Scale of the Piggery Farms
Half of the sampled farms (50%) were rearing 100 to 300 pigs while the total sample had an animal distribution of 10–5000 (Fig. 2). In terms of scale, most farms (62%) can be classified as large scale in line with swine farming classification in Sri Lanka (Table 2). Kothalawala et al. (2008)  reported that, in Sri Lanka, about 60% of the farms were small scale (< 50 animals), 25% were medium scale (51–100 animals), and 15% were large scales. According to this classification, 67% of the sample captured in this study represents large-scale farms, whereas 21% and 13% represent medium- and small-scale farms, respectively. Hence, the findings from this study are more applicable to large-scale farms.
Results revealed that in the interviewed sample, FW constitutes on average 82% of the total feed requirement. The proportion of FW to conventional feed may vary based on the purpose and the type of pigs raised on their farms,Footnote 2 the composition, and the quality of FW. Kothalawala et al. (2008)  reported, for example, that under large-scale swine farming in Sri Lanka, a mixed byproduct feeding system was more profitable compared to swill feeding or concentrate feeding.
Feed Sources and Collection
Feed supply was reportedly collected mostly from entities located in the CMC followed by the Kaduwela area. This could be attributed to the highest percentage of food service entities located in the commercial capital to cater to the large working force. About 26% of the farmers collected FW from hotels and restaurants only, while another 26% were mainly collecting from institutional canteens. However, a larger percentage (39%) collected the feed from multiple sources including hotels, hospitals, and institutional canteens to meet their demand. Around 42% of the farmers collected the FW from less than five collection points, while 38% collected from 5 to 10 collection points and 17% from more than 15 collection points daily. Informal communication networks for sourcing FW were reported by 62% of farmers.
The average amount of FW collected per day by piggery farmers varied with factors such as the size of the piggery and the availability of feed. The survey indicated a significant variation between 50 and 10,000 kg of feed collection among the farmers with the majority (75%) collecting less than 1,000 kg of FW per day (Fig. 3). In terms of composition, the majority (70% of the farmers) collected FW in the form of a mix of many food commodities while 30% mainly collected rice and cooked FW.
Operational Aspects: Transport and Cost
It was noted that 96% of the pig farmers collected fresh feed daily. Farmers travel on average 38 km back and forth to collect the feed. This is because the piggeries are mostly located in the peri-urban areas in the Colombo, Gampaha, and Kalutara districts and the feed supply comes mostly from the larger business entities located in urban Colombo. Although the distance appears to be considerable, it implies that the value of (low cost) FW as a feed has been well recognized by the farmers. However, given the bias of the sample to larger farms, it should not be concluded that also smaller farms can afford the transport.
Minimizing the number of collection points while maximizing the collected FW volumes per point is important from a transport cost perspective, and to keep the FW as fresh as possible. In an ideal scenario, just one major supplier would fill the truck. Although there are many sectors which provide a high percentage of FW, of which 46–70% is at the moment of disposal still edible for humans (Table 3), the largest overall share derives from households but with the smallest volume per collection point. In these cases, it would help farmers to access possible solid waste transfer stations, compost plants, or landfills with separate organic waste processing.
The use of FW as feed lowers pig production costs due to the low cost of FW compared to conventional feeds. It was reported in the European Union (EU) that feed costs ranged from 55 to 72% of total pig production costs . Research conducted in Bihar, India, shows that the feed cost was up to 72 to 80% of the total cost . According to data available, the practice of utilizing FW as feed by Sri Lankan pig farmers is a rational decision, given that feed cost accounted for about 68% of the total cost of production of pork . On the other hand, this is a win–win situation also for the food service sector as the waste is diverted reliably, daily, and at no cost.
While most farmers received the feed supply free of charge, 26% of the farmers paid a price ranging from LKR 2–40/kg with more than 50% paying LKR 10/kg when the waste was supplied through intermediaries.Footnote 3 This practice was also reported from the neighboring Negombo Municipal Council where approximately 1 to 2 tonnes of FW was collected by private traders to sell as animal feed for piggery farmers . FW generated in Kandy and Peradeniya Teaching Hospitals located in the Central Province of the country was also sold to piggeries . This indicates the possibility of creating business opportunities for private sector engagement that can consequently expand the sector to create more revenue and jobs. In countries such as Japan and South Korea, businesses have been established to collect and process FW and sell it to farmers .
FW for Animal feed? Current Challenges
Given that the pig farmers mostly receive FW free of charge, they use it as the major feed source instead of commercial concentrated feed. However, the seasonal nature of the supply of FW linked with tourism and festive seasons and inadequate supply of feed under the Covid-19 pandemic (and lockdown of restaurants) are key challenges. Feed shortage under Covid-19 resulted in increased cost of operations for sourcing commercial feed. Farmers indicated a 50–60% income loss due to the unavailability of the FW during the peak of the pandemic.
A more technical challenge related to FW is that it must be fully segregated from other waste to avoid nonfood materials such as plastic, polythene, or glass, entering the feed. It is important to collect FW separately from other waste and in a sufficiently fresh condition as it is being practiced in several SE Asian countries. In South Korea and Taiwan, for example, FW can constitute 81 and 72% of animal feed, respectively . According to the current legislation of SW management in Sri Lanka, source segregation is expected from a policy perspective, but its enforcement remains a challenge, and especially at the household level non-satisfactory . Separating organic and inorganic parts at farm would result in additional [labor] costs for pig farmers in case they start targeting FW collected from households.
FW may also potentially pose a biosafety risk, as meat residuals can transmit Food and Mouth Disease (FMD) and African swine fever unless the waste is processed . For example, in the EU, the use of catering waste in animal feed was prohibited in 2002 after the FMD outbreak that took place in 2001, due to the feeding of uncooked FW to swine [38, 43, 44]. Utilization of FW as animal feed essentially requires adequate pre-treatment and adherence to a clear guideline for storage and way of feeding. Proper heat treatment would be sufficient to inactivate harmful pathogens and the safety for treated FW has been demonstrated in many studies [15, 44]. In countries such as Japan and South Korea where FW is commonly used as animal feed, the usage has been closely regulated through legislation to ensure proper heat treatment, appropriate storage, and transport of FW . Countries such as Malaysia have introduced policy instruments as a control measure to tackle such challenges; for example, the Feed Act (Act 698) (45) stipulates that not all FW is suitable for use as animal feed for livestock except for the more common practice of harvesting of carcass bones and eggshells .
Although safety and hygiene of the feed have been a concern at the farmers’ end from the business perspective and at the authorities’ end from a health perspective, currently no national regulations are guiding the safe use of FW as animal feed in Sri Lanka, while there are many technical options . Despite this lack of regulations, most of the farmers (88%) stated that they boil the collected FW (containing raw meat, fish, or poultry waste) before feeding it to their animals, but not already cooked dishes. Answers varied, however, e.g., in view of the boiling duration (45 min to 4–5 h), or the guidance farmers use, with most farmers confirming the lack of any.
Foot and mouth disease is common in Sri Lanka, although so far mostly in cattle and buffaloes. It usually coincides with the seasonal movement of livestock returning to the villages as a part of extensive and uncontrolled livestock management practice in Sri Lanka’s dry zone. Swine were affected by the Porcine Reproductive and Respiratory Syndrome (PRRS) with over 200 deaths in 2020, mostly in the Central and North Central provinces. Feeding of untreated swill and poor or no biosecurity practices in swine farms were named as the main sources of the virus .
Potential of FW as Animal Feed
Based on the data gathered during the survey, it was calculated that in total, 34 tonnes of FW from the Colombo area were absorbed daily by the surveyed piggeries. However, the amount collected by the farmers varied between 50 and 10,000 kg/day depending on demand and supply, with 75% of farmers collecting less than 1,000 kg/day. On average, large-scale farmers collect about 2,060 kg/day, whereas medium-scale and small-scale farmers collect about 255 kg/day and 60 kg/day, respectively. Swill feed per pig per day was estimated to be on average 3.4 kg/day.
According to the 2019 database from the Department of Animal Production and Health, Sri Lanka, there are 503 registered pig farmsFootnote 4 in the Western Province with 53,225 animals . If all the pig farmers would (e.g., for financial reasons) favor FW as feed, the sector could absorb as much as 181 tonnes FW per day, which is about 20% of what the authorities collect and with few exceptions dump in landfills [10, 42]. Although these estimates need to be verified, given the sampling bias to larger farms, the high number of piggeries within the Western Province shows the potential of the sector to reduce the FW volume and contribute to the circular economy, while helping to reduce the carbon footprint of the swine sector through reduced commercial feed production/use, and avoided GHG emission from landfills .