits caused by reduced energy intake.…”

“…Changes in ME, particularly increases during nutritional stress, are generally thought to be associated with increases in activity (Mrosovsky and Sherry 1980;Keiver et al 1984;Ali et al 2003), a major component in the energy budget of pirmipeds (Costa and Williams 1999). For example, immature Steller sea lions spend 40%-75% of their time swimming, and mature animals spend 70%-80% of this time in the water in winter (Merrick and Loughlin 1997;Swain and Calkins 1997;Trites and Porter 2002), which represents up to 65% of their daily energy expenditure (Trites and Porter 2002;Winship et al 2002).…”

Energy requirements of Pacific white-sided dolphins (Lagenorhynchus obliquidens) as predicted by a bioenergetic model

“…Pinnipeds consuming a diet of herring or squid have measured digestive efficiencies of~0.90-0.97 (Keiver et al 1984;Fadely et al 1990;Fisher et al 1991;Lawson et al 1997a). We therefore assumed the digestive efficiency of Pacific whitesided dolphins was uniformly distributed between 0.90 and 0.97 (i.e., energy loss was uniformly distributed from 3% to 10% of total energy intake).…”

Feeding habits of harp and hooded seals in Greenland waters

“…Lavigne et al 1985, Keiver et al 1984, which may be app licable in the present context. But again, the allocation to certain regions or seasons is highly speculative.…”