ARCTIC Digestibility of Plants in Ruminal Fluids of Barren-Ground Caribou

• Main Authors: Donald C. Thomas, Peter Kroeger
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Northwest Territories; Canada; Territoires du Nord-Ouest
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.545.4618; http://pubs.aina.ucalgary.ca/arctic/arctic34-4-321.pdf

ABSTRACT. The comparative digestibilities of plants and their rates of digestion in vitro were assessed by fermentation with ruminal fluids obtained from barren-ground caribou (Rungifer rurundus groenlundicus) shot on their winter range in the southern Northwest Territories. There was a near-linear increase in the in vitro, dry-matter disappearance (IVDMD) with fermentation time (30-120 h) for all eight lichen species that we tested. In contrast, IVDMD was essentially maximal after 60 h fermentation for 10 of 11 non-lichen species. The green leaves of Carex rosrruru and Equisetum vuriegurum were the only species with IVDMDs higher than 50 % after a 60-63 h fermentation period. The two species of mosses and a liverwort were poorly digested (15-27%). The addition of 63 mg of urea to each tube markedly increased the digestibilities of both species of lichens tested, and that of Vuccinium vitis-idueu, but it lowered the IVDMD of Salix and Betula stems and the green and cured parts of Carex rosrruru. The IVDMDs of four lichen species collected on the Canadian Arctic Islands were higher than those of eight terricolous species obtained from the mainland winter range of R.r. groenlundicus. Key words: Rungifer, caribou, in vitro, digestibility, forages, lichens, rates, Canada RfiSUME. La digestibilitt comparative de plantes et leur taux de digestion in vitro ont t t t Bvaluks par la fermentation de fluides ruminaux obtenus de caribous des landes (Rungifer rurundus groenlundicus) tirts dans leur habitat hivernal dans le sud des Territoires du Nord-Ouest. I1 y a eu une augmentation quasi-lintaire de la disparition in vitro de matibre sbche (DIVMS) avec un ptriode de fermentation (30-120 h) pour les huit especes de lichens mises B I’tpreuve. Par opposition 8 ceci, la DIVMS Btait essentiellement maximale aprbs une fermentation de 60 h dans 10 des 11 espbces de non-lichens. Les feuilles vertes du Curex rosrraru et de 1’Equiseturn vuriegutum ttaient les seules espbces