Bison and cattle digestion of forages from the Slave River Lowlands, Northwest Territories, Canada.

Dry matter disappearance (DMD) of native forages collected from the Slave River Lowlands (SRL), Northwest Territories, was consistently greater in bison (Bison bison) than in Hereford cattle (Bos taurus) when measured with a nylon bag technique. Overall average DMD values were 52% and 39% for bison and cattle, respectively. Mean percent DMD values for each plant species were: willow (Salix spp.), 56; slough sedge (Carex atherodes), 50; baltic rush (Juncus balticus), 47; aleppo avens (Geum aleppicum), 44; and northern reedgrass (Calamagrostis inexpansa), 39. Dry matter disappearance was inversely correlated (P 0.05) in DMD between two bison fed the hay ration and two fed hay plus the supplement. The Slave River Lowlands (SRL) (approximately 600 to 610 N latitude; 1 120 to 1 130 W longitude) is the home range of approximately 400 wild bison. An assessment of this area as range for bison and cattle was undertaken because of its importance to bison and because of a growing interest in the potential of this area as cattle range (Reynolds et al. 1978). Too few data are available for making empirical comparisons of digestibility between bison and cattle. Comparative data on the digestion of grass, sedge, and alfalfa hays of bison, yak, and cattle were reported by Richmond et al. (1977). Peden et al. ( 1974) compared the digestibilities of forages grazed by bison and cattle using a nylon bag technique. This technique has been useful for ranking the digestibilities of different feedstuffs (Figroid et al. 1972; Kercher et al. 1964), assessing the effect of different rations on digestibility (el-Shazly et al. 1961; Neathery 1969) and comparing the digestive capacities of animal species (Peden et al. 1974; Van Dyne 1962). The objectives of the present experiment were (1) to compare the digestibilities of native forages from the SRL, (2) to compare the digestive capacities of bison and cattle, and (3) to compare the effects of feeding a roughage as opposed to a roughage and concentrate ration on these digestibilities. The nylon bag technique was therefore well suited to our needs Authors are wildlife biologist, Alberta Environmental Centre, Vegreville, Alberta; research scientist, Canadian Wildlife Service, Saskatoon, Saskatchewan; biologist, Canadian Wildlife Service, Edmonton, Alberta, and assistant professor, Department of Animal Science. University of Maryland, College Park. The authors gratefully acknowledge the assistance of R.M. Hansen, Range Science Department, E. Keith and R. Souther, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, and the statistical assistance of G.E. J. Smith, Canadian Wildlife Service, Ottawa, Ontario. We also thank R.H. Russell and M.C. S. Kingsley, Canadian Wildlife Service, Edmonton, Alberta, for their valuable reviews of this manuscript. Analyses of sample ether extract and crude fiber contents were conducted by the Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, and the Alberta Soil and Feeding Testing Laboratory, Edmonton, respectively. The study was supported by Canadian Wildlife Service Contract No. 0SZ5-0285. Manuscript received August 14, 1979. and was chosen to make these comparisons. Materials and Methods Samples of native forages were collected in the SRL in February and June, 1975. Summer samples of willow consisted of approximately equal dry weights of leaves and twigs from the terminal 12 cm of the twigs. Winter willow samples were comprised of twigs only. Herbaceous plant samples included the entire aerial portion of the plant cut at approximately 2 cm above ground. All samples were air-dried and ground through a I-mm mesh screen. Nylon bag digestibility experiments were conducted using two ruminally fistulated adult Hereford cattle and four ruminally fistulated adult bison at the Pawnee Site, International Biological Program, Nunn, Colorado, during January 1976. One Hereford and two bison were fed crested wheatgrass hay containing 6% crude protein (CP) (Table 1). One Hereford and two bison were fed Table 1. Animals used in nylon bag digestibility experiments.