Organic matter intake, diet digestibility and feeding behaviour of goats, red deer and South American camelids feeding on three contrasting Scottish vegetation communities.
Abstract
With changes in the agricultural policy for rural areas in the UK, there is increased pressure to develop management protocols for indigenous and sown swards based on grazing by ruminant species other than sheep and cattle, e.g. goats, red deer (Cervus elaphus) and South American camelids (Lama guanicoe). This paper describes the organic matter intake, diet digestibility and activity time of these animal species grazing three vegetation types typical of upland ecosystems in Scotland: a sown grassland (Lolium perenne-dominated), an indigenous grassland (Nardus stricta-dominated) and a dwarf-shrub community (Calluna vulgaris-dominated). Intake and digestibility of organic matter (OM) were measured by the n-alkane technique, and activity time was measured using vibracorders. For all species OM digestibility of the diet was higher on the sown sward than on the indigenous communities, and higher on the indigenous grassland than on the dwarf-shrub community. There were no consistent patterns to between-species differences in OM digestibility. When expressed on a metabolic liveweight basis, there was no consistent pattern to the seasonal differences in OM intake (OMI) between species or within species between vegetation types. Irrespective of season, grazing session or vegetation type, activity time of the goats was significantly lower than that of either the red deer or camelids. It is concluded that these animal species differ in their foraging strategy, particularly on indigenous communities where heterogeneity in resource dispersion and availability is higher. Goats and camelids maintain diet digestibility at the expense of intake, whereas red deer maintain intake.