Seasonal and nutritional effects on serum proteins and urea concentration in the reindeer (Rangifer tarandus tarandus L.)

Immunosenescence patterns differ between populations but not between sexes in a long-lived mammal

In animals, physiological mechanisms underlying reproductive and actuarial senescence remain poorly understood. Immunosenescence, the decline in the ability to display an efficient immune response with increasing age, is likely to influence both reproductive and actuarial senescence through increased risk of disease. Evidence for such a link has been reported from laboratory animal models but has been poorly investigated in the wild, where variation in resource acquisitions usually drives life-history trade-offs. We investigated immunosenescence patterns over 7 years in both sexes of two contrasting roe deer populations (Capreolus capreolus). We first measured twelve immune markers to obtain a thorough identification of innate and adaptive components of immunity and assessed, from the same individuals, the age-dependent variation observed in parasitic infections. Although the level of innate traits was maintained at old age, the functional innate immune traits declined with increasing age in one of two populations. In both populations, the production of inflammatory markers increased with advancing age. Finally, the adaptive response declined in late adulthood. The increasing parasite burden with age we reported suggests the effective existence of immunosenescence. Age-specific patterns differed between populations but not between sexes, which indicate that habitat quality could shape age-dependent immune phenotype in the wild.

Some effects of handling reindeer during gatherings on the composition of their blood

1. The effect of gathering reindeer on the composition of the blood was studied in female reindeer and their calves herded in northern Finland. Blood samples were taken in summer at three gathering places, under differing conditions and in autumn at the same places during gatherings which lasted for longer than 2 days. These were compared with samples taken from little-disturbed animals during winter.

2. Measurements were made of concentrations of glucose and lactate in whole blood and of urea, calcium, sodium, potassium and magnesium in serum, together with serum creatine phosphokinase (CPK) and glutamine oxalacetic transaminase (GOT) activities.

3. Gatherings affected nearly all the blood parameters studied. In summer the temperature during separation seemed to influence glucose and lactate concentrations. The duration of the gathering and the distance the animals were driven clearly affected serum GOT and urea values.

4. During the long autumn gathering serum urea concentration increased about eight-fold in 2 days accompanied by a simultaneous decrease in serum calcium.

5. Serum CPK and GOT activities were higher during the summer and autumn than during the winter. Serum CPK and blood glucose concentrations were higher in young calves than in adult females.

Papillar Morphology of the Rumen of Forest Reindeer (Rangifer tarandus fennicus) and Semidomesticated Reindeer (R. t. tarandus)

The papillar morphology of the ventral and dorsal rumen of the wild forest reindeer (Rangifer tarandus fennicus Lönn.) and semidomesticated reindeer (R. t. tarandus L.) was studied in October and November 1996. The morphological measurements which were carried out were: the lengths of the papillae, the number of the papillae per square centimetre, the cross-sectional area and perimeter of sections cut from the middle of papillae. From these measurements mean papillar volume, areal papillar volume, mean papillar (epithelial) surface area, areal papillar surface and surface enlargement factor were calculated. No differences in these measurements between ventral and dorsal walls of the rumen were evident. The semidomesticated reindeer had longer papillar perimeters, larger mean and areal papillar surface areas, larger mean papillar volumes, and a larger surface enlargement factor in the ventral rumen than did forest reindeer. This may be a result of differences between feeding habits, the semidomesticated reindeer preferring a diet including more plants rich in carbohydrates e.g. lichens, which has resulted in a high production of volatile fatty acids and thus stimulation of papillar growth.

Variation of plasma protein parameters in four free-ranging reindeer herds and in captive reindeer under defined feeding conditions

Plasma total protein (TP), albumin (ALB) and globulin (GLOB) concentrations and albumin/globulin ratio (A/G) were analysed from blood samples collected from free-ranging reindeer (Rangifer tarandus tarandus) herds at varying times of year. The same parameters were followed in nine captive reindeer with varying protein and energy intake. Variation in the blood constituents of free-ranging reindeer was analysed in relation to different extrinsic and intrinsic factors and compared to findings from captive animals, allowing the analysis of effects of protein and energy intake. There was large overall variation in TP, ALB, GLOB and A/G ratio in the free-ranging animals, ranging between 36-110 g/L, 18-59 g/L, 17-59 g/L and 0.5-2.1. The variation between months and years was significant for all variables except the A/G ratio, where no year effect was noted. Increase in live body mass was associated with a small significant increase and pregnancy with a small significant decrease in all dependent variables, except for the A/G ratio. Age did not have a significant effect on any of the blood constituents when body mass was included in the same model. In captive animals, feeding lichens with low protein content was related to a significant decline in TP, ALB and GLOB, but not in the A/G ratio, whereas feeding commercial ration increased plasma TP, ALB and GLOB significantly. Extrinsic factors such as season and year explained majority of variation in the blood constituents of free-ranging reindeer, whereas body mass, pregnancy and age had only a minor influence. It is concluded that plasma TP and ALB, and to a lesser extent GLOB and A/G ratio may serve as nutritional biomarkers of reindeer.

Body condition in Svalbard reindeer and the use of blood parameters as indicators of condition and fitness

Body condition is an important determinant of ecological fitness but is difficult to measure in field studies of live animals. Live mass and subcutaneous fat are often used as proxies for body condition and related to fitness. We investigated the relationship between blood-chemistry parameters and live mass and back-fat thickness and assessed their usefulness as predictors of ecological fitness in a wild arctic ungulate population, Svalbard reindeer (Rangifer tarandus platyrhynchus). Female reindeer were sampled in late winter between 1995 and 2002 and concentrations of blood parameters were related to subsequent survival and successful calving. There was marked annual variation in all blood parameters, live mass, and back-fat thickness, reflecting variation in weather and food availability. At the individual level, variation in blood-parameter concentrations was not closely related to variation in live mass or back-fat thickness, instead reflecting shorter term nutritional status. Blood parameters could therefore provide useful additional information, enhancing the predictive power of fitness models based on live mass. The urea:creatinine ratio significantly improved adult survival models, while β-hydroxybutyric acid and creatinine concentrations were significant predictors of calving success. The applications for blood parameters in ecological investigations look promising and should be tested more widely in other field studies.

Plasma urea, creatinine, and urea: creatinine ratio in reindeer (Rangifer tarandus tarandus) and in Svalbard reindeer (Rangifer tarandus platyrhynchus) during defined feeding conditions and in the field

Variation in plasma urea and creatinine concentration and plasma urea:creatinine ratio (U:C) were studied in semidomestic free-ranging reindeer (Rangifer tarandus tarandus) on the Norwegian mainland, in wild Svalbard reindeer (Rangifer tarandus platyrhynchus), and in captive reindeer maintained either on a lichen-based diet or a protein-rich concentrate to investigate whether these parameters could be used as indicators of the nutritional status of reindeer. In the mainland animals, plasma creatinine concentration was high in winter and early spring and decreased by two-thirds toward the summer. The overall range in mean plasma creatinine concentration (+/-SE) was from 90+/-1.26 to 280+/-2.88 micromol/L. Mean plasma urea concentration (+/-SE) varied from 2.46+/-0.10 in winter up to 17.44+/-0.29 mmol/L in summer and autumn. Month of sampling explained 65% and 90% of the variation in plasma urea and creatinine concentrations, respectively, indicating that seasonality in the diet had the greatest influence on these parameters. Reindeer given lichens as the only feed showed an increase in plasma creatinine and a decrease in plasma urea concentration. Food restriction caused a temporary elevation in urea level but had no significant effect on plasma creatinine concentration. The slight effect of energy intake on urea and creatinine levels was supported by the fact that severe undernutrition in the Svalbard reindeer population had only a small effect on plasma urea and creatinine levels. Protein-rich pellet feed increased plasma urea from around 3 mmol/L to above 10 mmol/L and reduced creatinine concentrations to less than 100 micromol/L, suggesting that the protein content of forage is an important determinant of these blood parameters. Mean U:C ratio (+/-SE) in plasma varied from 8.9+/-0.28 to 120.8+/-1.88. Ratios above 20 appeared when protein intake was low and energy intake was restricted or when protein intake was high. Low ratios occurred when protein intake was low but energy intake adequate. Plasma urea and creatinine concentrations and the U:C ratio showed complex dynamics that were affected by both season and the protein and feed intake. We conclude that they appear to be difficult to interpret as single measures of nutritional status of reindeer.

Effects of immobilization with medetomidine and reversal with atipamezole on blood chemistry of semi-domesticated reindeer (Rangifer tarandus tarandus L.) in autumn and late winter

Blood chemistry was studied in 8 adult female reindeer, of which 5 were pregnant. Half of them received only medetomidine (150 micrograms/kg i.m.) and half of them medetomidine and atipamezole (750 micrograms/kg) in March. Three weeks later the drug regimens were reversed. The same procedure was carried out during the next September and October. Seasonal differences in pretreatment values could be seen in serum urea, phosphorous, and cholesterol, with the highest concentrations during the autumn; and creatinine, ASAT, ALAT, and CK values, which were higher in the non-pregnant reindeer in late winter. Their low-protein and low-energy diet during the winter explains most of the differences. Increased enzyme activities in serum indicate decreased membrane stability of certain organs in late winter, possibly due to nutritional deficiencies. Treatment effects could be seen in several parameters. The increase in blood glucose and decrease in serum FFA were most probably due to alpha 2-adrenoceptor activation, which inhibits insulin release and lipolysis. These effects were partly or totally inhibited after treatment with the antagonist atipamezole. The earlier increase in serum CK and ASAT activities in those receiving atipamezole can be explained by increased tissue perfusion due to atipamezole itself and the fact that these animals stood up and began to move much earlier than did those which received medetomidine only. A significant decrease in serum Na+, K+, Cl-, Pi, cholesterol, total Ca, and total protein concentration observed during the first 10 to 40 min of the medetomidine sedation could be explained by possible haemodilution and diuresis. More effective metabolism of medetomidine in autumn could explain the shorter recovery times of reindeer receiving only medetomidine and most of the differences in treatment effects between the seasons: faster increase in protein and cholesterol concentrations after the decrease, and the antagonistic effect of atipamezole on glucose and Pi changes in autumn. Based on these results, medetomidine seems to be a good sedation agent for reindeer both in autumn and in late winter; the effects of medetomidine can be rather effectively antagonized by atipamezole.

Hematological and plasma biochemical values in captive Eld's-Brow Antlered deer (Cervus eldi thamin) in Thailand

Blood samples were collected from 20 sedated captive Eld's-Brow Antlered deer (Cervus eldi thamin), aged over 1.5 years, to define their mean hematological values (packed cell volume and hemoglobin) and mean plasma biochemical parameters. Male deer had a significantly higher plasma glucose level and aspartate aminotransferase activity than female deer.

Effects of winter on the papillar morphology of the rumen in reindeer calves

To study papillar morphology as a nutritional indicator, samples were taken from five areas of the rumen of reindeer calves (Rangifer tarandus tarandus L.) in late April 1986 (group 1, n = 6); early May 1987 (group 2, n = 6); December 1986 (group 3, n = 9); and November 1987 (group 4, n = 6). The reindeer in groups 3 and 4 were allowed to graze freely under natural conditions, mainly feeding on lichens, while those in groups 1 and 2 were kept in pens and fed with lichens. The reindeer had shorter papillae at all five points in the rumen in spring, and the mean and areal papillar volumes and the papillar surface area in the caudal blind sacs were smaller than in the animals studied in early winter. The papillae were shorter in the caudal blind sacs than in the other parts of the rumen. The highest number of papillae was usually found in the atrium or the caudal blind sacs, whereas the mean papillar volume and papillar surface area were greater in the dorsal and ventral walls. Even relatively low amounts of lichens, which are rich in easily soluble carbohydrates, seem to be sufficient to produce volatile fatty acids for the papillae in order to avoid their regression to any great extent. The even, dense distribution of ruminal papillae in the reindeer resembles the pattern found in other ruminants, which are classified as concentrate selectors.

Blood chemistry of reindeer calves (Rangifer tarandus) during the winter season

1. Blood characteristics of reindeer calves fed on lichens were studied during the winter. 2. The serum total protein, albumin and globulin concentrations decreased during the winter, obviously partly due to protein deficiency in the diet. 3. High urea levels in autumn and midwinter were possibly reflections of increased stress and/or protein catabolism. 4. Marked lipolysis occurred in late winter, and thus increases were observed in fatty acids, glycerol, triglycerides and acetoacetate concentrations. 5. Serum sorbitol dehydrogenase (SDH) activity increased towards the spring, most probably reflecting changes in the liver. 6. A decrease in serum alkaline phosphatase (AP) activity occurred in midwinter due to cessation of growth. 7. It can be concluded that all the animals were at least in moderate condition throughout the winter and the physiological responses to a negative energy balanced reflected good adaptation.