The role of the integrated soybean-maize-chicken value chains in sustainable food systems in the Southern Highlands of Tanzania

Wilson Charles Wilson

Research output: Thesisinternal PhD, WU


Tanzania is among the sub-Saharan African countries experiencing food insecurity due to high rates of malnutrition in many forms, largely attributed to a lack of dietary diversity among disadvantaged urban and rural households. Surprisingly, Tanzania's breadbasket regions important for food production have high rates of micronutrient deficiency, partly due to limited dietary diversity. This thesis focused on exploring the potential of soybean-maize-chicken value chains to support the sustainable production of diversified diets and to identify entry points for value chain integration in the Southern Highlands of Tanzania. We first employed fuzzy cognitive mapping (FCM) to understand the current soybean, maize, and chicken value chains, highlight stakeholder relationships, and identified entry points for value chain integration to support nutritious diets in three regions in the Southern Highlands. The study revealed the importance of networks of value chains in domestic markets, whereby soybean-maize-chicken value chains are interconnected particularly at smallholder farming systems and at processing facilities. Chicken feed was an important entry point for integrating the three value chains, as maize and soybean meal are chickens' main sources of energy and proteins. Unlike maize, the utilization of soybean in chicken feed was very low, mainly due to inadequate processing of soybean grain into meal. As a result, the soybean grain produced is primarily exported to neighbouring countries for processing, and soybean meal is imported at relatively high prices. We proposed enhancing local sourcing and adequate processing of soybean coupled with strengthening the integration of smallholder farmers with other soybean-maize-chicken value chain actors to improve access to nutritious food for people.

In a next step, we conducted a cross-sectional survey to understand the diversity of chicken farming and to explore the intensification gradient in the production systems in urban and rural areas in the Iringa region. This study is the first to explore the diversity of chicken farming and the underlying production constraints based on the subdivision of the production systems refined by adding the size of the flocks to highlight variations in the scale of operations. The findings show that the degree of intensification of chicken production systems was increasing with the number of improved crossbred and exotic chickens raised at medium to large scale intensive systems, in both urban and rural locations. These chickens were fed with homemade and/or commercial feeds. Understanding the diversity of chicken farming systems allowed a diagnosis of problems targeting interventions for different production systems. We found for instance that development of small-scale poultry systems is hampered by limited access to quality feed whereas medium to large scale systems were constrained by limited supply of one-day-old chicks.

The study further explored the current feed gap and how this gap can be closed by comparing the actual feed quantity and quality supplied to dual-purpose chicken with the recommended standards. Combining surveys, physical measurements of chicken and eggs, sampling of feed and laboratory analysis on micronutrient content and mycotoxin contamination, we found the need for a stronger focus on feeding strategies and ensuring the availability of affordable, suitable and safe feed formulations. In line with the Tanzania Livestock Master Plan, the study highlighted the importance of closing feed gaps (both with regard to quantity and quality) to meet the increasing demand for chicken meat and eggs.

Lastly, the study assessed land requirements to produce sufficient food of adequate nutritional quality for the current and the anticipated doubled population of the Iringa region by 2050 based on macro secondary data, and micro primary data. The actual and potential yield of the food crops grown in the region were extracted from the Yield Gap Atlas, a global open-access database. For actual chicken production, we used our own data and potential yields, and feed requirements were based on values provided by poultry breeding companies. The findings of this thesis revealed that with actual yields for crops and poultry and a doubling in population size, even the total area of land suitable for agriculture is not enough to produce sufficient food and feed. Cultivating unused suitable or unsuitable land with the actual yields leads to food-feed competition in most scenarios and with the increasing population, food exports will be strongly reduced or no longer possible. To meet the increasing demand for food, the present study strongly recommends focusing on sustainable intensification options aiming to reduce the yield gaps in crop and poultry production. Otherwise, with the current yield, it will not be possible to produce sufficient diverse food for the current and future population without further expansion of agriculture.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • Oosting, Simon, Promotor
  • Giller, Ken, Promotor
  • Slingerland, Maja, Co-promotor
  • Baijukya, F.P., Co-promotor
Award date14 Jun 2023
Place of PublicationWageningen
Print ISBNs9789464476446
Publication statusPublished - 14 Jun 2023


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