## 2 Literature
However, these studies have typically focused on large-scale commercial enterprises and overlooked small-scale family farms, likely due to their smaller contributions to economic growth. Small-scale farming in developing countries plays a key role in local food systems, often similar to that of agroecological food systems, which are more environmentally friendly than other types of production. The characteristics of agroecological food include the following: (1) minimizing the use of external resources; (2) recycling internal resources; (3) developing resilience to stress; (4) multipurposed; (5) integrated and incorporated into a more complex system; (6) contextualized; (7) more equitable; (8) nourishing [36]. However, [PERSON] and [PERSON] [37] suggested that the local food system could not be equated with sustainable food systems. Furthermore, since studies specifically focused on small chicken layer farms and their involvement in sustainable local food systems are rare, none were discovered as a result of our literature review parameters. Chicken layer farms in Thailand can be classified into three groups: (1) large-scale farms (2.8 percent), (2) contract farms (55.33 percent), and (3) independent small farms (41.87 percent) (less than 50,000 hens/farm) [38]. Records of farms from government statistics in 2020 indicated that there were 135,588 chicken layer farms in Thailand, with more than 57 million hens [34]. However, these statistics included all sizes of farms, ranging from one hen to millions. Thailand's Department of Husbandry reported a total of 2524 chicken layer farms in operation that had at least 1000 layers as of 2021, and among these, 51 farms were located in Nakhon Phanom Province. In 2019, Thailand produced 14.996 million eggs while domestic consumption was 14.728 million eggs (an average of 221 eggs/person/year) or 98.21 percent; the rest were exported [39]. Between 2014 and 2017, nearly 50 percent of domestic egg production was generated by eight agribusiness farms [40]. After the 2004 outbreak of avian influenza and several subsequent husbandry endemics, a closed-system chicken layer farm was proposed and adopted by many enterprises. Currently, the government promotes the closed-system design to prevent avian disease. Standards of practice for chicken layer farms were issued by the government to prevent diseases that can be transmitted to humans. The practice guidelines (for farms with 1000 or more hens) include the management of the following [41]: (1) farm components (e.g., farm location, farm design, etc. ), (2) feed, (3) water, (4) labor, (5) animal health, (6) avian welfare, (7) product, (8) environmental, and (9) database maintenance and records. Egg prices fluctuate considerably over time, as egg production is subject to a number of factors, including changes in temperature, poultry disease, raw materials in feed, and relevant world markets. Chicken layer farming requires substantial technological and capital investments, from animal breeding and feeds to animal medical care and maintenance. In 2018, the plummeting egg prices resulted in independent producers filing a complaint with Thailand's Department of Livestock Development, demanding that the State intervenes regarding market prices [42]. As Thailand is a member of the WTO (World Trade Organization), the state subsidiaries have been restricted; therefore, their egg production will continue to compete with international producers who can minimize their production costs. However, ongoing health concerns have resulted in import restrictions by a number of governments. Research into sustainable agricultural production has increased in recent decades [43; 44]. Thailand's National Research Council database on chicken egg research contains 62 published studies; however, none of them included \"environment\" or \"sustainable\" as the topics [45] and keywords. Most were concerned with improving efficiency in egg production to enhance competitiveness. Only a few studies focused on alternative feeds, particularly natural ingredients.