Table of Contents Preface Acknowledgments I. Introduction II. Utilization of cassava Cassava in African farming and food systems: Implications for use in livestock feeds Cassava in food crop and livestock production systems Cassava in food systems during crisis Importance of cassava in future food systems Implications for cassava use in livestock feed Conclusion An overview of traditional processing and utilization of cassava in Africa Why cassava needs processing Constraints in the traditional processing of cassava Traditional methods for processing cassava Processing techniques and reduction of cyanide in cassava Processed products Processing equipment Storage of processed products Cassava leaves as vegetable Utilization of processed products Modes of consumption Potentials of cassava as animal feed The future of cassava References Utilization of cassava in nonruminant livestock feeds Agronomic and nutritional potentials of cassava Utilization of cassava in poultry feeding Utilization of cassava in swine feeding Future perspective References A review of ruminant responses to cassava-based diets Response of ruminants fed on cassava and its by-products Nutrient content of cassava Utilization of cassava products and by-products by ruminants By-products of cassava tuberous root processing Constraints to widespread utilization of cassava products Future research needs References Effect of protein deficiency on utilization cassava peel by growing pigs Materials and methods Results Discussion References The use of cassava feeding rabbits Cassava root meal Cassava peel meal Cassava leaf meal Effect of processing on feeding value of cassava References The potential of cassava peel for feeding goats in Nigeria Materials and methods Results and discussion References III. Varietal improvement of cassava Cassava varietal improvement for processing and utilization in livestock feeds Quantitative biology of cassava varieties suitable for livestock feeds Biochemical aspects of cassava utilization for livestock Low cyanide cassava varieties References The adoption of improved cassava varieties and their potential as livestock feeds in southwestern Nigeria Cassava varieties in southwestern Nigeria Level of adoption of improved cassava varieties in southwestern Nigeria The sociology of cassava adoption and spread Cassava as a livestock feed resource The economies of cassava as a livestock feed resource References IV. Processing of cassava Processing cassava for animal feeds Processing of cassava into chips and pellets Artificial dryers Processing of cassava leaves and stems Production of single cell protein from cassava References Constraints and projections for processing and utilization of Cassava Mechanized processes of cassava detoxification Utilization of detoxified cassava in poultry feeds Projections Constraints References V. Cassava utilization in selected countries The use of cassava broiler diets in Côte d'Ivoire: Effects on growth performance and feed costs Materials and methods Results and discussion Acknowledgment References Evaluation of cassava energy source in dairy cow concentrate feeds in Kenya Materials and methods Results Discussion References Processing and utilization of cassava livestock feed in Tanzania Cassava production in Tanzania Cassava processing in Tanzania Cassava-based diets for pigs Cassava-based diets for poultry Cassava a feed source for ruminants Present and potential roles of cassava as a livestock feed Why cassava is not widely used for livestock feeding Conclusion References Cassava production and utilization in Liberia Production and processing Research Cassava as animal feed References VI. Reports of working groups and workshop recommendations Reports of working groups Report of working group A Report of working group B Report of working group C Workshop summary and recommendations Summary of workshop Recommendations List of participants Cassava in African farming and food systems: Implications for use in livestock feeds Cassava in food crop and livestock production systems Cassava in food systems during crisis Importance of cassava in future food systems Implications for cassava use in livestock feed Conclusion F.I. Nweke and H.C. Ezumah Farming systems can be broadly defined to include the food system as a subset in the overall context of production of food and shelter materials. The food system may also be defined to include crop and livestock production systems as a subset when it is considered as a continuum of activities starting from production through processing and distribution to utilization of crop and livestock products for food. The importance of the latter definition is underscored by the decision, in 1987, to award the first General Foods World Food Prize, as follows: The concept of the total food chain lies at the heart of the General Foods World Food Prize, for each link in that chain plays a vital role. Every aspect of the production, processing and distribution of food needs to be considered, including farming, the agricultural sciences, food sciences and technology, nutrition, economics, technology transfer, governmental policies, transportation and distribution and education [General Foods 1987]. The General Foods' definition is adopted in this paper and livestock production systems as subsets of food systems. This paper will describe the role of cassava in the food crop product/on systems of tropical Africa. We will also explore the degree to which tropical African countries can meet their cassava needs for human consumption and generate a surplus for use in livestock feeds. In collaboration with international Center for Tropical Agriculture (CIAT), Colombia, the Overseas Development Natural Resources Institute (ODNRI), and national agricultural research systems (NARS) in Africa, IITA has embarked on a continent-wide survey of cassava in Africa. The survey is called the Collaborative Study of Cassava in Africa (COSCA) and it is initially concentrated in six countries namely, Côte d'Ivoire, Ghana, Nigeria, Tanzania, Uganda, and Zaire, selected partly on the basis of the importance of cassava in the farming and food systems of the countries. The survey data were analyzed on the basis of production projections using time series data provided by USDA as well as other secondary data. Cassava in food crop and livestock production systems The interrelationships between crop-based production systems and livestock-based systems are illustrated in figure l, which shows a complex eastern Nigeria system, in which the family household is the major source of labor used for food crop and livestock production. Figure 1: Interaction of crop and animal farming In a cassava-based system (adapted from Lagemann 1977) In this food crop system, cassava is commonly intercropped with early maturing annuals such as maize, and vegetables like okro, egusi and bitter leaf. The crops intercropped with cassava in different parts of Africa very with regions of growth and food preferences. In Zaire, the intercrop may be dominated by grain legumes such as groundnuts and phaseolus beans, while in Sierra Leone, The Gambia, Liberia, and Guinea, rice is the dominant intercrop. Protected trees like Parkia , and nonwoody perennials such as plantains and bananas, are also frequently grown in patches or as individual stands in cassava fields. While cassava and associated crops are the main food crops, trees provide fuelwood and construction materials. Dry cassava peels are fed to goats and sheep, and pigs eat the tubers. In some countries, cassava leaves are consumed by humans and also fed to animals, or used as poultry rations. These animals provide the household with eggs and meat for consumption and the market. Animal wastes are incorporated with household refuse as mulch and used for soil enrichment or are carted directly into herds, especially those close to homes. Some existing cassava cropping patterns modified to incorporate only two crops are illustrated in figure 2. Pattern 2 is common in Zaire and some countries in West Africa while pattern 4 is dominant in West Africa. Subsidiary crops associated with these patterns may be fruits and leafy vegetables. Patterns 1 and 3 are further modifications of the traditional, complex crop mixture systems to nearly monocrop pattern (1) and a completely monocrop pattern (3). Soybean may be intercropped with cassava as in patterns 1, 2 or 4. Cassava is highly compatible as an intercrop with these annuals because of its slow initial growth, especially between planting and six to eight weeks of growth. The annuals which grow faster during the initial growth phases rarely compete adversely with cassava and have been shown to smother weeds. The advantage of soybeans, a relatively new crop in cassava growing areas of Africa, is that it will supply the deficient protein component to a predominantly cassava diet in both human food and animal feeds. Figure 2: Cassava cropping patterns and alternative patterns for humid southern Nigeria Cassava in food systems during crisis The role of cassava in food systems will depend on what happens to real income. Cassava is a crisis crop. In times of war, drought or low national incomes, cassava consumption increases relative to alternative food staples such as yam, maize, rice, and wheat. Cassava in certain forms is a low income consumers' staple. Although an individual may not increase the quantity of cassava consumed in a year, as national income declines, annual average cassava consumption per person increases because more people begin