[Economic analysis of marginal management arrangements for sheep. Comparison of different overwintering alternatives, a.o. plastic house and spruce forest]

aliment pour animaux alojamiento de animales animal housing costos costs crianza extensiva economic analysis extensive husbandry farm management farm results feeds forest grazing gestion de l'exploitation agricole hivernage logement des animaux manejo de fincas noruega norway ovin ovinos pastoreo en el bosque piensos plastics rendement rendimiento sheep wintering yields