Diet composition of guanacos (Lama guanicoe) and sheep (Ovis aries) grazing in grassland communities typical of UK uplands

A study was undertaken to compare the diet composition of guanacos (Lama guanicoe) and sheep (Ovis aries) when pastured on improved and unimproved Agrostis spp./Festuca spp. dominated grassland typical of the UK uplands. Samples were collected from oesophageal fistulated guanacos and sheep grazing experimental plots that had been grazed previously by either sheep or guanacos. Sward composition and herbage biomass were determined for each plot using quadrat cuts. The sward composition and diet composition results obtained were used to calculate selectivity indices for individual dietary components. Green leaf of broad-leaved grasses was the main dietary component for both animal species on both the improved and unimproved grasslands. In general, the guanacos consumed less green grass leaf and more dead grass leaf than the sheep. Their diets also contained significantly more Nardus stricta than sheep diets. The sheep diets contained significantly more Trifolium repens, which was consistently avoided by the guanacos. Only one dicotyledonous species (Cirsium palustre) was consistently selected by the guanacos. There were fewer between-species differences in diet composition on the previously sheep-grazed plots than on the previously guanaco-grazed plot