Reindeer bulls are difficult to manage and dangerous to handlers during the rutting period. Progesterone agonists have been used anecdotally in the field to favorably influence behavior, but effects on reproductive signaling have not been determined. The objective of this study was to determine the effects of Depo-Provera (medroxyprogesterone acetate) on neural activity in the amygdala of reindeer bulls in the early (n = 4) and full (n = 4) rut. Treated bulls (n = 4) were injected with a single injection of Depo-Provera (400 mg i.m.) approximately 2 wk before rut was initiated. Control bulls were untreated. Bulls were exsanguinated and brains collected. Neural activity in the amygdala was determined using c-fos immunohistochemistry. Neural activity did not differ by treatment (P ≥ 0.5), collection period (P ≥ 0.5), or their interaction (P ≥ 0.3) in the medial and cortical amygdala nuclei. A treatment × time interaction (P = 0.009) was observed in the central amygdala. The amygdala nuclei are interconnected allowing for integration of sensory stimuli with a direct connection between the medial amygdala and the olfactory bulb. The central amygdala is responsible for alerting, fear, and initiating a state of arousal towards nonspecific stimuli in the surrounding environment. In wildlife, the central amygdala has a role in recognizing threats in the environment such as predators. During the rut, bulls normally have a decreased sense of fear and elevated aggressive behavior with Depo-Provera treatment seemly able to diminish that aggression. Although it is unlikely that this observed change in neural activity fully explains the decreased aggressive behavior noted in bulls treated with Depo-Provera, neural networks of aggression include the amygdala. It is possible that further changes in c-fos activity will be noted in other areas of the brain known to be necessary for processing social cues. Bulls treated with Depo-Provera maintain sexual interest and have offspring. Depo-Prevera increases the neural activity within the central amygdala and may partially account for their altered aggressive behavior during the rut.

Poor calf production and ill thrift in 3-4 mo olds are common limiting problems in raising and maintaining captive muskoxen (Ovibos moschatus). Acute onset of a rapidly progressing enteritis and septicemia in neonatal calves (2-7 days of age) caused by Escherichia coli not normally considered pathogenic in domestic animals is a serious problem in many captive muskoxen facilities. Serum immunoglobulin G (IgG) levels, total protein, albumin, and globulin levels in captive periparturient muskox females and their neonatal calves were compared with levels found in other species in which these parameters have been well described. Results showed that all females in the study had IgG present in their serum (mean = 1,232.14 mg/dl, SD = 178.34 mg/dl, as measured via radial immunodiffusion). Calves were probably born agammaglobulinemic or hypogammaglobulinernic. IgG levels quickly rose in calves after initial colostrum intake to levels similar to those seen in other domestic ruminants. Our results suggest that passive transfer of immunity in muskoxen is similar to what is reported in domestic livestock and that reference ranges from domestic cattle may be used to assist interpretation of serum IgG levels in muskoxen. In addition, the positive relationship between serum protein and globulin levels with serum IgG levels is similar to that reported for Holstein cattle and thus provides a useful indicator of passive transfer in muskoxen.

Reindeer have been classified as intermediate feeders and muskoxen as grazers based on differences in digestive morphology and consumption of fibrous plants. We hypothesized that the digestive morphology of young (<2 months) reindeer and muskoxen anticipates transitions in diet and determines the feeding strategy of each species at adulthood. We compared structural morphology and rates of cell division in the rumen, abomasum, duodenum and liver of reindeer and muskoxen as neonates (1 day old), during the transition from milk to forage (30–60 days old) and in adults (>7 yr). Development in utero provided the neonate with a functioning mucosa of the gastric abomasum and duodenal mucosa with high surface enlargement for digestion and absorption of concentrated milks. Transition to forage was preceded by changes in ruminal papillae structure that increased surface area and likely contributed to active fermentation by 60 days of age. The abomasum also increased in acid-secreting parietal cells during the transition to forage, which may enhance digestion of plant and microbial proteins. Rates of cell division also indicated a sustained differentiation of tissue structure during the transitional period. Young arctic ruminants expressed digestive structures that preceded full function, which indicated the ultimate feeding strategy of each species. For example, the rumen of young muskoxen had thick cornified epithelia and muscle layers that would provide ruminal mucosa with better protection from fibrous abrasion and enhance motility of bulky diets. Conversely, young reindeer had more complex papillary shapes in the rumen and more foliate villi in the duodenum, indicating a greater absorptive capacity of these structures than in muskoxen. Ontogenetic programs, therefore, play the primary role for digestive development of reindeer and muskoxen and determine the nutritional strategies of adults.

Reindeer are polygynous ruminants that breed when plant growth declines in the Arctic. We studied seven males (2 years and older) in two herds with a total of 34 females to describe the costs and consequences of mating or rut. Body mass declined between September and November and did not recover through winter even though food was available ad libitum. Dominance did not affect body mass or any correlate of mass loss, indicating similar costs of rut among males. Males lost 34% of ingesta-free mass in 77 days of rut, which corresponded to depletion of 23% body protein and 78% body lipid. Water flux, plasma insulin, and plasma thyroxine were minimal 23 days after the peak in body mass, indicating low food intake. Maximum plasma testosterone and cortisol also followed peak mass and coincided with the death of two males from acute infections. Loss in body protein did not increase the ratio of urea to creatinine in plasma. Increased variance in plasma osmolality and urea during mass loss indicated altered homeostatic control during rut. Mating compromises survival of males through reduction of body reserves, food intake, and maintenance of tissues. These adverse effects may be the consequence of selection for large body size and aggression in a highly variable competition for mates.

The transfer of trace minerals between mother and fetus may be critical for survival of young ruminants especially among species at high latitudes, which gestate during a long winter and grow through a brief summer. We examined the distribution of copper and metalloproteins (ceruloplasmin and metallothionein) in muskoxen and their fetuses, three times during gestation. Hepatic levels of copper were high in mothers (179 microg g(-1) whole tissue) and did not change through gestation, whereas fetuses accumulated large reserves of Cu (>300 microg g(-1)), likely stored in proteins such as metallothionein, during the last third of gestation. The effect of fetal Cu demands on the pregnant female was tested by supplementation of Cu by subcutaneous injections of Cu gluconate (30 mg Cu/week) during pregnancy. Maternal copper supplementation did not significantly increase hepatic Cu in newborns (412 microg g(-1) for supplemented vs. 303 microg g(-1) for unsupplemented neonates), probably because the diet was already adequate in copper (14 microg g(-1) dry matter). Ceruloplasmin activity declined in pregnant muskoxen that had not received injections of Cu and suggested increased systemic demands for copper during late gestation. Supplies of Cu to the fetus could be limited either by low levels of Cu in the maternal liver, or in the maternal diet during late winter when fetal gains in mass and liver Cu are greatest.

Muskoxen (Ovibos moschatus) consume fibrous plants that grow rapidly over the short Arctic summer. We studied responses of eight castrated male muskoxen to a diet of grass hay and mineral supplements during spring, autumn, and winter. Animals gained body mass in spring (239 +/- 39 kg) as body fat content increased from 26% to 38% of ingesta-free mass in winter without changes in lean mass and protein. Intakes of dry matter (DM) increased by 74% between spring and autumn as digestible energy increased from 554 to 923 kJ kg(-0.75) d(-1) during mass gain. Digestibility of cellulose (72% - 76%) was not affected by increasing food intake between spring and autumn but was reduced to 65% in winter. Digestibility of nitrogen compounds was 61%-66%, even though intake increased by 134% between spring and autumn. Excess dietary nitrogen from hay and supplements increased urea concentrations in plasma and urine. High loads of solutes such as potassium did not affect plasma or urinary osmolality but were associated with increased rates of glomerular filtration and urinary excretion. Low intakes of sodium from grasses may limit intake and digestion during summer, but high food intakes can support deposition of nitrogen, calcium, magnesium, copper, and zinc in body tissue even when dietary concentrations are low. Seasonal increases in digestive and metabolic functions allow muskoxen to rapidly accumulate energy and nutrients in body tissue during the short season of plant growth.

We compared wild muskoxen (Ovibos moschatus) on Banks Island (Northwest Territories, Canada) with captive animals maintained on grass (Bromus sp.) hay and supplemental minerals. We measured copper (Cu) in liver, whole serum, and deproteinated serum (unbound Cu) as well as serum activity of the Cu-enzyme ceruloplasmin. Unbound serum Cu concentrations did not change with season in captive animals (n=53). Ceruloplasmin activity was similar between seasons in females but elevated in males during breeding in autumn. Increasing concentrations of Cu in whole sera were mainly associated with protein whereas unbound Cu predominated at low concentrations of whole serum Cu. Ceruloplasmin activity and serum Cu concentration were linearly related to liver Cu in female muskoxen. Measures of copper status in females were lower in the wild (n=19) than in captivity (n=16): 8 vs. 160 ug Cu·g−1 of whole liver; 0.67 vs. 1.15 μg unbound Cu·ml−1 whole serum and; 22 vs. 33 IU·l−1 ceruloplasmin activity. Bioavailability of Cu may limit the population on Banks Island especially when density of animals is high. The wide range of hepatic Cu concentrations in muskoxen indicated accumulation of Cu without apparent ill effect in captive animals. Hepatic storage of Cu may allow wild muskoxen to contend with low and fluctuating availability of Cu in small foraging areas at high latitudes.

Post-natal availability of copper may affect survival of arctic ruminants such as muskoxen (Ovibos moschatus), because neonates must develop rapidly before their first winter. We hypothesized that supplemental injections of Cu for lactating females would increase Cu in milk and in circulation within their offspring. Milk was low in Cu (<4 μg Cu·g–1dry matter) but was not affected by Cu supplementation through peak lactation. Muskoxen are born with high concentrations of Cu in the liver but low activity of the Cu enzyme ceruloplasmin in serum. Levels of serum ceruloplasmin and Cu increase as neonates mature, reaching adult levels in late summer, but this transition coincides with poor growth and diarrhea. Reserves of Cu established in utero are likely depleted as metabolic processes mature and as young make the transition from a milk-based to a forage-based diet. Therefore, availability of trace minerals in utero and in autumn forages may influence the growth, immune function, and survival of young muskoxen in their first year.

Northern ungulates must establish trace mineral reserves when forage is available in spring and summer to sustain biochemical activities through the long winter. Copper (Cu), zinc (Zn) and iron (Fe) reserves were measured in the serum, digestive tract, liver, and kidney of six male caribou and reindeer (Rangifer tarandus) fed a complete pelleted ration. Dry matter content and absolute amounts of Cu, Zn and Fe were highest in the liver. Digesta contents of Cu and Zn were greatest in the rumen but dry matter concentrations were greatest in the cecum reflecting the high levels of Cu and Zn in the diet. Serum ceruloplasmin (an oxidase containing Cu) activity was related to liver copper in captive reindeer and caribou (P < 0.05, r2 = 0.82) during spring and winter but not during the rut. Michaelis-Menten kinetics of ceruloplasmin were measured in sera from captive reindeer, muskox (Ovibos moschatus) and moose (Alces alces) (n = 3/species). Maximum velocities (VMAX) were 42, 20 and 9 (IU·L−1); kM were 0.38, 0.55 and 0.62 (mM) for muskox, reindeer and moose respectively. Wild caribou (n = 3) from the Teshekpuk herd and moose (n = 3) from the Colville River had lower VMAX (7 IU·L−1) and higher kM (1.9 mM) than their captive conspecifics. These kinetic parameters probably reflect differences in ceruloplasmin structure between species as well as differences in tissue reserves between populations within each species. Serum ceruloplasmin activity and kinetics can provide a non-lethal alternative to direct measures of hepatic Cu reserves in wild and captive populations. However, the method requires validation for the effects of sex, season, development and disease in each species.

The muskox colony at the Large Animal Research Station, started in 1979, totaled 22 individuals before calving in 1988. Between 1988 -1994 cows of breeding age have been maintained on either a high plane (HP) or low plane (LP) of nutrition, and as far as possible, female offspring are kept with their mother's group. During this time the population has increased from 22 to 43 animals (25 females and 18 males). Fifty-four calves were born with an overall sex ratio of 52:48 (male:female). When partitioned between the 2 nutritional planes the sex ratio was HP 45:55 and LP 62:38. The calf/cow ratio was 0.83 in 1988 and 0.86 in 1994. The LP group accounted for most of the variability in pregnancy rate, primarily through delayed puberty and breeding pauses. Calf mortality was due mainly to abortions, stillbirths and neonatal death (n=12), 7 deaths occurred between 2 weeks and 1 year of age. All stillbirths and abortions (n=4) and 6 of 8 neonatal deaths affected calves of HP cows. Thirteen adults died, 4 males were loaned to other facilities and 2 new calves were added.

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.

Seasonal levels of LH, FSH, testosterone (T), estradiol, progesterone (P), and prolactin (PRL) were determined in the plasma of five adult bulls, and five barren and four pregnant cows of Alaskan reindeer (Rangifer tarandus), which were sampled every 3 weeks for 54 weeks. The male reproductive axis was sequentially activated; LH peaked in May-June (2 ng/ml), FSH in June (51 ng/ml), and T in September (11.8 ng/ml). LH levels in females reached a maximum in both groups at the end of August (the beginning of the rut). Seasonal variation in FSH was minimal in pregnant cows, but exhibited one elevation (41 ng/ml) in barren ones in November. T levels in cows remained at barely detectable levels. The decrease of T values observed in both groups in December and March was not significant. PRL peaked in May in cows (135 ng/ml pregnant, 140 ng/ml non-pregnant) and in June in bulls (92 ng/ml). Estradiol was highest in bulls in the rut (August), in non-pregnant cows in January and in pregnant cows in April, shortly before parturition. P levels in the pregnant cows rose from September and peaked (9 ng/ml) shortly before parturition in April. In the non-pregnant females P values increased and decreased several times before peaking (5 ng/ml) in March. In the males, the variation of T and estradiol levels correlated relatively well with the antler cycle but in the females the variation of neither estradiol, progesterone nor T appeared to be related to mineralization or casting of antlers.

Yersinia pseudotuberculosis is a gram-negative bacteria known to cause a variety of disease conditions in many species and is a major cause of mortality in farm and captive wild ungulates (Obwolo 1976, Mackintosh and Henderson 1984). It has not been as well documented in wild populations. Yersinia pseudotuberculosis was first confirmed in wild muskoxen on Banks Island in 1986 (Blake et al 1991). A l l age and sexes suffered Yersinia mortalities but bulls accounted for at least 75 % of the mortalities in 1986 (Blake et al 1989). The objectives of this study in 1987-90 were: 1) Locate carcasses and determine the cause of death of all muskoxen in the study area. 2) Estimate total numbers of muskoxen in the study area and classify a sample of the age and sex structure. Muskox carcasses and skeletal remains were located by aerial and ground surveys in the study area in July or August. Age, sex if discernible, location, and the position (sternal, side) of the carcass were noted. A full necropsy was done using standard field technique on intact carcasses, to assess physical condition at time of death and possible cause of mortality. Any evidence of rauma prior to death was noted. Suspected Yersinia mortalities generally had good fat stores, died in the summer, and if recent, had obvious enteritis, enlarged lymph nodes or septicemia. A loop of intestine, a mesenteric lymph node and intestinal swabs (placed in Phosphate Buffered Saline (PBS)) were taken for subsequent culturing for the presence of bacteria. Overwinter mortalities were determined by the absence of a solid marrow core, position (sternal, fetal, spread out) of the carcass and the state of decomposition in some cases. Any new carcasses since the previous year's survey were examined as .potential Yersinia mortalities which occurred after we left the study area and were added to the yearly totals. Suspected Yersinia mortalities accounted for 88 % of 72 carcasses found in 1987 but only 23 % of 109 carcasses found in 1989 (Table 1). The estimated Yersinia mortality rate was 8-10 % of the 1987 summer population, while in 1989 and 1990 the rate was only approximately 2-4 % of the summer population. The data for 1987¬ 1990 suggests that adult males are still the age/ sex class most affected by Yersinia while starvation affected all age classes but predominantly young and old age classes (Table 2). The expression of this disease in muskoxen may be an indication of stress associated with a high density population and the high contamination levels in some years. Densities of muskoxen in the area varied from 2.7 to 3.2 muskoxen per k m 2 (excluding calves) in the summer. Adult bulls are the most susceptible to infection

Sixty-seven muskox (Ovibos moschatus) carcasses, 53 skeletal remains and two sick muskoxen were seen during an aerial survey of the Thomsen River region, northern Banks Island, Northwest Territories, Canada in late July 1986. Complete necropsies were performed on 29 muskoxen estimated to have died within the previous 3 to 5 days. Twenty were diagnosed with acute yersiniosis due to Yersinia pseudotuberculosis serotype 1B and were in excellent body condition. A diagnosis could not be made on seven animals due to marked autolysis; however, these muskoxen also were in excellent body condition. The remaining two were aged, emaciated muskoxen. This report describes the first occurrence of yersiniosis in free-ranging muskoxen and the first documentation of large scale mortality due to this disease in a free-ranging population of wild ungulates.

The skull of a mountain sheep (Ovis canadensis cremnobates) exhibiting osteoporosis was recovered from San Diego County, California. This specimen also exhibited lateral asymmetry of the cranium and rostrum, malocclusion of molars, and mandibular asymmetry. Investigators are cautioned about potentially confusing lesions associated with chronic frontal sinusitis with lesions of osteoporosis in mountain sheep. To our knowledge this is the first report of osteoporosis in this species.