Metabolic rates and thermoregulatory responses were studied in adult moose (Alces alces) exposed to various ambient temperatures during winter and summer. Resting energy expenditures followed a marked annual cycle with a maximum (940 kJ kg body weight−0.75 d−1) during spring – early summer and minimum (430 kJ kg body weight−0.75 d−1) during winter. The heat increment of feeding associated with a pelleted ration was 6–9 kJ kg body weight−0.75 h−1. The energy cost of standing was 4.2 kJ kg body weight−0.75 h−1, an increment of 25% over the lying posture. Although piloerection was observed between −25 and −30 °C, metabolic rates did not increase. In contrast to their cold tolerance, moose were easily heat stressed. During winter, moose increased respiration rates when ambient temperatures rose above −5 °C. Resistance to heat load was greater for standing moose during summer; respiration rate increased above 14 °C and open-mouthed panting began at 20 °C. Energy expenditure and heart rate followed a similar rise with increasing ambient temperature.

Intake, rumen digesta pool sizes, ruminal digestion rates, passage rates of liquid and particle pools and faecal particle-size distrubutions of grass, browse and lucerne diets were compared in ruminally fistulated moose, wapiti and cattle. For each diet, ruminal digestion rates (nylon bag technique) were similar for the three ruminants. Intakes, rumen digesta pool sizes and passage rates varied among species and higher rates were associated with passage of larger faecal particles. However, it was not possible to simply rank the three ruminants as representative grazers (cattle), browsers (moose) and mixed feeders (wapiti) since intakes, passage rates and rumen pool sizes interacted with diet and season. Contrary to expectation, digestible dry matter intakes of each species were not greatest for their respective typical diets.

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Forages used by moose, Alces alces, in the aspen‐dominated boreal forest were studied to determine seasonal changes in digestibility (nylon bag technique) and chemical composition. Digestibility of all forage classes increased to 70% during spring and summer with the presence of new growth and declined to a low of 30% with plant maturation and dormancy. Mean protein contents during these periods were >20% and <7%, respectively. Nutritional quality of herbaceous forages peaked earlier and higher than that of woody plants in spring but quality declined earlier and reached slightly lower levels in late winter. Cell wall composition of grasses, sedge, and foliage varied seasonally and was correlated with forage digestibility. In multiple linear regression models, hemicellulose, cellulose, and lignin content of browse, grass, and sedge provided significant predictions of digestibility.