Growth In Reindeer Research Articles

Allocating Protein to Reproduction in Arctic Reindeer and Caribou

Reindeer (Rangifer tarandus tarandus) and caribou (Rangifer tarandus granti) use body stores (capital) and food intake (income) for survival and reproduction. Intakes of low-nitrogen (N) food declined in winter and increased in spring (51-83 g dry matter kg(-0.75) d(-1)). Reindeer calved before regaining food intake, whereas caribou calved 28 d later. Body N was conserved by minimizing oxidation of amino acid N to urea. Maternal protein stored from early winter was used for 96% of fetal growth in reindeer but only 84% of fetal growth in later-birthing caribou. Both subspecies rely on maternal body protein for 91% of the protein deposited in the neonate via milk over the first 4 wk. All females lost body protein over winter, but lactating females continued to lose protein while nonreproductive females regained protein. Net costs of lactation above maintenance were greater for N (110%-130%) than for energy (40%-59%). Large fat stores in reindeer spare body protein from oxidation in winter, whereas in caribou, less fat with the same body protein favors migration when food is inadequate. The resilience of Rangifer populations to variable patterns of food supply and metabolic demand may be related to their ability to alter the timing and allocation of body protein to reproduction.

Forage Quality and Reindeer Productivity: Multiplier Effects Amplified by Climate Change

ABSTRACTWe investigated the effects of experimental manipulations of snowmelt on the flowering phenology and forage chemistry (digestibility and nitrogen concentration) of tussock cottongrass (Eriophorum vaginatum) on the Seward Peninsula, Alaska. Early snowmelt accelerated reproductive phenology by 11 days, and resulted in higher floral digestibility both early and late during inflorescence development. Nitrogen concentrations of inflorescences in late snowmelt plots were initially the highest among treatments, but decreased nearly 40% during inflorescence development. Thus, changes in climate that lead to changes in snow cover can alter both the timing of flowering and chemistry of Eriophorum and, consequently, its value as reindeer and caribou forage. We then used published relationships between forage chemistry and body weight gain of reindeer (White, 1983) to model the possible effects of altered forage chemistry on food intake and growth in reindeer. Model output shows that reindeer foraging on Eriophorum inflorescences may increase digestible dry matter intake twofold by selectively foraging on early-emergent inflorescences. The multiplicative effects of forage quality and food intake result in a near doubling in the rate of weight gain during this critical early spring period. Such increases in body weight gain have potentially great consequences for reindeer at both individual and population levels.

Characteristics of first-antler growth in reindeer and their association with seasonal fluctuations in steroid and insulin-like growth factor 1 levels

Growth and development of the pedicles and first antlers were monitored in seven reindeer (Rangifer tarandus tarandus) calves (three males, four females) from birth to 1 year of age. Calves were weighed, blood was sampled, and antler observations and (or) measurements were taken on the day of birth and days 2, 4, and 7 and then at weekly intervals for the remainder of the year. Prior to measurable growth, the frontal lateral crest was carefully palpated for evidence of pedicle initiation, starting on the day of birth. Calves were born between April 8 and 26, 1994. Pedicle initiation occurred in all reindeer by day 7. Velvet skin first appeared when calves were 4-6 weeks old, when estimated pedicle height was 3.5 ± 0.9 cm (mean ± SD). Antler growth in both sexes followed a sigmoidal pattern, producing a mean antler length of 33.5 ± 4.2 and 46.7 ± 13.8 cm in females and males, respectively. Antler growth was complete by week 18 in females and week 21 in males. Velvet cleaning was associated with a significant increase in plasma testosterone levels in males and estradiol-17beta (but not testosterone) levels in females. Insulin-like growth factor 1 levels were significantly higher in males than in females and were positively correlated with the period of most rapid antler growth in both sexes. Casting occurred between March 14 and April 17, when steroid levels were at a minimum, and was immediately followed by growth of the second antler.

Characteristics of first-antler growth in reindeer and their association with seasonal fluctuations in steroid and insulin-like growth factor 1 levels

Characteristics of first-antler growth in reindeer and their association with seasonal fluctuations in steroid and insulin-like growth factor 1 levels

Extreme Seasonal Growth in Arctic Deer: Comparisons and Control Mechanisms

Synopsis. Arctic ungulates have the capacity to voluntarily restrict growth to times of the year of predictable high quality seasonal herbage abun? dance. The constraints ofthe arctic environment mean that not only must the timing of this growth seasonality be accurate but growth rate must be maximised for a short period of time. It is known that daylength is a critical cue for the timing of seasonal rhythms of growth; a manipulated photoperiod of 16L:8D stimulates out of season growth in reindeer during winter and this growth is associated with an increase in the plasma levels of insulin like growth factor 1 (IGF 1). In contrast a manipulated pho? toperiod of 8L: 16D delays the spring rise in growth. There is good evidence from a boreal cervid, the red deer, that the number of hours of day influences growth rate also and this is associated with IGF 1. Thus day? length may have a dual role in growth seasonality, timing and amplitude. Although the mechanisms underlying the timing of rhythms by daylength are partly understood a putative role for daylength in controlling the rate of an event is a new concept.

Early maternal investment and growth in reindeer

I studied whether females in a herd of semidomesticated reindeer (Rangifer tarandus) in Finland invest more heavily in male than in female offspring and whether the mother's body size and condition have different effects on growth rates of male and female offspring. The results did not provide evidence of different preweaning investment in male and female offspring. Proportional mass loss of breeding females during calving was greater when the calf was male than when it was female, but change in mass between consecutive autumns did not depend on the sex of the calf. In general, the growth of male and female calves depended in approximately similar fashion on maternal characteristics, but amongst the male calves only, the growth rate from birth until the following November depended on the mother's change in mass the previous winter. Mass loss of parturient females was inversely related to mass loss during pregnancy. Females that experienced heavy mass loss from November until postcalving gained the most mass before the following November. Winter food supplementation probably led to large body masses and a low mortality rate of calves and might have masked differences in reproductive costs associated with producing male and female calves.

Growth and relationship of live weight to body measurements in semi-domesticated reindeer (Rangifer tarandus tarandus L.)

Estimation of live weight from measurements of body dimensions is useful in many management activities with domestic animals. In present study live weight was measured from 2932 female and 1037 male semi-domesticated reindeer (Rangifer tarandus tarandus L.) during different seasons in 1969-85. The age of reindeer varied between 1 day and 14 yrs. Back length (along back from second spinous process to base of tail) and chest girth (just behind front legs) were taken also from 1490 female and 510 male reindeer. The growth of reindeer from birth to adulthood was cumulative consisting of a rapid weight accretion during summers followed by a weight loss or stasis during winters. The mathematical analyses of the growth based on exponential solutions gave average values for growth of female and male reindeer. Body weight of females increased until the age of 4.5 yrs and that of males until the age of 5.5 yrs. During winter and spring body weight of hinds decreased 10 to 15 kg and that of stags 30 to 50 kg in different age groups. Significant linear regressions were found between live weight and back length (r = 0.809 and 0.892), live weight and chest girth (r = 0.860 and 0.872) and live weight and combined body measure (back length + chest girth) (r = 0.877 and 0.941) and live weight and body volume (r = 0.905 and 0.954, respectively) in female and male reindeer. Exponential regressions gave, however, the best estimations of live weight with combined body measure.

Relationships between body weight and body measurements of reindeer

Genus Rangifer populates the northernmost habitat of the Cervidae and shows alterations in body weight, skeletal growth rate and nutritional state with the marked seasonal changes in its environmental conditions. Body weight and measurements have long been the standard criteria for evaluation of growth in domestic animals. Body weight has been also used most by workers to describe growth and body size in reindeer and caribou. The numerical values of the weight to length ratios of skeletal bones are not so much expressions of growth rates, but rather of the growth patterns of these bones. Body measurements and ratios are useful taxonomic criteria and are used in Rangifer systematics. The results indicate that body ratios, such as shoulder height/foreleg length and shoulder height/back length are independent of body size and thus primarily of genetic origin (Nieminen & Helle 1980). The objective of this study was to measure the apparent ageand sex-related growth and the seasonal changes in body weight and body measurement in semidomesticated reindeer. During different seasons in 1969 85 the body weight was measured in Kaamanen experimental station and in different herding cooperatives from 2932 reindeer females ranging from birth to 14 years of age and from 1037 males ranging from birth to 10 years of age. General physical development was measured after the first 4 months of life by chest circumference and back length taken from 1490 females and 510 males. The mean birth-weight of female calves was 5.0 kg. Male calves weighed 0.3 kg more. After the first 6 months of life, body weight of reindeer calves followed alternating periods of positive and negative growth. The body weight increased until the age of about 3.5 years in females and until the age of 5 7 years in males. In winter both young and adult females lost between 13 and 19% of their prime autumn weight. However, the percentage of prime autumn weight lost by males in winter increased from about 10% the first year to 33% at maturity. The fluctuations of body weight are largely attributed to the seasonal depostition and mobilization of fat reserves. Growth of reindeer ceased in winter because of either an inherent physiological rhythm or a decline in nutritive value of the diet, or both. The body weight of female reindeer was highly correlated with the back length (r=0.809) and chest circumference (r=0.860). Similar relationships were also found for male reindeer (r= 0.892 and 0.872, respectively). However, the best relationships were noted between the body weight and the joint measure (back length + chest circumference) in female (r=0.877) and male reindeer (r=0.941). Similar relationships have been shown for domestic species. There were some differences in relationships between the body weight and the joint measure in young and over 3-year-old females and males. Differences were also found in these relationships during autumn and winter.