Integrating camel production systems into circular bioeconomy frameworks in arid and semi-arid regions: a narrative review of feed resources, waste valorization, and sustainability.

Camels, the one-humped Camelus dromedarius and the two-humped Camelus bactrianus, are uniquely adapted livestock species to the arid and semi-arid regions. Their distinctive behavioral and physiological adaptations enable them to maintain productivity in these challenging ecosystems, characterized by prolonged heat stress, limited feed resources, and water scarcity. Despite these advantages and their vital role in rural livelihoods, food security and the resilience of dryland ecosystems, the potential contribution of camel production systems to the circular bioeconomy has not been comprehensively synthesized. This review examines how camel production can contribute to circular bioeconomy priciples through (i) the efficient utilization and valorization of scarce feed resources in drylands, particularly crop residues and fibrous agro-industrial by-products (ii) the valorization of manure, processing residues, and other coproducts (iii) value-addition and diversification of camel-derived products, (iv) the environmental, economic, and social sustainability of camel production system, and (v) the identification of key research gaps, and priorities for future research. Relevant literature was identified from major scientific databases, including Scopus, Web of Science, and Google Scholar, using combination of keywords related to camel production, circular bioeconomy, resource utilization, waste valorization, and sustainability, with evidence drawn from North Africa, the Middle East, the Horn of Africa, the Sahel, Australia, and Central Asia. The golobal camel population is estimated to be 42 million heads, with more than 80% concentrated in Africa, where they efficiently utilize halophytic vegetation, browse species, crop residues, and agro-industrial by-products that are unsuitable for human consumption, thereby enhancing resource-use efficiency and contributing to the sustainability of circular production systems. Similarly, camel manure and processing residues can be transformed into valuable bio-based products that may enhance resource efficiency and reduce waste generation in circular production systems. The economic viability and long-term sustainability of camel production systems may be significantly improved by value-added processing of camel-derived products, such as meat, milk, hides, fiber, and other coproducts, thereby promoting income diversification. Sustainability considerations include resource efficiency, waste reduction, economic returns, livelihood resilience, and environmental impacts, although quantitative life-cycle evidence remains limited. Furthermore, appropriate herd management, disease prevention, supportive institutional frameworks, and well-developed marketing channels could enhance the environmental and socioeconomic sustainability of camel production systems. Nevertheless, challenges including long reproductive intervals, relatively low productivity, diseases, and limited life-cycle assessment data, incomplete nutritional information, and limited economic evaluation of circular interventions continue to hinder the wider adoption of camel-based circular bioeconomy approaches. This review provides a comprehensive synthesis of current knowledge and identify key research priorities for developing resource-efficient and climate-resilient camel production systems in arid and semi-arid regions.