The olive tree (Olea europaea L.) is a slow growing evergreen tree that reaches a height of 5-10 m. It is an emblematic tree of the Mediterranean basin. It has a rather shallow root system. The trunk is erect, deeply fissured and distorted. The leaves are simple, lanceolate, 3-9 cm × 0.5-3 cm, leathery, dark grey-green and glabrous on the upper side, and densely covered with silvery scales underneath. They are covered by a cuticle that prevents dehydration. The tree shed its leaves once every three years. The inflorescences are 3-8 cm long, many-flowered, borne on the leaf axils. Only 1-5% of the flowers develop into fruits. The fruit is a drupe containing a fleshy mesocarp (pulp) and a woody endocarp (stone or pit). The pulp contains some 20% oil and is highly bitter due to its high tannin content. The tree starts producing fruits between 4 and 7 years after propagation, through cuttings or suckers. It remains productive for up to 50 years and its life-span may reach 500 years (Ecocrop, 2010; Ecoport, 2010; van der Vossen et al., 2007).
Olive trees are mostly cultivated for their edible fruits from which olive oil can be extracted. There are about 2000 cultivars that can be divided into 3 groups: cultivars for oil extraction, cultivars for table olive production and dual-purpose cultivars (Ecocrop, 2010; Ecoport, 2010; van der Vossen et al., 2007). Olive fruits can also be eaten after soaking. Fruits yields vary from 1 to 10 t/ha depending on cultivation conditions (traditional olive groves or irrigated well-managed commercial plantings). However, there is always considerable year-to-year variation in productivity. One hectare produces 350-400 kg olive oil. Olive oil has recently received renewed interest because of its potential health benefits, as it contains unsaturated fatty acids and small amounts of polyphenols, tocopherols and sterols (Ecocrop, 2010).
In 2009, the world production of olive oil was almost twice (2.91 million tons) that of 1995 (1.65 million tons). The Mediterranean countries account for 98% of total olive oil production. Spain, Italy and Greece are the main producers: 75% of the total production (FAO, 2010). Spain, the USA and Greece are the top producers of olive fruit. World table olive production is 1.1 million tons and represents 8% of total olive fruit production. Main table olive producers are Spain, the USA, Turkey, Morocco, Syria, Greece and Italy (van der Vossen et al., 2007).
Olive by-products are commonly fed to livestock. For further information about by-products of olive oil processing, see the datasheet Olive oil cake and by-products. Olive forage is relished by cattle, sheep, goats and camels (Le Houérou, 1980). It can be browsed by livestock or cut and brought fresh to livestock after pruning.