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/W0.75 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/W0.75perday.

Reindeer and caribou which are polyestrous, undergo estrous cycles of two lengths, a short cycle of 10 to 12 days, and a long cycle of 24 days. The duration of pregnancy in free-roaming animals was found to be considerably longer than in animals reared in captivity, which may be due to prenatal undernourishment. The estimated digestible energy consumed during the late pregnancy of penned animals amounted to about 6000 kcal/day.

The relation between water turnover and milk intake of five reindeer and caribou calves was determined using the tritium dilution technique. The results indicate that mean turnover rates of tritiated water of male calves from birth to 4 weeks of age increased from 1.44 to 1.65 liters per day, and that caloric intake ranged from about 3500 to 4100 kcal/day.

Packed cell volume, hemoglobin, mean corpuscular hemoglobin concentration, reticulocytes, total leucocytes, and plasma protein concentration were measured each week throughout the year for six reindeer and six caribou. Red blood cells (RBC), packed cell volume (PCV), hemoglobin (Hb), and reticulocyte numbers were lower in the reindeer than caribou, whereas the leucocyte concentrations were higher. Activity and excitement, part of the aggressive behavior displayed by rutting caribou, resulted in an increase of PCV, Hb, and plasma protein levels by 21%, 18.5%, and 10%, respectively. In female caribou, about an 8% drop in these value; occurred during estrus. From the fifth month of pregnancy to parturition, PCV, Hb, and plasma protein increased by 17%, 13.5%, and 11%, respectively.

and J. 0. ANVIK. 1976. Effect of digestible energy intake on glucose synthesis in reindeer and caribou. Can. J. Zool. 54: 737-751. Glucose parameters were estimated by multicompartmental analysis after the single injection of [U-'4C]glucose in pen-fed reindeer and caribou. During the rut, the plasma concentration, pool size, space, total entry rate, irreversible loss, and glucose turnover time of male reindeer and caribou declined; all parameters increased significantly after the rut ended and feeding had begun again. In female reindeer and caribou the lowest estimates of glucose pool, space, total entry rate, and irreversible loss were noted during midpregnancy (February-April). During early lactation (May-June) significant increases were noted in total entry rate, irreversible loss, and the plasma concentration of glucose.For non-lactating reindeer and caribou, inflections in relationships between glucose total entry rate and irreversible loss with digestible energy intake were noted at a daily digestible intake of about 195 k~a l l W~.~* (where W0.75= metabol~c body weight); three times more glucose was synthesized per unit digestible energy intake above the polnt of inflection than was synthesized below it. Per unit of protein intake, total entry rate and irreversible loss of glucose for males exceeded that of the females by 4 to 5 mg/W0-75 per minute. In female reindeer and caribou a close correlation was noted between the glucose irreversible loss and total entry rate. Glucose resynthesis was constant at 1.5 mglW0,7S per minute. MCEWAN, E. H., P. WHITEHEAD, R. G. WHITE et J. 0. ANVIK. 1976. Effect of digestible energy intake on glucose synthesis in reindeer and caribou. Can. J. Zool. 54: 737-751.On a estimC Ies param&trcs du glucose par analyse des compartiments apris une injection unique de g l u c~s e~-~~C ] chez des rennes et des caribous gardis en captiviti. Duran! le rut, la concentrationde glucose d a m le plasma. la taille du pool. I'espace glucosique. le taux des entrees totales. la perte it-rkversible et le lauxde remplacement du glucose dlminuent chez les caribous et les rennes miles; tmrq les pmmktres subissent une augmentation significative aprks le rut. au moment ou les animanx recornmencent h ~e nOUTTIT. Chez les femelles, c'est au milieu de la grossesse (fevrier a avril) qu'on enregistre les estimis les plus faibIes du pool, de I'espace gtucosique, du taux den entree5 totales et de la perte irriversible. Au debut de la lactation (mai-.iuin), on enrekstre des augmentations significatives du taux des entrees totales. de la perte irreversible et de la concentration de glucose danr le plasma. Chez l e~ caribous et les renncs qui n'allaitent pas. la relation entre le taux desentrees totdes et la perk irriversible du glucose, d'une part, et I'ingestion d'knergie digestible, d'autre part. subit une inflexion lorsque le total de I'inergle digestible est d'environ 195 kcal/WO 75 (OU W0.75 = le poids mitaboIique du corps); au-dessus du point d'inflexion. il y a trois fois plus d e glucose synthetise pa...