SummaryMost aspects connected with the recycling of animal waste as animal feedstuff are reviewed, with particular emphasis on the ensilage of poultry waste.Financial incentives and changes in agriculture and people's habits are examined as reasons for recent interest in utilisation/recycling processes. Identification of products and markets; assured future supplies of particular wastes; minimisation of energy requirements; absence of hazards and the value of the final product are proposed as the main principles involved. The various types of agricultural waste are summarised.Physico/chemical and biological treatment, as well as the use of the biological intermediates are examined in detail as the main recycling methods with feedstuff's and fertilisers as the chief endproducts.Though many workers have given thought to the health aspects of recycling, particularly the presence and effects of chemical residues, and the transmission of pathogens and parasites; a review of the published work indicates a need for more research in this field. The details and impact of the UK Government's Protein Processing Order is discussed.Recycling of poultry manure and litter is of particular interest as these materials contain high amounts of digestible proteins suitable for ruminants. With drying becoming uneconomic due to high energy costs and environmental pollution, ensilage methods have been examined in more detail. Work in the US using maize forage or grain as an additive and a moisture content of about 40% has led to the development of commercially viable systems. Research effort in the UK has been primarily concerned with satisfying the proposed Protein Processing Order and a number of materials and ensilage conditions examined. The efficiency of the process was determined by examining the presence/absence or changes in Salmonella, Clostridium, Lactobacillus, E. coli, coliform and mould populations; as well as measuring pH and temperature changes and analysing for nutritive values.Ensilage of broiler litter as 30, 40, 50 and 65% moisture content, with the addition of 0, 1, 3, 5, 10, 12, 15, 20% molasses in combination with 0, 2, formic 4% acid or propionic acid for periods of 6–10 weeks was examined experimentally in laboratory scale trials. It appears from the results to date that an acceptable and commercially viable system can be developed.Results are also reported of a field trial using a “Silopress” technique, the resultant litter silage being fed successfully to bullocks with no apparent ill effects.