Browsing Journal of Range Management, Volume 51, Number 5 (September 1998) by Subjects
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Forage selection by cattle on fescue prairie in summer or winterThe rough fescue grasslands are important for livestock grazing as well as other values such as wildlife habitat, recreational opportunities, and watershed properties. The impact of livestock on these grasslands must be better understood in order to manage grazing for optimal use of the resource. A study was conducted from 1992 to 1994 on the rough fescue grassland near Stavely, Alberta, to determine forage selection by cattle in the winter and summer and the effect of canola supplementation on forage selection. Twelve 1.7-ha paddocks were stocked with 2 cows (Hereford) at 3.2 animal-units-months ha-1 in winter; canola supplements (0.0, 0.4, 0.8, and 1.2 kg animal-1 day-1) were applied in a randomized complete block design. Three additional 1.7-ha paddocks were similarly stocked but grazed in the summer with out canola supplements. Forage availability, utilization, and relative preference were estimated for 4 major plant species. In both winter and summer, rough fescue (Festuca campestris Rydb.) was utilized most (P < 0.05) and Idaho fescue (Festuca idahoensis Elmer) and smooth aster (Aster laevis L.) were utilized the least. Of total forage utilized, rough fescue and Parry oat grass (Danthonia parryi Scribn.) contributed about 90 and 9%, respectively, in winter and about 62 and 32%, respectively, in summer. In summer, Parry oat grass was utilized in proportion to its availability. Rough fescue was the preferred species in both winter and summer. Percent forage utilization in winter was not affected by supplementation with canola. The high preference for rough fescue appeared to be determined by the accessibility of the large tufted plants to cattle. This was particularly evident in winter when access to plants was impaired by snow cover. Successful winter grazing on these grasslands is enhanced with a large proportion of rough fescue plants in the stand.
Simulated cattle fever tick infestations in rotational grazing systemsPrior simulation analysis of cattle fever tick population dynamics has indicated that fixed rotation, short duration grazing (SDG) systems could mediate the spread of ticks among pastures if rest periods were greater than 100 to 150 days. A question arose whether variable rotations with rest periods approaching 35-70 days could mediate the spread of ticks within these rapid, rotational grazing systems. An 8-pasture:1-herd extensive (26-34 days:182-238 days graze:rest) and intensive (5-10 days: 35-70 days graze:rest) short duration grazing system was simulated over a 2-year period after a spring and fall introduction of infestated animals using a model depicting both temporal and spatial processes involved in host-parasite-landscape interactions. The extensive SDG system was infested for 639 and 424 days for spring and fall introductions, respectively. The intensive SDG system was continuously infested throughout the 24-month simulation. Although the intensive SDG system was continuously reinfested, there were more frequent tick-free periods in the fall introduction than the spring introduction. These simulations indicate that rest periods exceeding 150 days are necessary to minimize the rate and extent of spread of ticks in variable rotational grazing systems. These considerations are pertinent to the goals of both control and eradication strategies.