One billion people in Low- and Middle-Income Countries (LMICs) rely on livestock for their livelihoods, with livestock products providing crucial protein and micronutrients. The demand for livestock products is increasing due to urbanization and population growth, creating a challenge to enhance production and productivity. Currently, livestock productivity in LMICs is substantially lower than in high-income countries, leading to environmental concerns due to low yields and high greenhouse gas emissions. While access to high-quality feed is a primary constraint, despite decades of research and development efforts, the effectiveness of programs aimed at delivering high-quality feed to smallholder livestock keepers remains sparsely documented. This scoping review aims to assess the existing evidence on the uptake of improved livestock feed options, their impact on productivity, and their effects on smallholder farmer livelihoods, with the goal of identifying strategies to improve livestock feeding for enhanced productivity and farmer well-being. Feed improvement interventions reviewed include improved grasses and legumes, multipurpose trees, methods to increase the intake and nutritive value of crop residues, and methods for preserving fresh feed to bridge seasonal gaps. While these options have been widely researched and promoted, limited research addresses their adoption by farmers, effects on productivity, and ultimate impact on livelihoods.

The scoping review found an increasing trend in the documentation of feed intervention adoption processes over time, with a notable rise in adoption-focused literature complementing the earlier technical literature (feeding trials). Geographically, East Africa and Southeast Asia were the most represented regions, likely reflecting relevant development and research projects implemented in these areas. The review included a mix of quantitative, qualitative, and mixed-methods studies. The duration of the studies varied, with some spanning over 20 years, reflecting the time needed for interventions to impact livestock productivity and household livelihoods. Mixed livestock systems were more commonly covered than pastoral systems, reflecting the challenges of introducing new feed interventions in pastoral systems. The review observed a potential mismatch between research effort and the importance of different feed technologies. While crop residues are a major feed source, they received relatively little attention, possibly due to a lack of dedicated discipline and low visibility despite their ubiquity.

This scoping review followed the PRISMA-SCR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) checklist. A protocol was pre-registered. A comprehensive search strategy was employed across multiple bibliographic databases (CAB Abstracts, Web of Science, Scopus, Dissertations and Theses Global) and grey literature sources (over 20 sources). The search terms included variations of key concepts (feed improvement, small-scale producers, LMICs, adoption indicators). A machine learning process was used to identify relevant records. A three-step double-blind screening process was conducted (title, title and abstract, full text) by pairs of authors, with a third author as a tie-breaker. Inclusion criteria focused on studies of small-scale and agro-pastoral keepers of large and small ruminants, primary empirical research, and analysis of adoption, effects on productivity and/or livelihoods. Exclusion criteria included review articles, case studies, studies not focused on small-scale or agro-pastoral systems, studies not in specified languages (English, French, Spanish, or German) and studies not concerning ruminants. Data extraction involved a template with information about author, publication year, location, interventions, outcome measures, and key results. A quality assessment was conducted, using three criteria: quality of study methodology, justification of methodology, and overall subjective quality. Further analysis investigated adoption drivers and constraints by examining papers that explicitly addressed these factors.

From an initial 22,981 papers, only 73 met the inclusion criteria. Most studies focused solely on adoption (58 papers), fewer on productivity changes (19 papers), and some on livelihood changes (22 papers). Only 6 papers analyzed the complete pathway from adoption to productivity and livelihood impacts. Adoption rates for different feed interventions varied widely (forages: 0-90%; agroforestry: 8-87%; crop residues: 20-86%). Productivity changes also showed wide variation (7-61%). Livelihood impacts were more frequently reported than productivity changes, possibly due to easier measurement of indicators like income and diet. Household income changes ranged from 6 to 285%, gross margins from 58 to 519%, and labor changes from -24 to -70%. Analysis of 25 papers revealed several drivers of adoption, including farmer experience, expected productivity/income increase, access to extension and training, labor availability, market access, credit, and off-farm income. Constraints included labor requirements, low perceived net benefit, access to technology/inputs, technology complexity, and competition with other land uses. The quality of the included studies was deemed average to low, with many scoring low on methodology and justification.

The limited number of studies providing complete impact pathways highlights a major research gap. The bias towards technical aspects of feed supply without considering farmer adoption and context is a key issue. The wide ranges of impact indicators suggest several factors influencing results, including the diversity of interventions, different approaches to impact assessment, varying study time horizons, and the site-specificity of interventions. The lack of studies on crop residues, despite their importance, highlights the need for more research in this area. Adoption drivers and constraints identified can inform future strategies, emphasizing the need to consider technology complexity, perceived benefits, resource availability (land and labor), and market conditions. The success of feed interventions goes beyond biophysical suitability and involves social, economic, and knowledge domains.

This scoping review reveals a significant gap in evidence regarding the impact of improved livestock feed interventions on smallholder farmer livelihoods. Future research should prioritize studies that comprehensively assess the complete impact pathway, encompassing adoption, productivity changes, and livelihood improvements, particularly for under-researched feed types like crop residues. A holistic approach is crucial, considering farmer context, resource availability, and market dynamics. Development interventions should consider the knowledge-intensity of technologies and support capacity building alongside technology provision.

The review is limited by the available literature. The quality of included studies was variable. The wide range of contexts and methodologies made it challenging to draw strong comparative conclusions about the effectiveness of different feed interventions. The review's focus on published research might overlook valuable insights from grey literature or unpublished work.