Performance of domestic herbivores in marginal heathlands
In the north-west of Spain, on a marginal mountain area located at 850-950 m.a.s.l. and dominated by heather species (Erica umbellata, Erica cinerea, Calluna vulgaris), non-lactating goats, ewes, cows and mares were managed for spring-summer grazing during two years (2006-2007). The objective was to study diet selection and live-weight (LW) changes in these animal species. The results show differences in the diet components and in the individual LW changes between these herbivores. Horse was the animal species with higher ability to modify the diet composition according to the changes in vegetation, while cattle and goats only showed minor changes. In both years, cows lost weight in any period of the grazing season, at an average of 0.48 kg/day. However, mares increased LW during the first period (June-July) and lost in the second (August-September), maintaining LW (0.04 kg/day) for the overall grazing season. There were also some differences between the small ruminants. Both sheep and goats increased their LW during the first period, although goats did it at a higher degree. By contrast, in the summer both species lost weight, though the losses tend to be higher in ewes. Thus, in the overall spring-summer grazing, goats were able to increase their LW at 10 g/day while sheep lost 10 g/day (P<0.01). Therefore, areas with improved pasture are necessary for productive animals to maintain or increase their LW, to extend the grazing season, and to achieve the sustainability. The demand for this improved pasture is considerably higher in cattle than in the other species.
Keywordsanimal performance herbivores diet composition heathland
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