Abstract: A material formed from plant matter granules has the following size distribution, the percentages being expressed by weight of dry matter: between about 5 and 50% of the granules having a size of less than about 0.25 mm, between about 5 and 40% of the granules having a size of between about 0.25 and 0.5 mm, between about 15 and 60% of the granules having a size of between about 0.5 and 1 mm, between about 1 and 10% of the granules having a size of between about 1 and 1.25 mm, between about 0.5 and 7% of the granules having a size of between about 1.25 and 1.4 mm, between about 1 and 10% of the granules having a size of between about 1.4 and 1.7 mm, between about 0.1 and 10% of the granules having a size of between about 1.7 and 2.36 mm, and between about 0 and 10% of the granules having a size greater than about 2.36 mm.