Hoffmann (1968, 1973, 1984, 1989) classifed Alpine ibex as a typical grazer with a certain degree of selectivity. Alpine ibex have an almost completely herbaceous diet (representing from 82 to 94.4 % of the rumen content - Tataruch & Klansek, 1987; Tataruch et al., 1991), based primary on graminaceous plants (60%) and dicotyledons (38%); while wooden species are limited to the minimum (about 2 %) (Houte De Lange, 1978; Klansek & Vavra, 1992). Selection in favour of herbaceous species has been confirmed by the comparison of available and consumed food resources (Vavra & Klansek, 1992). Different age classes appear to have a similar behaviour of food selection (Klansek & Vavra, 1992).
Graminaceous plants appear to be important at most during winter, particularly those belonging to the genus Festuca (Festuca ovina, F. rubra, F. pumila ), even if Alpine ibex eat them all year round, together with those belonging to the genra Phleum, Sesleria, Calamagrostis, Agrostis, Avena, Trisetum, Koeleria, and Poa. All the following herbaceous species appear to be also part of the diet of Alpine ibex (Couturier, 1962; Burthey, 1987; Peracino, 1995a e b): Cyperaceae of the genus Carex, Schoenus, Kobresia; some Juncus and Luzula; Papillonaceae (Onobrychis, sp); Ranunculaceae (Pulsatilla alpina, Thalictrum foetidum, Ranunculus glacialis); Poligonaceae (Oxiria digyna, Rumex scutatus, Polygonum viviparum); Leguminosae of the genra: Trifolium, Anthyllis, Lotus, Astragalus, Oxitropis; some Umbelliferae and Compositae of the genra: Achillea, Aster, Erigeron, Tanacetum, Carduus, Carlina, Cirsium.

In winter and spring Alpine ibex feed also on braches and leaves of little bushes (Vaccinium mirtillus, V. uliginosum, Arctostaphylos uva-ursi, Loiseleuria procumbens, Salix erbacea, S. retusa, S. helvetica, Rhododendron ferrugineum); little branches, gems, tender leaves and bark of Corylus avellana, Berberis vulgaris, Juniperus communis, Alnus viridis; mosses and lichens; needles and barks of young Larix decidua, Pinus mugo, P. cembra and, where present,, Abies alba e Picea excelsa.
The kind of diet described and behavioural observations, confirm that only rarely Alpine ibex use the wood as a food resource (Colle et al., 1974; Klansek & Vavra, 1991; Tataruch et al., 1991).

Thus, in optimal habitats, the reported damages to wood plants are modest and mostly due to scratching and tramping (Campell, 1958; Houte De Lange, 1978; Holtmeier, 1969).
The effects of browsing are observed mostly during very snowy winters, affecting particularly the Stone pine Pinus cembra (Holtmeier, 1969; Ratti, 1984). These effects are particularly seen in transition zones between wood and alpine meadow, and in reforestation zones (Wiersema, 1989).

Faecal nitrogen analyses (especially NDF and ADF) have shown that, form a nutritional point of view, the most important period is the summer months going from May to August and that the percentage of proteins decreases severely from September onwards. The quality of diet appears in fact to be related positively to the mean monthly temperature and not with the mean height of the snow on the soil (Bassano et al., 1997a). The analysis of the digestibility of dry food resources (hey and pellets) by Alpine ibex in captivity has shown that this species is particularly adapted to consume diets rich in fibre, with a consume of about 2.7% of the animal's body weight (Bassano et al., 1999). These investigations on the energetic demands of Alpine ibex, have been useful also to estimate the carrying capacity of the areas used by the species (Bassano et al., 1998).

The nutritional value of the winter diet of Alpine ibex appears to be insufficient to cover the energetic demands of an adult animal (Bassano & Bergero, 1999). This results show that more research is still needed on the real significance and importance of winter terrain and on the survival strategies during winter in this species.