Diets of freely grazing and captive reindeer during summer and winter

The chemical composition and nutritive value of different forage plants and commercial feeds of reindeer were studied by standard methods in the Finnish reindeer herding area during 1980-86. The nutritive values, particularly the protein and mineral contents, of ground lichens (Cladina spp.) and arboreal lichens (Alectoria spp.) were very low compared to forest wiregrass (Deschampsia flexuosa), summer forage plants and commercial feeds. The crude protein and mineral content of reindeer summer food was very high. The energy content of lichens and commercial feeds was high and they are an important source of energy for reindeer in winter.


Introduction
Under natural conditions the diet of the semidomesticated reindeer (Rangifer tarandus tarandus L.J is comprised of about 250 different plants, but an additional 200 may be acceptable.A total of 106 species have been listed as the most important, including 13 lichens, 36 grasses, 29 herbs, 14 woody species, 8 mushrooms, 5 shrubs and 1 horsetail (Skuncke 1958).In winter, the basic types of fodder are lichens and some wintergreen plants.Li-Rangifer,9 (1), 1989 chens are a food specific to the reindeer, and in many arctic areas lichens constitute nearly 2/3 of the entire vegetable mass consumed by the reindeer during the year.Reindeer prefer fruticose lichens of the genus Cladina.The most important wintergreen plants are forest wiregrass (Deschampsia flexuosa), cottongrass (Eriophorum spp.), horsetails (Equisetum spp.) and sedges (Carex spp.).Arboreal lichens (Alectoria and Bryoria sp.) are important in the central and southern parts of the reindeer herding area in Finland.Reindeer eat mushrooms towards the end of summer, the most important being Boletus sp.
The snow-covered period is nutritionally the most critical part of the year, and during recent winters many reindeer in Finland have been given supplementary rations of dry hay, grains, molasses and commercial feeds.The objective of this study was to compare the chemical composition and nutritive values of the most important forage plants and commercial feeds of the reindeer.

Material and methods
The forage plants of reindeer were collected during 1980-86 from different sampling areas in the reindeer herding area in Finland.The sampling was done during June and July.The chemical composition of different important forage plants were determined by standard methods (AOAC 1980).The feed values (feed units, energy values, digestible crude protein, digestible organic matter and digestible energy values) were calculated according to Salo et al. (1982).
Forage samples were collected from several different plants of each species.Grasses and forbs were cut at ground level.Only current annual growth was collected from the shrubs and live part from lichens.

Results
The dry matter (DM) (36-49 %), crude protein and crude fat contents of Cladina lichens was very low.Slightly higher values, especially dry matter (84-89 %) and crude protein, were measured in arboreal lichens (Alectoria spp.) growing on pines and birches (Table 1).Low crude fibre contents were measured in Cetraria nivalis and in Alectoria lichens.Sugar content was higher in ground than in arboreal lichens.The lowest sugar content was measured in Cetraria nivalis.N-free extract content of Cladina lichens was rather high.Slightly higher values were measured in Alectoria lichens (Table 1).The ash, Ca, Mg, P, Na, K, Cu and Zn contents in Cladina lichens were very low compared to other food plants (Tables 2 and 4).Similar low values were measured in arboreal lichens.Fe and Mn contents were higher in Cladina lichens than in Alectoria lichens.

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The ash content of the different forage plants was very high during summer and varied between 2.0-18.3% in DM.The mineral and trace element values also were high, Ca ranging from 1.1-18.0g/kg DM, P from 0.6¬ 4.1 g/kg DM, Mg from 0.5-6.9g/kg DM, K from 3.4-29.6g/kg DM, Na from 0.02-7.45g/kg DM, Cu from 0.7-13.1 mg/kg DM, Fe from 41-1852 mg/kg DM, Zn from 8-425 mg/kg DM and Mn from 72-2423 mg/kg DM (Table 4).
The crude protein content of dry leaves, harvested for winter feed, of Betula and Salix varied between 14.2-18.4% DM (Table 3).The digestible crude protein content was high, ranging from 112-175 g/feed unit.The crude fibre content varied between 13.7-18.7 % DM, crude fat between 5.4-6 % DM, Nfree extract between 51.4-61.4% DM and sugar between 7.3-12.4% DM.The feed unit values of dried leaves ranged from 2.45-2.97kg DM/feed unit.The ash (range from 4.7¬ 5.6 % DM), mineral and trace element contents of dry Betula and Salix leaves were very high (Table 4).
The feed unit values of commercial fodders vary between 1.3-1.76kg/feed unit and between 1.2-1.53kg DM/feed unit.The digestible organic matter content varies between 523-643 g/kg DM and the digestible crude protein content between 97-187 g/feed unit.The crude energy value of commercial fodders is on average 18 MJ/kg DM.The mineral and trace element values of commercial fodders are high compared to both lichens and green plants except for Mn which is higher in the latter (Tables 2, 4 and 7

Mushrooms are a valuable nutritive and vitamin-rich fodder for reindeer during autumn and sometimes early winter. The crude protein content is on average 23 % in DM.
Mushrooms consist mainly of water (90 to 93 %), but the dry matter is rich in proteins and enzymes according to Kreula et al. (1976).Their ash contains 3.1 % K and 0.47 % P (Isotalo 1971, Tables 12 and 13).Mushrooms contain much sugar, fat, and numerous vitamins, especially A p B" B2, C and D. The cellular tissue of mushrooms is rather indigestible, and its presence reduces the nutrient value of this fodder (see Karaev 1961).According to Staaland and Saebo (1987) the fibre content of mushrooms is, however, very low and it is assumed that easily digestible mushrooms could Rangi£er,9 (1), 1989 DM/feed unit.The digestible organic matter in lichens was 691 g/kg DM and the crude energy content on average 18.8 MJ/kg DM.Slightly lower feed unit values were measured in Alectoria lichens growing on pines and birches (1.21 and 1.13 kg/feed unit, and 1.01 and 1.01 kg DM/feed unit, respectively).The digestible crude protein (DCP) content was virtually zero in Cladina lichens.Slightly higher values were measured in Alectoria lichens.The crude energy content in Alectoria lichens growing on pines and birches were on average 19.2 and 20.1 measured in E. angustifolium and M. trifoliata.The content of N-free extract varied between different plants (range 43.6-71% DM).The sugar content varied between 0.1-24.4% DM, and the highest values were measured in D. flexuosa, S. lapponum, B. nana, Carex spp.and Equisetum spp.
).The feed components and chemical composition of the concentrates used for the feeding of the reindeer during summer in feed components (% fresh weight) of the commercial reindeer fodders used in Finland during winter (Poroelo and Poroelo S produced by Suomen Rehu Oy, Poro-Ennatys by Rehumestari Oy, Poro-Rehu and Valtti by Hankkija Oy, Poro-Evas by Lannen Tehtaat Oy and Poron-Herkku and Poron-Herkku 2 (year 1986) by Raision Tehtaat Oy).
diet of freely grazing reindeer varies greatly through the seasons.Energy-rich lichens usually form the major component of reindeer' s diet during winter and early spring.Lichens, however, are poor in protein and mi-nerals, so that other foods, such as wintergreen grass (e.g.D. flexuosa), is essential to maintaining the condition of reindeer during winter.Under very good lichen grazing conditions the reindeer gain fat, which means that there is surplus energy for its production.At the same time the lack of protein in the diet causes a breakdown of muscle (e.g.Nieminen 1980).Protein and minerals must therefore be stored by the reindeer during summer and autumn for the needs of the winter.During summer reindeer feed highly selectively.The chemical data presented here may therefore underestimate the quality of their summer diet.
consumed without being detected in samples of rumen content.About two thirds of the reindeer in Finland get their food on natural pastures during winter.The remainder seek out arboreal lichens in the cutting areas in the forests or are fed in corrals or in the field.Forests which are rich in arboreal lichens constitute mostly the restricting factor of carrying capacity in these areas, when ground lichens are reported to be a limiting factor in northern areas (see e.g.Nieminen 1980).Consequently many reindeer have been supplemented with dry hay, dry birch and willow twigs and leaves, grains, dry molasses pulp and commercial fodders during recent winters.During the snow-free period (about 160 days) the reindeer has usually small problems in fulfilling its nutritional requirements.However, it is suggested that the high level of K in reindeer summer forage increases Na excretion and drains the body reserves of this mineral.According to Staaland and Saebo (1987) the body reserves of Na are apparently rebuilt through autumn and winter.The crude protein content of commercial fodders used for supplementing reindeer varies between 8-16.7 % DM.The mean of crude protein content in the most of common fodders is 10.5 % in DM.This is lower than the crude protein content in fodders given to reindeer and other cervids in the zoos and game farms, but equal with that of the reindeer commercial fodders used in Sweden (8 are also highly digested because reindeer/caribou both are able to increase their rumen retention time and to ferment lichens.That high digestibility, combined with a high carbohydrate content, makes lichens extremely high in digestible energy compared with other natural winter foods (seeRussell and Martell 1984).Boertje (1981) concluded that energy was probably the limiting factor for reindeer in winter.Rangifer, 9 (1) 1989