Utilization of nitrogen- and mineral-rich vascular forage plants by reindeer in winter

Abstract

The marginal winter pastures of reindeer and caribou (Rangifer tarandus) in Arctic and sub-Arctic areas are assumed to be nitrogen-and mineral-poor. Reindeer eat a mixed diet consisting of nitrogendeficient lichens and a wide variety of vascular plants in winter. Some reindeer populations manage to maintain carcass mass outside the growing season and very little is known about the ability of reindeer to utilize vascular plants in this season. The chemical composition and in vitro digestibility of 17 species of vascular forage plants and one species of moss collected mid-winter from beneath the snow at an inland winter pasture in northern Norway were determined. Wintergreen parts of graminoids had a high content of crude protein (0n072-0n108 g\kg dry matter (DM)) and watersoluble carbohydrates (0n098-0n167 g\kg DM) and were highly digestible (50-65 % IVDMD) compared with the withered parts of the plants (27-53 % IVDMD). The digestibility of both shrubs and graminoids was inversely related to content of cellulose and lignin, but positively correlated with increasing contents of water-soluble carbohydrates. Shrubs were relatively calcium-rich (3n6-6n1 g\kg DM) while wintergreen graminoids contained up to 10n0 g\kg DM of potassium, 1n5 g\kg DM magnesium and 2n1 g\kg DM phosphorus. The present study demonstrates that the wintergreen parts of several species of vascular plants are nutritious, containing high levels of nitrogen and minerals, and that they are highly digestible to reindeer in winter. Vascular plants may, therefore, be more important to reindeer and caribou in winter than previously realized.

Above ground biomass changes in the mountain birch forests and mountain heaths of Finnmarksvidda, northern Norway, in the period 1957–2006

“…) and provide open sites (e.g., Butler, 1995) which may lead to seedling emergence (Eskelinen and Virtainen, 2005;Brå then et al, 2007). Our findings indicate that high densities of reindeer can promote the growth of mountain birch in winter grazing areas by grazing down the thick layer of the lichens, in addition to the fact that reindeer mainly feed on lichens (bottom layer) and species in the field layer (forbs and grasses) including dwarf shrubs like Vaccinium myrtillus and Empetrum hermaphroditum during winter (Storeheier et al, 2002a(Storeheier et al, , 2002bTømmervik et al, 2004).…”

Where clocks are redundant: weak circadian mechanisms in reindeer living under polar photic conditions

“…Instead, they continue to feed selectively in winter, maintaining relatively high concentrations of nutrients in their diet (e.g. Storeheier et al 2002) though at a cost of very low absolute rates of intake (<4 g DM·min −1 in calves, Storeheier et al 2003) for which they compensate by grazing at night even under the daily LD cycle of spring and autumn. The continuous pattern of feeding in reindeer may, in addition, enhance digestive efficiency by maintaining substrate supply and, hence, stabilizing the environment of microorganisms in the rumen (Leedle et al 1982; but see also Dehority and Tirabasso 2001 for a review).…”

Ecology of Uncultivated Oscillospira Species in the Rumen of Cattle, Sheep, and Reindeer as Assessed by Microscopy and Molecular Approaches

“…Rumen samples were collected from four healthy semidomesticated female adult reindeer (Rangifer tarandus tarandus) feeding on natural winter pasture dominated by lichens in northern Norway (28,29). This sample set supplied DNA for PCR-DGGE analysis.…”

“…Microscopic count data showed the highest numbers of this specific morphotype were recorded during green pasture feeding and ranged from 2.5 ϫ 10 5 to 6.8 ϫ 10 5 per ml of rumen fluid from cattle (Table 1). Direct microscopic counts of Oscillospira-like bacteria in reindeer are high (generally 10 7 but as high as 1.5 ϫ 10 8 ; Table 1) and are associated not only with a diet of fresh summer pasture but also with winter diets containing large quantities of lichens and subarctic plants, including graminoids, shrubs, and heathers (28,29). Unusually high numbers of Oscillospira were reported in the rumen of sheep on the island of North Ronaldsey, Orkney, Scotland, fed seaweed (2.5 ϫ 10 7 ) (28).…”

“…Oscillospira organisms were identified by their large size and distinct morphology (11,18). This sample set supplied DNA for PCR and PCR-DGGE analysis.Rumen samples were collected from four healthy semidomesticated female adult reindeer (Rangifer tarandus tarandus) feeding on natural winter pasture dominated by lichens in northern Norway (28,29). This sample set supplied DNA for PCR-DGGE analysis.…”