The incorporation of livestock into alley farming systems, in which food or forage crops are grown between hedges of multipurpose trees that are regularly pruned for mulch and/or forage, has been studied for over 10 years in Africa. Prunings from leguminous trees such as Leucaena and Gliricidia can be used for mulch, increasing crop yields, but the trees may also be pruned for fodder, especially during fallow periods. The major benefit from supplementing the diet of free-roaming small ruminants in West Africa with the foliage of leguminous trees is increased survival, and the forage is best directed at late pregnant and lactating females. In East Africa crossbred dairy cows show a significant response in milk production to supplementation with Leucaena. Economic analyses of livestock production show that continuous alley farming is more profitable than alley farming with fallow, or conventional no-tree farming, even when the cost of clearing trees at the end of their useful life is included.