On the traditional silvo-pastoral system of Alentejano pigs (Montanheira in Portugal and Dehesa in Spain), acorns are a fundamental source of energy for the fattening period and are complemented with the protein from the available pasture, under the oak canopy.

Montanheira lasts from October to February, while there are acorns available, and these establish the basis for the calculation of stocking rates (1 pig to 1,5-2 ha).

Although the chemical composition of these feeds (acorns and pasture) is well documented, their is a lack of knowledge about their intake and digestibility, mainly due to the absence of tested methodologies in pigs. It is well known that, in years of dry Autumns, and therefore pasture scarcity, the animals will not grow and toxicity symptoms may occur due to the tannin content of acorns.

However, the relevance of the pasture as a source of nutrients and/or a detoxification factor of the tannins from acorns, is not quantified.

A better knowledge of the role of pasture in the nutritional status of the animal and intake, digestibility and diet composition allowed a more rational utilisation of the natural resources and will contribute to an optimisation of the production system of Alentejano pig.

This project studied the effect of pasture intake and diet digestibility on growth rates and carcass composition of Alentejano pigs under Montanheira.

Estimates of intake, digestibility and diet composition was carried out using the n-alkane technique. Micro-histological analysis of the faeces produced by the animals and feeding behaviour studies will also be carried out, to combine the data produced with the estimates of intake and diet selection by the n-alkane technique.