During the past two decades or so, rural population in Africa has increased slowly while urban population
has grown dramatically. The hugely increased urban demand for cereals and pulses (which produce crop
residues for livestock) and for livestock products is now the main force stimulating mixed farming systems
in the semi-arid and sub-humid areas of sub-Saharan Africa. Grazing land has diminished, crop residues
are becoming a more important element in raising livestock and fattening penned livestock has become
profitable. The changes in land use, land tenure and the shift of livestock raising southwards in West
Africa are illustrated. Farmers’ adaptation to rapidly changing markets for their products and the factors
of production are illustrated with examples from Senegal, Nigeria, Niger, and, by way of contrast, Kenya.
The main challenges this sets to agricultural scientists are described. The livestock element in mixed
farming system now requires careful economic analysis and participative research if scientists are to meet
the evolving needs of farming as the urban sector enlarges.