Montanera is a traditional feeding system where pigs forage for acorns. Iberian pigs foraging for acorns during their finishing phase has economically contributed to conserving the “dehesa”, a high nature value (HNV) farm-land based on agroforestry, currently consisting of more than four million hectares in the southwest of the Iberian Peninsula
This natural resource is used to fatten pigs without any kind of compound or supplementary feed. During the last 2-3 months of fattening, pigs can gain more than 40 kg of body weight from grass and foraged acorns.
- The fattening performance is very much influenced by the age of pigs and their compensatory growth; hence, pigs should be as old as possible (≥1 year) and adapted to grazing.
- Grass is necessary as a source of protein to compensate for the low protein levels in acorns.
- The food conversion rate is 10.5 kg of whole acorns of Q. i. rotundifolia to gain 1 kg, besides the contribution of grass; to establish the stocking rate, consider that an adult evergreen oak produces ≈11 kg of acorns/year).
- Iberian pigs peel acorns to avoid the high content of tannins in the shell. However, during peeling, approxi-mately 20% of the kernel can be wasted.