1.1 Background Livestock are a resource of significant benefit to society in the form of food, income, nutrients, employment, insurance, traction, and clothing (Herrero et al., 2013). By 2050, the total demand for meat, milk and eggs is projected to almost double mostly in the developing world due to population growth, urbanization, income increase and change in dietary preferences-the 'livestock revolution' (Alexandratos and Bruinsma, 2012; Delgado et al., 1999; FAO, 2009). Dairy development provides economic opportunities for millions of poor smallholder farmers (Udo et al., 2011). Livestock is also associated with negative environmental impacts, including greenhouse gas (GHG) emissions, air pollution, high water consumption, loss of biodiversity and land degradation (de Vries and de Boer, 2010; Herrero et al., 2015; Steinfeld et al., 2006). Improved livestock feeding and forages have previously been highlighted as a triple-win strategy towards achieving climate-smart agriculture, increasing food security and resilience, and decreasing GHG intensities (Bryan et al., 2013; Peters et al., 2013; Thornton and Herrero, 2010). Tropical forages include a wide variety of sown or planted grasses, herbaceous or dual-purpose legumes and shrubs that are integrated into different agricultural systems to increase livestock productivity which is often constrained by quantity and quality feed (Rao et al., 2015). Livestock feeding and forages are thus at multiple crossroads: at a point where crucial decisions regarding future pathways are made, where productivity and environmental impacts meet, and where scientific disciplines including agronomy, soil and animal science intersect. However, knowledge on quantity and quality of feed gaps, and the potential impacts and trade-offs of improved livestock feeding practices on productivity, environment and livelihood dimensions across various crop-livestock systems in East Africa is limited and fragmented. 1.1.1 Mixed crop-livestock systems and dairy development in East Africa Global livestock systems can be distinguished as follows: a) pastoral and agro-pastoral with larger livestock herds, mainly composed of local breeds, which are grazed on public, private or communal land; b) intensive crop-livestock systems based on stall-feeding of 1-5 cross-bred or exotic cattle, forage cultivation and concentrate supplementation; c) semi-intensive mixed crop-livestock systems where animals split their time between enclosures and grazing and/or being tethered; d) others including forest-based, urban and landless systems. In pastoral and agro-pastoral systems, the main objective is meat production with milk as a by-product, whereas in intensive and semi-intensive mixed croplivestock systems dairy is often the focus (McDermott et al., 2010; Robinson et al., 2011; Seré and Steinfeld, 1996). Mixed crop-livestock systems, where crops and livestock are produced on the same farm, are widespread in developing countries. Two-thirds of the global population are engaged in these 22 Napier grass (Pennisetum...