Bacterial fermentation of lichen and ruminal responses to starvation in Norwegian reindeer "

Tove Hilde Aagnes Utsi is from Gildeskål municipality in Nordland county, Norway and was educated at the Department of Arctic Biology, Institute of Medical Biology, University of Tromsø. She was Cand. Scient, in 1990 with a thesis entitled "Bacterial fermentation of lichen and ruminal responses to starvation in Norwegian reindeer". Aagnes Utsi continued with a scholarship for the period 1991-1994 studying ruminal responses to a natural winter pasture in reindeer and grass silage as emergency food for reindeer. The study has been in close collaboration with the Norwegian Crop Research Institute, Holt Research Centre, Tromsø and Norwegian College of Veterinary Medicine, Department of Arctic Veterinary Medicine, Tromsø. She has from 1995 had a position at the Norwegian Reindeer Husbandry Administration in Alta.

In addition, it should preferentially meet the animals maintenance energy requirements.To find such food, basic knowledge of the digestive processes in reindeer were needed and made basis for this study.
To investigate if reindeer had special adaptation to maintain the rumen function when exposed to acute starvation, rumen fluid volume and fluid turnover time were measured in reindeer fed pure lichen and after four days of starvation, by using a liquid-phase chromium-EDTA marker (paper I).In lichen fed reindeer rumen fluid volume and turnover rime varied considerably between animals (volume range 3.8-10.81; turnover range 22.5-69-0 h), but were fairly constant in individual animals.These values did not change significantly in response to starvation, mainly due to a conspicuously increased snow intake.This fact naturally reduced reticulo-rumen dry matter and microbial population, which in turn will reduce the ability of the animal to digest plant material after starvation.
In free-living reindeer from northern Norway, eating a mixed winter diet dominated by lichens, the rumen fermentation, bacterial population density and composition were studied, and compared with reindeer fed pure lichen and subsequently starved for four days (paper II).Bacterial population densities in the rumen fluid and associated to the plant particles were recorded, using the dilution method and habitat stimulating growth medium, both in lichen fed and free-living reindeer ranging between 15.0-500.0x 10 s bacteria per ml rumen fluid and per gram rumen solids.The bacterial population density associated to the plant particles was significantly higher in the free-living reindeer than in the lichen fed.The bacterial composition in the free-living reindeer seems to be adapted to a fibre digestion, which could not be found in the lichen fed animals.Total ruminal volatile fatty acid concentrations ranged between 57.4-72.1 mM in the lichen fed reindeer compared to 70.4-82.6mM in the free-living reindeer.Srarvarion for 4 days reduced the rumen bacterial population densities both in the tumen fluid and associated to the plant particles more rhan 90%, the bacterial composition changed, ruminal pH increased and ruminal volatile fatty acid concentration decreased considerably.The study indicates that intake of a natural mixed winrer diet improve the growth condition of the rumen bacteria and microbial digesrion in reindeer compared with a pure lichen diet.When the reindeer are exposed to acute starvation, the ruminal microbial environment changes considerably.
To understand the ability of reindeer to adapt to a grass diet in winter, food inrake, digestion, ruminal fermentation and bacterial popularion, gasrrointestinal anaromy and body condition have been investigated in reindeer raken from a narural winter pasture and fed different round baled grass silage qualiries.(paper III, IV, & V).
Well preserved qualities of grass silage, independent of maturity of the plants have been shown to be highly acceptable to reindeer.The silage structure and chemical composition however, seem to influence rhe gasrrointestinal ttact anatomy substantially and hence, the utilisation of the silages.Reindeer easily adapred to high-quality timothy silage with 89% leaves, 38.7% dry matter eel wall content and 30.0%dry matter warer soluble carbo hydrates content.Both summer and winrer the digestibl energy intake was high (range 13.9-17.2MJ/d), reticulo rumen digesta load small (tange 9.6-18.3% of bod mass) and carcass weight high (range 45.8-52.6%o body mass).In reindeer fed fibrous timothy silage witl 27% leaves, 57.8% dty mattet cell wall content am 6.2% dry marrer water soluble carbohydrares content the digestible enetgy inrake was low (range 8.3-9-MJ/d), reticulo-rumen digesra load was great (rang 25.1-33-3% of body mass) and carcass weight was lo\ (range 34.3-42.2% of body mass).This indicate tha reindeer have limitations in utilising toughage with hig fibre content.
Thus, high-quality leaf rich timothy silage seems to b a diet suitable as emetgency food for reindeer.