Semi-domesticated Herds Research Articles

Mismatch between calf paternity and observed copulations between male and female reindeer: Multiple mating in a polygynous ungulate?

In polygynous systems, such as that exhibited by reindeer Rangifer tarandus, mate choice can be difficult to disentangle from male intrasexual competition because male behavior may constrain female choice. Multiple mating may provide an avenue for female mate choice, though it is difficult to identify using behavioral estimators alone. Molecular techniques address this issue by affording ecologists an opportunity to reassess mating systems from a genetic perspective. We assessed the frequency and possible explanations for multiple mating in reindeer using a genetic approach to determine the success of observed copulations in a semi-domesticated herd in Kaamanen, Finland. Behavioral and genetic data were synthesized with population characteristics over a 7-year period to test the hypothesis that, if present, polyandry in reindeer is driven by sexual harassment from sub-dominant males. We observed multiple mating in 42% of females, with as many as 60% exhibiting multiple mating in certain years. We found no evidence that multiple mating resulted from sexual harassment by sub-dominant males, suggesting that it is likely a deliberate strategy among females. Conversion rate of copulations into paternities varied with male size, with smaller males more likely to experience mismatch than larger males. Female preference for larger males persisted despite the occurrence of multiple mating, possibly suggesting a mechanism for cryptic post-copulatory selection. We suggest further research to delineate the possible influence of cryptic post-copulatory selection and multiple mating to defend against infertility in exhausted males.

Experiences from 40 years of muskox (Ovibos moschatus) farming in Norway

Experiences from the management of a semi-domesticated herd of muskoxen, mostly on an island outside Tromsø (~70º N; 19º E), over a period of 40 years have been collected, and data on husbandry practices, reproduction, diseases and longevity are presented and discussed.

Dystocia in Formosan sambar deer (Cervus unicolor swinhoei) in semi-domesticated herds

Over a nine-year period (2000 to 2008), 22 instances of dystocia and 50 normal fawnings in Formosan sambar deer (Cervus unicolor swinhoei) hinds from semi-domesticated herds were investigated. The majority...

Parasite intensity and fur coloration in reindeer calves – contrasting artificial and natural selection

1. In reindeer, the variation in fur coloration is higher in semi-domesticated than in wild populations. This difference might result from impacts of natural enemies acting on conspicuously coloured individuals with higher intensity in natural than semi-domesticated populations. 2. While predator pressure is rather similar for wild and semi-domesticated populations, semi-domesticated reindeer are less impacted by parasitism due to endectocidic treatment. In this study, we estimated the intensity of warble flies in different reindeer colour morphs in a large sample of untreated calves from multiple semi-domesticated herds in northern Norway. 3. We found that lighter coloured reindeer calves have higher intensities of warble fly larvae than darker ones. This is associated with a decrease in body mass, and may hence influence subsequent fitness of the animals. 4. The high intensity of parasites in white calves implies that they are either more exposed or less resistant to parasitic infections. In either case, parasitism by warble flies appears to be a proximate cause driving coloration of reindeer towards a reduced variability in natural populations.

The reproductive performance of female Formosan sambar deer ( Cervus unicolor swinhoei) in semi-domesticated herds

This study documented the reproductive performance of 210 adult female Formosan sambar deer (FSD, Cervus unicolor swinhoei) from four semi-domesticated deer herds in Taiwan. An extensive analysis of 525 reproductive records from 2000 to 2008, including the conditions of estrus, gestation, and parturition was conducted. The mean ± S.E.M. lengths of the estrous cycle, gestation, and fawning interval were 18.2 ± 0.5 d ( n = 56), 258.6 ± 0.3 d ( n = 160), and 369.9 ± 2.3 d ( n = 122), respectively. Hand breeding was performed between June and December ( n = 494), with the majority (93.1%) occurring between July and October ( P < 0.05). Fawning occurred from February to September ( n = 318), and most frequently (83.0%) between April and June ( P < 0.05). Pregnancy rate per mating in FSD hinds was 64.4%. There was a 1.3:1 male-to-female ratio at birth ( P < 0.05) among 320 fawns, and only two cases of twinning (0.63%). The postnatal mortality rate was 6.6% (21/320), and the mortality rate in fawns before weaning did not exceed 8% on any farm. Fecundity was enhanced by high pregnancy rates and high offspring survival rates. This study provides baseline information on reproductive performance of FSD, which should be valuable to veterinarians and deer industry personnel for management of FSD on farms in subtropical countries.

Genetic variability in Norwegian semi-domestic reindeer (Rangifer tarandus

Polyacrylamide gel electrophoresis was used to examine genetic variation in semi-domestic herds of reindeer. Rangifer tarandus L. Samples of liver, skeletal muscle and blood from four different herds in southern Norway were sampled. The electrophoretic expression indicated 45 presumed loci, 34 of which were considered usable for population genetic surveys. Genetic variability was observed at 8 loci and the proportion of polymorphic loci varied between 0.118 and 0.176 by the 99% criterion for polymorphism. The within herd heterozygosity (H) varied between 0.017 and 0.030 with a mean of 0.022. The allele frequency distribution indicates little genetic heterogeneity, and less than 3% of the genetic variation in the polymorphic loci is attributable to differences between herds. No heterozygote deficiency was observed, suggesting that no inbreeding occurs.

Ovarian and placental production of progesterone and oestradiol during pregnancy in reindeer

We obtained uterine and peripheral venous plasma, and samples of luteal and placental tissues from 2- to 7-year-old, Eurasian mountain reindeer ( Rangifer tarandus tarandus) from a free-living, semi-domesticated herd in northern Norway in November 1995, and February and March 1996. In November, ovarian venous blood was also collected from four animals. Plasma samples were assayed for progesterone and oestradiol. The tissue samples were examined by light and electron microscopy, steroid dehydrogenase histochemistry, and northern blot analysis for RNAs for 3β-hydroxy-steroid dehydrogenase (3β-HSD) and P450 (side chain cleavage (scc)). Peripheral blood was taken from non-pregnant females in the same herd on the same dates. Peripheral progesterone concentrations in pregnant reindeer (3.4±0.5 ng/ml, n=8) clearly exceeded those in non-pregnant animals (0.40±0.14 ng/ml; P<0.0004, n=10) but oestradiol levels were only marginally higher in pregnant (6.0±0.7 pg/ml) than in non-pregnant (4.8±0.5 pg/ml; P=0.35) reindeer at the stages examined. In pregnant animals, peripheral progesterone and oestradiol concentrations rose slightly between November and March but the differences did not reach significance (progesterone, P=0.083; oestradiol, P=0.061). In November, progesterone concentrations in the ovarian vein (79±15 ng/ml) greatly exceeded ( P<0.03) those in the uterine vein (10±4 ng/ml) which in turn exceeded the levels in the peripheral blood (2.8±0.4 ng/ml; P<0.29). Oestradiol concentrations were slightly but significantly ( P<0.05) higher in the ovarian (20±3 pg/ml) than the uterine vein (13±1 pg/ml) and, in turn, greater ( P<0.03) than in peripheral blood (4.6±0.4 pg/ml). All samples of luteal tissue consisted exclusively of normal fully-differentiated cells and stained intensely for 3β-HSD. Isolated groups of placental cells also stained strongly for 3β-HSD. RNA for P450 (scc) and 3β-HSD was abundant in all corpora lutea and lower concentrations of P450 (scc) were present in the placenta. 3β-HSD RNA in the placenta was below the limit of detection. We conclude that the corpus luteum remains an important source of progesterone throughout pregnancy in reindeer but that the placenta is also steroidogenic.

Reproduction in female reindeer

Reindeer are either wild or kept under very extensive farming systems. They are seasonal breeders, with mating coinciding with the decreasing photoperiod in the autumn, and with calving in the spring. Little is known regarding the factors that influence reproduction in reindeer or of their reproductive physiology. Studies carried out to date have mainly focused on issues related to the population dynamics of wild populations and semi-domestic herds, and to a limited extent on the reproductive physiology of the female. Nor is much known about reproductive disorders and their medical treatment, or of the possibilities to manipulate or control reproduction by the use of hormones. Modern reproductive techniques such as artificial insemination and in vitro fertilisation, maturation and transfer of embryos have so far received scant attention. In the future, it is possible that reindeer under certain conditions might be kept in more intensive production systems. Limited access to high-quality winter pastures and increased demands for productivity have resulted in artificial feeding becoming a common practice in various reindeer herding areas in Scandinavia. In efforts to enhance the productivity of reindeer herds, attention has been focused on factors affecting reproduction in the female and survival of the offspring. Further knowledge on these issues seems necessary when developing strategies for optimalization of meat production in domestic herds and the harvesting of wild populations. This paper puts a broad focus on various aspects of reproduction, including factors influencing the fecundity of reproductively active females. In order to understand these effects it is important also to have a basic understanding of the reproductive physiology of these animals.

Reproduction and Mortality of Finnish Semi-Domesticated Reindeer in Relation to Density and Management Strategies

We assessed the effects of management strategies during 1960-73 relative to strategies used during 1974-87 on the reproduction and mortality of 56 semi-domesticated herds of Finnish reindeer (Rangifer tarandus tarandus). During 1960-73, reindeer fed exclusively on natural forage growing on their range, and reindeer were harvested mostly as adults. These strategies were modified starting in 1974 to include supplemental feeding in the southern part of the Finnish reindeer range and calf harvesting throughout the range. We found significantly higher calf/female ratios, lower mortality, and less variation in both calf/female ratios and mortality during 1974-87 than during 1960-73. These changes occurred in spite of increased animal density. Coefficients of variation in calf/female ratio and mortality were negatively correlated with the prevalence of mature spruce forests, which are rich in arboreal lichens. Mean calf/female ratio and mortality rate depended on reindeer density only in the southern region during 1960-73. During 1974-87 these did not depend on density in any region. Within herds, calf/female ratio did not depend on density in most cases (98%), while in the later period the relationship between calf production and density was positive in some cases (25%). Mortality depended more often on density during the earlier (46% of herds) than the later (23% of herds) period. Calf harvesting influenced mortality more than supplemental feeding and virtually freed reindeer from density-dependent limitations. Supplemental feeding was used to compensate for deterioration of range resulting from overgrazing and logging of mature forests rich in arboreal lichens.Key words: reproduction, mortality, density dependence, reindeer, Rangifer tarandus, management, Finland