## 1 Introduction  
On a global scale, it has been estimated that 1.3 billion tons of food waste are disposed of in landfills, accounting for about a third of all food produced for human consumption annually [1; 2]. This not only causes significant loss to the global economy but also serious environmental problems as food waste contributes to greenhouse gas emissions, soil pollution, and odor production [2; 3; 4; 5]. Moreover, when food is wasted or lost, all costs involved in producing that food, including water, fertilizers, energy, and labor, are also wasted. It is estimated that the cropland area, fertilizer, and water exhausted to produce that amount of food that is wasted are approximately 198 million hectares, 28 million tons, and 173 billion cubic meters, respectively, each year on a global scale [6]. Meanwhile, food production to meet growing populations has faced challenges in many parts of the world in recent years due to adverse weather conditions such as drought, floods, and hurricanes [7; 8]. Thus, it is no surprise that priority has been given to the prevention of food waste and food loss by the Food and Agriculture Organization of the United Nations [9]. Increasing consumer demand for animal products has put immense pressure on the industry as animal production relies on scarce natural resources, including land and water, which may become more limited due to the negative impacts of global climate change [10; 11]. Increasing needs for animal products also induce a higher demand for feed ingredients--particularly cereal grains and protein meals--as these are the main energy and protein sources in pig and poultry diets [12; 13; 14]. The increasing price and/or limited availability of cereal grains and soybean meal in the regions where these feed ingredients are not produced locally have prompted the search for alternative feed ingredients for poultry production [9; 15]. Recycling food waste into poultry feed is a feasible solution that would help to address issues associated with food security, waste management, environmental challenges, and resource scarcity while alleviating competition for food between animals and humans [9; 16; 17]. Additionally, incorporating food waste into poultry feed may help to reduce feed cost and increase production efficiency, as feed cost accounts for 55 to 75% of the total production costs in poultry farming and the cost to manufacture recycled food waste is generally lower than conventional feed ingredients [18; 19]. Feeding animals with food scraps has been a common practice in many countries, particularly in the developing world [9]. This practice has several disadvantages, including nutrient variability, inconsistent waste supply, and risks associated with sanitary conditions and biological contaminants, such as live bacteria and viruses [20; 21; 22; 23]. However, with the application of modern processing technologies, it has been demonstrated that poultry feed may be formulated from food waste materials that meet the birds' nutritional requirements and hygiene and chemical safety standards [9; 22; 23; 24; 25]. Various countries, including Japan, South Korea, Taiwan, and the US, have already implemented the utilization of recycled food waste as animal feed [26]. In South Korea and Japan, it is estimated that approximately 46% and 40%, respectively, of mixed food waste is recycled as poultry and livestock feed, leading to considerable reductions in animal feed costs (40 to 60%) in these countries [27]. In the US, it has been reported that a significant amount of food waste (84-86.8%) is diverted to land applications or animal feed from the processing sector [28]. Currently, there are various facilities converting food waste from processing, manufacturing, and/or harvesting sectors into animal feed in the US [9]. However, food waste must be processed by applying a minimum temperature of 100 \({}^{\circ}\)C, boiling for a minimum duration of 30 min, or using other processing methods approved by the state governments before it can be incorporated into animal feed [29].