Because nutritional requirements of muskoxen (Ovibos moschatus) in win
ter are poorly understood, we compared voluntary intake and apparent d
igestibility of low-protein grass hay by 5 mature muskoxen and 3 matur
e Hereford cows during late winter 1993. We hypothesized that muskoxen
would digest poor quality graminoid forage more completely and mainta
in mass at lower rates of intake than would cattle, on the basis of ev
idence of relatively low intake and relatively complete digestion of g
ood quality diets by captive muskoxen during winter (White et al. 1984
, Adamczewski et al. 1994). Hay was 6% crude protein and 74% neutral d
etergent fiber and was similar in composition to sedge (Carex spp.) an
d grass (e.g., Kobresia spp.) samples from feeding craters of muskoxen
on Banks and Victoria islands, Northwest Territories (NWT). Both spec
ies maintained body mass on the experimental diet but daily intake of
dry matter by muskoxen was only 1/3 that by cattle (32 +/- 2 [SE] vs.
96 +/- 3 g/kg0.75; P < 0.001). Apparent digestibility of organic matte
r, measured using chromic oxide, was higher in muskoxen than in cattle
(58 +/- 2 [SE] vs. 50 +/- 3%; P = 0.03). Muskoxen are well adapted to
digesting low quality graminoid forage and maintaining mass at low ra
tes of intake, and these traits likely contribute to their success in
surviving long arctic winters.