Intake, digestibility, methane and heat production in bison, wapiti and white-tailed deer

A 3 x 2 factorial experiment was conducted in which the digestibility of alfalfa pellets and methane and heat productions were measured in bison, wapiti and white-tailed deer in February/March 1995 and in April/May 1995. Voluntary dry matter intake (DMI) while animals were individually fed averaged 70, 87 and 68 g kg(-0.75) d(-1), respectively (P = 0.05), and was generally higher in April/May than in February/March. Corresponding organic digestibilities were 52.9, 54.1 and 49.1% (P = 0.10). There was also a trend (P < 0.1) for fiber digestibilities to be lowest for deer. Methane production (L kg(-1) DMI), was 30.1, 23.5, and 15.0 L kg(-1) for bison, wapiti and deer, respectively (P = 0.01), with more (P < 0.01) methane being produced in February/March than in April/May (28 vs. 18 L kg(-1) DMI). No differences in heat production (kJ kg(-0.75)) Or estimated energy requirements for maintenance could be detected between species, although animals numerically produced 40% more heat (881 vs. 632 kJ kg(-0.75), p = 0.13) in April/May when feed intakes were higher than in February/March. It was concluded that DMI of native ungulates is higher in spring than winter and that methane emissions per unit feed consumed were the highest with bison and the least with white-tailed deer.