Metadata only record In many tropical areas the main constraint to increased output of livestock products is the inability of producers to feed animals adequately throughout the year. Yet opportunities exist to enhance ruminant livestock feed supplies by using crop residues, such as cereal straw and legume haulms. Greater emphasis is therefore now being placed on vegetative production in plant breeding research. Crop residues also play an important role in conserving soil moisture, preventing erosion and providing products such as fuel or thatch for smallholders.