Salivary glands in Svalbard reindeer {Rangifer tarandus platyrhynchus) and in Norwegian reindeer (Rangifer tarandus tarandus)
S. D. Mathiesen12, V. B. Rædergård1, M. A.Vader1, 0. E. Haga2, H. J. Norberg3, W. Sørmo2, & N.J. C.Tyler4
1 Department of Arctic Veterinary Medicine, The Norwegian School of Veterinary Science, N-9292 Tromsø, Norway ([email protected]). 2 Department of Arctic Biology and Department of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway. 3 Department of Biology, University of Oulu, FIN-905 71 Oulu, Finland. '' Department of Biology, University of Tromsø, N-9037 Tromsø, Norway.
Abstract: The aim of this investigation was to compare the size of salivaty glands in Svalbard reindeer {Rangifer tarandus platyrhynchus) and in Norwegian reindeer (Rangifer t. tarandus) in relation to feeding strategy, season and reproductive status. The mean body mass (BM, standard deviation j) in adult non-lactating female Svalbard reindeer was 72.0, s = 4.2, kg (n = 8) in September and 46.7, s = 7.1, kg (« = 4) in April. The mean BM of adult non-lactating Norwegian reindeer was 67.5, s = 7.7, kg (» = 8) in September and 59.2, s = 9.6, kg (n = 9) in March. In non-lactating female Svalbard reindeer the mean combined mass of parotid glands was 82.7, s = 4.5, g in September and 58.8, s = 8.7, g in April (P < 0.05). In the Norwegian reindeer the mean combined mass of the parotid glands was 95.2, s = 14.4, g in Septembet and 68.1, s = 9.5, g in Match (P < 0.05). We wete not able to find any sub-species differences in the size of the salivaty glands which could be related to phenotypic difference in feeding strategy. Both sub-species had parotid glands sizes similar to that of intermediate ruminant types, ranging from 0.11-0.14% of BM. The larger absolute size of salivaty glands in summer compared to winter reflects the importance of high rates of production of saliva when the dry matter intake and microbial fermentation is high.
Key words: digestion, feeding strategy, seasonal variation.
Rangifer, 19 (1): 25-32
Introduction centrate selectots (CS), like roe deer (Capreolus capre- The relative size of the salivary glands in different olus), in which the parotid glands comprise between species of ruminants is closely associated with their 0.18 and 0.22% of BM (Kay, I960; 1989; feeding strategy and reflects a functional relation• Hofmann, 1973; 1989)- In addition to the impor• ship between the mass of the glands and the compo• tance for swallowing and rumination, ruminants sition of the diet (Kay et al, 1980; Hofmann, 1985; produce saliva to supply alkali to buffer the ruminai 1989; Kay, 1987; 1989). Thus, the glands tend to microbial production of volatile fatty acids (VFA) be relatively small in grazers (GR), like sheep (Ovis and lactate and maintain the pH of the rumen close aries), in which the parotid glands comprise only to 6.5. To achieve this, the four paired salivary 0.07% of body mass (BM), and much larger in con- glands (parotid, mandibular, sublingual and buccal
RangiSer, 19 (1), 1999 25 glands) can produce as much as 16 litres of fluid per precipitation is 250 mm (climate data from the day in domestic sheep (Kay, 1958; I960). The Norwegian Meteorological Office). Snow lies for up mandibular glands secrete mucus and hypotonic to ten months annually, but the climate is unstable buffer (Kay, I960; 1966). A secondary role of the with temperatures occasionally rising above freez• parotid glands in concentrate selectors and interme• ing even in winter, resulting in alternating periods diate feeders is to secrete tannin-binding proline of thawing and freezing which can produce crusts of rich protein in the saliva which makes these animals ice in the snow through which the reindeer have more tolerant to tannin in the diet compared to difficulty in digging to reach the plants beneath. grazers like sheep (Robbins et al., 1991)- Concen• Consequently, in most yeats by late winter (March trate selectots and some intermediate feeding types and April) the animals are restricted to feeding on exhibit incteased salivary secretion when offered exposed, windblown ridges where the aerial biomass tanniniferous feed, reflecting hypertrophy of the of forage is low (Tyler, 1987a; b). glands (Butler, 1989; van Soest, 1994). Several Norwegian reindeer were taken from a semi- anatomical characteristics of the digestive system domesticated herd in Finnmark, northern Norway indicate that both Svalbard and Norwegian reindeer (69°N). This herd, managed by Sami herders, are intermediate ruminant feeding types (Aagnes & migrates about 200 km between inland winter pas• Mathiesen, 1996; S0rmo et al, 1999) although the tures and coastal summer pastures (Fig. 1). The high arctic Svalbard reindeer bears some similarity animals feed on natural mountain pastute all year to concentrate selectors, like high ruminal VFA pro• round, eating a wide variety of vascular plants, duction rates, short intestines and large distal fer• including sedges and grasses, e.g. Carex spp. and mentation chambers (White & Staaland, 1983; Poa spp, dwarf shrubs, e.g. Loiseleuria procumbens and Staaland & White, 1991; S0rmo et al., 1997; 1999; Empetrum spp., birch and willows, Betula nana and Mathiesen et al., 1999a). We therefore predicted Salix spp., and also including a significant amount that Svalbard reindeer would have larger salivary of lichens in their diet in wintet, e.g. Cladina spp., glands than Norwegian reindeer at least in summer. Cetraria nivalis and Stereocaulon spp. (Mathiesen et According to Hofmann (1989) and Kay (1987; al, 1999b). At the coast in summer, the weather is 1989) it is tempting to assume that parotid weight cool and wet, mean tempetature for July being 10 reflects daily saliva volume secreted and is influ• °C, and precipitation exceeds 1000 mm annually. enced by food intake. We therefore predicted that Inland winter range is cold and dry (mean tempera• the mass of these glands in reindeer would be influ• ture for February is -14 °C, while yearly precipita• enced by the animals' reproductive status. Finally tion is less than 400 mm (climate data from the we predicted that the size of the salivary glands Norwegian Meteorological Office). The cycles of would fluctuate seasonally in both sub-species, thawing and re-freezing which create crusts of ice reflecting changes in food intake and in the avail• occur here much less frequently than at the coast. ability and quality of forage plants. Animals Adult female Svalbard reindeer (age > 2 years old Material and methods based on the pattern of eruption of molariform Study areas teeth), were selected at random from groups grazing Svalbard reindeer were collected in Sassendalen, a undisturbed, and killed by a single shot in the chest valley in Nordenskiold Land (NL, 78°N), Svalbard in October 1994 (» = 11), in April 1995 (» = 4) and (Fig. 1). Approximately 4000 reindeer live in NL in September 1996 (n = 13). Known age adult (Tyler, 1987a) feeding on tundra vegetation domi• female Norwegian reindeer were killed in nated by different species of grasses, sedges, herbs September 1995 (« = 8), November 1995 (» = 7), and dwarf woody plants belonging to the genera February 1996 (« = 6) and in March 1996 (n = 9). Poa, Deschampsia, Alopecurus, Luzula, Empetrum, SalixTh e animals were selected by hand after the entire and Dryas. Mosses make up a significant part of the herd had been gathered in a paddock, stunned in plants found in the rumen of these animals in win• the traditional Sami manner, which involves the ter (S0rmo et al., 1999). This part of Svalbard is cold rapid insertion of a fine blade through the foramen and dry: the mean winter temperature at magnum and into the ctanium, and killed by bleed• Longyearbyen is -14 °C, while mean temperature in ing by cutting the major vessels close to the heart. July, the warmest month, is about 6 °C. The annual Post mortem examination of all reindeer was carried 26 Rangifer, 19 (D, 1999 dressed carcass is the whole animal less the entite gastrointestinal tract and its contents, the head, the pelt, the lowet legs, the uterus and its contents, the udder and all the visceral organs including the kid• neys). The head was removed by cutting between the cervical vertebrae approximately 20 cm from the cranium, to secute the salivaty glands; the feet were removed by cutting between the distal carpus and the metacarpus and between the distal tarsus and the metatarsus. The weight of the short pieces SVALBARD of the neck was added to the slaughtet weight aftet dissection of salivary glands. The Glandula parotis and the Gl. mandibularis were carefully dissected out on tight and left side (Fig. 2) and each pait of glands was weighed to 0.01 g on an electronic balance. The paired glands were then dried to constant weight at 115 °C, cooled to room temperature in a dessicator and re-weighed to determine dry mass (DM). The left femur was dis• sected out and its gteatest length was measured to 1 \ mm in a bone box. Indices of the mass of Gl. parotis • _ and Gl. mandibularis were calculated as [(g DM/f3) x 106] where f3 is the cube of the greatest length of the femur (cm) (Tyler, 1987a).
\. Statistical analyses Results are given as mean and standard devia• tion (s) of the mean. Significance was tested by Students t-test. The null hypothesis was rejected at P < 0.05. Fig. 1. The Svalbard reindeer were collected at Nordenskiold Land (NL) in September, October and April. The Norwegian rein• Results deer were collected at Magerøya (MA) in September and at Soussjavre (SJ) in November, January and March. Body mass There was no significant difference in BM between non-lactating adult female out in field laboratoties»starting within 45 minutes Svalbard reindeer and Norwegian reindeer in of death. September. In late winter, however, BM was signifi• The total BM of Svalbard reindeer, less blood lost cantly larger in Norwegian reindeer compared to from the wound, was recorded to 1 kg using a Salter the Svalbatd reindeer (P < 0.05, Table 1). Non-lac• mechanical scale (1-100 kg). The live BM of the tating Svalbard reindeer (mean BM 72.0 kg) tended Norwegian reindeer was measured to 1 kg in a to be heavier in autumn than lactating animals weighing ctate equipped with an electronic digital (mean BM 66.6 kg) though the diffetence was not scale. Once dead, the gastrointestinal tract was significant (Table 1). Both these groups, howevet, removed from each animal and the reticulo-rumen were heavier than Svalbard reindeer killed in late (RR) was weighed full to 1 g on an electronic bal• winter (April, mean BM 46.4 kg, P < 0.05, Table ance after stripping off both the mesentery and the 1). Norwegian reindeer, likewise, tended to be heav• adhering adipose tissue. The wet mass of ingesta in ier in September (mean BM 67.5 kg) than in March the RR was calculated by subtraction after empty• (mean BM 59-2 kg), but the difference was not sig• ing the RR and re-weighing it, less contents, to 1 g. nificant (Table 1). Hot carcass mass (CM) was measured by weighing There was no significant difference in CM the dressed carcass to 0.1 kg on a 150 kg steel yard between Svalbard reindeer and Norwegian reindeer immediately after the animal was skinned. (The in September. In late winter, however, CM in the Rangifer, 19 (1), 1999 27 ^ ^ CO rN Norwegian reindeer was signifi• NO o oo -—< o o ! <—i o o cantly greater compared to ON o ON d d d d d d Svalbard reindeer (P < 0.05, 2; rN q ,_, 00 XT m /"l N ON co oo ITN oo d d m o Table 1). CM of non-lactating NO d d d d d CN rN m Svalbatd reindeer (mean 35.8 kg) ^ ^
,—, ^—v ^—* ,—s ,—s i—i was significantly greater in NO o om r-- o oCN cq NO cn d .—( d d d oo d d d autumn than in lactating animals W ft O oo ON ON CM NO m (mean 29.4 kg, P < 0.05) and the o ON o ITN xf d CN d o CM of both groups was signifi• NO CN 00 rN d d m d d 3 cantly greatet compared to Sval• ,—. ,—s ,—s ,—v CN ,—, ,—i CN ,—v ..— \—i MN bard reindeer collected in late rN CM ON q o CN <—i o o ON •-< CNJ d d d d 00 d d d winter (mean 19-9 kg, P < 0.05, o ly-N \r\ o rN oo m ITN m Table 1). In the Norwegian rein• r-^ NO d d i—i rN d O NO -—i CN 00 d d d o deer, by conttast, there was no significant diffetence in CM CN ^ CN between animals collected in ON m NO r- o o oq q q H m CN d September and in March (means m d d d w UN X CN in (N NT (N o NO r^- NO 29.8 and 28.5 kg respectively, CO h OsO _; ^ "N oo d o \D (N H rN d Table 1).
rN NO rN rri Reticulo-rumen content <—i t-^ NO rN © o m o o K oi ^ d o © NO Mean mass (wet weight) content pi ON «N ON rO O of RR in Svalbatd teindeer was ^ NO ^ ^2 NO ON ON 00 '—' m ^° d • • 8.9 kg (12.3% of BM), compared rN d d CN o o to 10.9 kg (16.1% of BM) in •—i rN Norwegian reindeer in H (N IN h •?r rn o o NO o o ^ rn m 6 NO odd vn O September but the diffetence was ITN rN q NO ITN rN NO 1/-N o not significant. In late winter, the rN ON r_; d rN rN ON d o mean mass (wet weight) of the H NO CN CN d d rN d o 1 U - contents of RR was 9-3 kg O (20.0% of BM) in Svalbard rein• Q XT ON o o o o d d m d on d d d deer compared to 8.4 kg (14.2% < l/N d d m oo ON r-- 00 oo of BM) in the Notwegian rein• -—i oo NO ON rN rN o oo d o o PQ NO rN NO d d rN d d deer (Table 1). The mass (wet weight) of the contents of the RR r ^ ^ ^ ^ oo ,—, ,—^ , y , y XT CN CN ^—^ ,—, was not significantly greatet in m 00 m rN CN O o <—' o o ^' i—i d d d d CO d d d lactating Svalbard reindeer in
NO rN NO IVN XT CN m ON NO ^r September (mean 11.2 kg) com• NO ON ,_<' xf CN m CN d o pared to non-lactating Svalbatd NO rN CN ON d d d d H reindeer (mean 8.9 kg, Table 1). w ^ ^ ^
OO ,—, ,—^ ^—^ ,—s •—i rN ,—^ ,—^ —i There was no significant differ• CN 00 '—' r q oq ON 00 rN m oq NO weight) of RR contents between rsi 00 CN CN xf d q non-lactating Svalbard reindeer m CN oo d d m d o collected in September and in April (mean 9.3 kg, Table 1). In a Norwegian reindeer the mean u mass (wet weight) of rumen con• o d tents decreased from 10.9 kg in X September to 8.4 kg in March but the difference was not signi• ^ 2 cq U pd, pc r< CO G .s ^ ^ G .s ^ ^ ficant (Table 1). 28 Rangifer, 19 (1), 1999 T±1 r-w -T-IF-F-- ntfm rod rft pM-t ^hmk ijj m arhr-a* to brrr nou- ••] m fmUr vurfe Ihf h t.OSŒNThAtl- LSllhMiniATI FEEEJrlU GRA/IA SELECTOR Rue "^ilJfryftl rxindrrr '•.'i.riT Vb UH •HPV 47 li yj u u 1 » 2_Z 1 LJ M 1J ai ! i T Ka'I I i "'N " J.J him mw ka (hr Narwrjtitfi EtiErktt(Hfe I : Thf pmid fiicnb utor drep* r nnbcddrd im 4B rn rwMHÜailMr foui ind *m wijraped imivJ bf rw --I :l.r. EAT TV «hjrjulif füuk «nr fr.' /u bergen IriWHfi «nd non-lniHcui S^pJn«d itiJï^FT m r^ber Vcitcmbrr ar in CMukrr i- 'i Li il wrrr hnJwr iJi Srpti-mtwr ralW P«ml TE? OtEuber ni t-rih JRHipf CTlblr Lj Mn|i cw rf fj/ ymzj rrurim PifiM. rr™e*w_ WÉI T-jf- nhciH^p rh « Ofllj Unar w pmwj qph-HKtUiJI Srdbrrd m inker m brrri V|HiM^J •id UfttrH. IA SnJtvj fnnckrt Lu_b the ftnn •tim 9 i ï>0ïj urJ ihr I^M irkkx fj* r om] ai Jannik *rrr ii^nibi un ly jtmur in ârpfrmkr nrml tr> A/nl imui mru J :n^jr: inEk'x I ^. x - L TihLr H Ltknktt. II [tc N'unrrrLm rfftr dnf
pL.I. UffAiVichr prriTf in Ntifw/bLn TTtchJnr • -r i raml uWlnnJ mr^m ifi Srpiroibrr fj* < Dffl) brt Ob WEH|E£B lUifi r TU IrrrfrJ . • U*r • htt iTlbfr Jr TbCft WÉii hfr MjinirKLJll Jarfrtrfl^r m Pif. 7. iLwwl llfeC puHirinn nf rfx rij(hi liJrHary riv mw (WET vr^flhcï ol CrV. MWrifJjffTj hrrwrtfi jjluidj (fW nuiJ^jjTTj ud fpV. pjMf. in £viLhird LM rur i n j| und nnn-Li rj 111: n Snibud rvindcfr n rrLOilon LU tptrfflbl. ! '- ilirtdi nn rhlhrf V • r !*r nr in ( h MUTT ilttkJUKh in hvh ir nru -ciKp^rht J.Ü m Z4 tiu «ur chui LEM rCruuEii ijljrkJi Wtfc Ltfjnrf IR Sfnmitûrt -LurnfMrvd loOriobf Q.QVTibk Li L^DMHU imndibulw gUn* in SwJbånJ iHhkcr nd L9 «¬ r, CII. IW mass of Gl. mandibularis relative to CM was not sig• degree of rumen papulation was similar to that nificantly different between lactating and non-lac - observed in concentrate selectors and decreased tating Svalbard reindeer. from summer to winter (Josefsen et al., 1996). The Both the mean mass (P < 0.05) and the DM rumen papillae in Svalbard reindeer remain to be index (P < 0.05) of glands were significantly greater investigated. Vety rapid absorption of VFAs across in Septembet (mean mass 34.5 g, mean index 0.8, n the tuminal epithelium in Svalbard reindeer might = 8) compared to April (mean mass 26.3 g, mean explain why the salivary glands of this sub-species index 0.6, n = 4). In the Norwegian reindeer both are no larger than in Norwegian reindeer despite the mass and the mean DM index of the mandibulat the vety high rate of production of VFAs in summer glands were significantly heavier in September (White & Staaland, 1983). The use of salivary (mean mass 480 g, mean index 0.6, n = 8) compared glands in the classification of feeding strategies in to March (mean mass 30.3 g, mean index 0.3, » = 9) ruminants has therefore to be supplemented with (P < 0.05). other data. Mean mass of salivary glands tended to be latger in lactating females than in non-lactating females Discussion. (Table. 1). According to Hofmann (1989) and Kay Our hypothesis that Svalbard reindeer might have (1958; I960; 1989) it is tempting to assume that larger salivary glands than Norwegian reindeer, the weight of the parotid glands in domestic sheep reflecting a more concentrate selector like feeding reflects the rate of secretion of saliva and food strategy in the former, was not supported. We found intake. However, the rate of secretion has not been no difference in either the absolute or the relative measured in wild ruminants. Presumably, however, mass of salivaty glands between sub-species regard• the latger salivary glands of lactating Svalbard rein• less of season (Table 1). The relative masses of the deer reflect higher food intake. Likewise, the mean parotid glands and the mandibular glands of the mass of the RR contents tended to be greater in lac• two sub-species ranged between 0.09-0.14% and tating Svalbard reindeer shot at the same time while 0.04-0.07% of BM, respectively, indicating that foraging on the same vegetation, indicating greater both are intermediate feeding type ruminants food intake in these animals. according to Hofmann's (1985) classification (Tables The fact that the mass of both the parotid and the 1 and 2). The classification of reindeer as an inter• mandibulat glands was significantly greater in sum• mediate ruminant feeding type was also supported mer and autumn than in late winter in both sub• by data on the digestive anatomy and functions in species lends further weight to our suggestion that the two sub-species investigated, including omasal the mass of the salivary glands is related to the level structures and gastro- intestinal fill, although the of food intake. Svalbard reindeer and Norwegian Svalbard reindeer have several digestive adaptations reindeer face a pronounced seasonal variation in found in ruminants of the concentrate selector type appetite (Larsen et al., 1985) and in seasonal (Aagnes & Mathiesen, 1996; S0rmo et al, 1999; changes in the availability of forage which influence Mathiesen et al, 1999b). both BM and body composition in these animals The mass of the salivary glands and their secre• (Reimers et al, 1982; Tyler, 1987a, b). We believe tion of buffer is not necessarily correlated with the these factors also influence on the size and function mass or volume of the rumen, but rather with the of the salivary glands in reindeer. quality of the diet eaten. In a cross-species compari• The changes observed in the mass of the salivary son Kay (1987) predicted that the relative mass of glands may also reflect changes in the chemical the parotid gland might increase with the composition in plants eaten in summer and winter. digestibility of the diet that is naturally consumed. The quality changes of fotage plants eaten are re• Even so, the high tuminal need for buffer is not flected in the chemical composition of RR contents always a sufficient explanation of large salivary in these animals. The crude protein concentration in glands in concenttate selectots and intermediate the RR content was high in summer (34.4% DM), feedets. These ruminant feeding types have a much but very low in winter (15.1% DM) in Svalbard more papillated rumen absorptive surface and, reindeer. Corresponding values for Norwegian rein• hence, very efficient absorption of VFAs across the deer are 28.0% in summer and 23% in winter rumen epithelium compared to grazers (Hofmann & (Staaland et al., 1983, S0rmo et al, 1999, Mathiesen Schnott, 1982). In Notwegian teindeer calves the et al, 1999b). In moose, seasonal changes in the 30 Rangifer, 19 (1), 1999 mass of salivary glands also reflect reduced forage and fed baled timothy silage in summer and winter. - quality and intake in winter. The parotid glands of Rangifer \(r. 31-39. moose atrophied from as much as 0.18% of BM in Butler, L. G. 1989- Effects of condensed tannin on ani• summer to 0.13% of BM in winter (Hofmann & mal nutrition. - In: R. W. Hemingway & J. J. Karchesy (eds.). The Chemistry and Significance of Nygren, 1992). Further, specific chemical con• Condensed Tannins. Plenum press, New York, pp. stituents in the diet of reindeer (Mathiesen et al., 2401-2412. 1998b; S0rmo et al., 1999), like tannins, could also Chowdhury, S. A. 1992. Protein and fat metobolism during influence the mass of the salivary glands (Butler, undernutrition. PhD thesis, University of Aberdeen. 1989) but the tannin concentration in arctic plants Hofmann, R. R. 1973. The ruminant stomach: Stomach eaten by reindeer remains to be investigated. structure and feeding habits of east African game ruminants. Likewise, the forage fibre content is mainly respon• East. Afr. Lit. Bureau. Nairobi, Kenya. 354 pp. sible for reflex stimulation of the parotids from sen• Hofmann, R. R. 1985. Digestive physiology of the deer sitive ateas of the mouth, oesophagus and reticulo- - their morphophysiological specialization and adap• rumen (Kay, 1989). According to Wilson (1963) tation. Biology of deer production. - The Royal Society the parotid glands in young lambs increased in of New Zealand, Bulletin 22: 393-407. response to the toughage content of theif diet and Hofmann, R. R. 1989. Evolutionary steps of ecophysio- not to the fermentability of the fotage eaten. logical adaptation and diversification of ruminants: a Recently, Chowdhury (1992) suggested a consider• comparative view of their digestive system. - Oecologia 78: 443-457. able regression of parotid glands of sheep aftet 7 Hofmann, R. R. & Nygren, K. 1992. Morphophysio• weeks maintained on liquid gastric infusion with• logical specialization and adaptation of moose diges• out the mechanical stimulus of solid food consump• tive system. - Alces (suppl. 1): 91-100. tion. In Svalbard reindeer ruminal lignin content Hofmann, R. R. & Schnorr, B. 1982. Die functionelle incteased from 18.2% organic dry mattet (ODM) to Morphologic des Widerkauer-Magens. Stuttgart. Ferdi• 25.5% in winter, while the ruminal lignin content nand Enke Verlag. 71 pp. was about 15.0% ODM in Norwegian reindeer in Josefsen, T. D., Aagnes, T. H. & Mathiesen, S. D. both summer and winter (S0rmo et al. 1999; 1996. Influence of diet on the morphology of ruminal Mathiesen et al., 1999b). It is therefore unlikely papillae in reindeer calves (Rangifer tarandus tarandus that the plant fibre content but rather the level of L.) - Rangifer 16: 119-128. food intake and forage digestibility are the reason Kay , R. N. B. 1958. Continuous and reflex secretion by for the seasonal changes in size of the salivary glands the parotid gland in ruminants - J. Physiol. 144: in the two subspecies observed. 463-475. Kay, R. N. B. I960. The rate of flow and composition of Seasonally, therefore, the salivary glands in rein• various salivary secretions in sheep and calves. - J. deer, vary in size, influenced by the quality and Physiol. 150: 51 5-537. quantity of forage eaten. The large absolute size of Kay, R. N. B. 1966. The influence of saliva on digestion salivaty glands in summer compared to winter in tuminants. - World Review of Nutrition and Dietetics reflects their importance particularly in summer 6: 292-325. when rumen microbial fermentation is high. Kay, R. N. B. 1987. Weights of salivary glands in some ruminant animals. - J. Zoo/. London 211: 431-436. Kay, R. N. B. 1989. Adaptation of the ruminant diges• Acknowledgments tive tract to diet.-Acta Vet. Scand.Suppl. 86: 196-203. This work was supported by the Reindeer Husbandry Kay, R. N , Engelhardt, W. V. & White, R. G. 1980. Development Fund under the auspices of Norwegian The digestive physiology in wild ruminants. - In: Ministry of Agriculture and by the Norwegian Research Ruckebush, Y. & Thivend, P. (eds.). Digestive physiolo• Council. We thank the teindeer herder Mathis A. Sara, gy and metabolism in ruminants. 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Manuscript received 28 September, 1998 accepted 10 June, 1999
32 Rangifer, 19 (1), 1999