Relationship of dietary browse to intake in captive muskoxen

Abstract

The effect of dietary browse (Salix bebbiana Sarg.) on intake and activity of muskoxen (Ovibos moschatus Zimmermann) pastured in south-central Alaska was compared to animals on grass pasture only. In previous work, intake increased in penned animals fed increasing browse: hay rations, which presumably allowed for increased weight gain and wool fiber (qiviut) growth. Eight mature steers were divided into 2 treatments: 8 hours daily ad libitum access to browse plus pasture grass (Bromus inermis Leyss., Poa pratensis L. mix) or pasture grass only. Animals were placed in adaptation enclosures 10 days before each trial. Bundles of browse were tied to perimeter fences. Trials were conducted 3 times during the 1992 growing season. For the trials, animals of like treatment were placed in each of four 0.33 ha trial enclosures for 8 hours, every other day, for 6 days (3 trial days). Activity budgets were calculated using scan sampling. Hand-harvested simulated bites were weighed to determine bite size, an bite rate was calculated using focal sampling techniques. Intake was calculated as a function of bite size, bite rate, and time spent foraging. Intake was greater (P = 0.064) for animals with access to browse. Digestive physiology of mukoxen may have favored higher intake of a mixed grass-browse diet over grass alone. Previous data suggest that elevated intake increases weight gain and qiviut growth.