In both Africa and Tropical America (the two project areas) major constraints to livestock production are the supply and quality of feed, especially during the dry season: in Sub-Saharan Africa, more than half of about 60 Diagnosis and Design exercises conducted by ICRAF have identified shortage and poor quality of dry season fodder as the biggest problem facing small-scale farmers, but it is often marginal in economic terms and may involve unsustainable land use practices, causing erosion on sub-humid hillsides. The three main limitations to increased productivity of dual purpose cattle systems have been identified as supply and quality of feed, the milk potential of cows, and overall management.

A further problem is that large areas of the tropics have acid infertile soils, to which few forage legumes are well adapted. Calliandra calothyrsus Meissin is a Central American tree legume which is attracting increasing attention as a forage throughout the humid and subhumid tropics owing to its fast growth and its tolerance of soils with low pH and high aluminium saturation. Reports of its feeding value vary widely, however, and its nutritive value declines rapidly on drying, constraining its use in cut-and-carry-systems.

Strategies to improve seasonal availability of livestock feeds in high potential areas developed and promoted. This purpose will be addressed with specific reference to Calliandra calothrysus, and strategies to optimise its fodder value.

• Effects of environment, management and provenance on nutritive value of Calliandra forage determined with respect to:
• Utilisation by small ruminants
• Crude protein (CP), organic matter (OM), in vitro and in sacco digestibility and gas production profiles.
• Degradability of greenhouse - field-grown Calliandra leaf samples compared: if comparability good, effects of drying Calliandra leaves on degradability, and the role of tannins in these effects, investigated.
• Complimentarity of Calliandra to low quality based feed elucidated.
• Results from outputs above used to formulate improved utilisation strategies, and disseminated.