FORAGE PRODUCTION AND UTILIZATION IN VARIOUS TOPOGRAPHIC ZONES OF THE FESCUE GRASSLANDS

Abstract

The effects of topography and litter on forage production and utilization were studied on Rough Fescue Grasslands in the foothills region of southwestern Alberta. Forage production and utilization were estimated, at monthly intervals during the grazing seasons over 4 yr, in six topographic zones of two fields stocked at a moderate or a high rate representing 2.4 or 3.2 animal unit months per hectare (AUM ha−1), respectively. The higher rate could not be achieved in the first 3 yr of the study because available forage was limiting. The topographic zones were represented by the west, east, south, and flat aspects of the upland areas, and by the lowland zone subdivided into a subirrigated zone and the interface between the latter and upland zones. Forage production was about 50% more in the subirrigated zone than in the upland zones. Among the upland zones, forage production tended to be greatest on the south aspect. Forage utilization was greatest in the subirrigated zone but least on the south aspect. Topographic preference was highest for the subirrigated zone early in the grazing season. The effect of a high stocking rate was to minimize the preference differences among topographic zones. Litter had a significant positive effect on both forage production and the amount of residual forage after the grazing season but had a significant negative effect on percent utilization. Litter provided a buffer which enabled the maintenance of anticipated stocking rate by providing emergency forage and enhancing production during drought. Key words: Litter, residual forage, preference, aspect, stocking rate, cattle, distribution