Efficiency and Sustainability of Alternative Protein Sources for Livestock Production in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Sub-Saharan Africa (SSA) faces growing challenges in sustainable livestock production due to high costs and limited availability of conventional protein sources such as soybean meal and fishmeal. This systematic review and meta-analysis evaluated the nutritional efficiency and sustainability of locally available alternative protein sources for livestock feed in SSA. Following PRISMA guidelines, systematic searches were conducted across five databases (PubMed, Web of Science, ScienceDirect, Scopus, Google Scholar) for peer-reviewed studies published between 2010 and 2024. Eligible studies examined nutritional efficiency or environmental sustainability outcomes of non-traditional protein sources in livestock production within SSA. Meta-analyses were performed for comparable quantitative outcomes including crude protein content, average daily gain (ADG), and feed conversion ratio (FCR). From 3,826 identified records, 68 studies met inclusion criteria. The most frequently studied protein alternatives were insect meals, leguminous plants, and agricultural byproducts. Meta-analysis revealed that black soldier fly (Hermetia illucens) meal significantly improved ADG by 18% (95% CI: 12–24%, p < 0.01) compared to conventional feeds, with mean crude protein content of 45.7 ± 3.2%. Legume-based proteins and oilseed processing byproducts demonstrated moderate digestibility (70–82%) and cost advantages but exhibited variable amino acid profiles. Algae-based and food waste-derived proteins showed superior sustainability ratings (reduced land use, lower greenhouse gas emissions) but were underrepresented in the literature. Substantial heterogeneity existed across studies (I² = 68–85%) due to species variation, production systems, and methodological differences. These findings demonstrate that alternative protein sources hold promise for enhancing livestock productivity and environmental sustainability in SSA. However, research distribution is geographically uneven, with limited studies on cattle and small ruminants. Policy support, value chain development, and region-specific validation trials are essential to scale these innovations and reduce dependence on imported conventional feeds.