Seasonal changes in the energy and nitrogen intake in reindeer and caribou

The relation between energy intake and body weight of reindeer and caribou are summarized. The results indicate that caloric intake was 35–45% lower in winter than during the summer growth period. The relation between heat production and body weight also exhibited a cyclical pattern. Heat production per unit of metabolic weight decreased by 25% (mid-August to mid-November). From calorimetry studies, the relative proportions of protein and fat deposition from weaning to 12 months of age were estimated. The amount of digestible nitrogen required for N equilibrium amounted to 0.462 g N/W 0.75 per day, a value comparable to those reported for cattle and sheep. The estimated metabolizable energy requirement for maintenance of a 70-kg reindeer in winter amounted to 5.5 Mcal/day, or about 200 kcal/W 0.75 perday.