Development and Evaluation of Vegetable and Fish Wastes Silage (VFWS) Additive to Nile Tilapia (Oreochromis niloticus) Feeds

Fish, particularly tilapia, is a staple food in Filipino cuisine. It is the primary source of dietary protein, vitamins, micronutrients, and minerals (Pandey and Upadhyay, 2022). Not only do they provide essential proteins but are also a valuable commodity traded worldwide and serve as a means of income for fish-producing countries, including the Philippines. Besides producing a large quantity of fish, aquaculture operations also help alleviate food insecurity, a major issue among the country'spoorest regions and agricultural households.

A record of 214 MTwas produced globally in fisheries and aquaculture in 2020, including 178 MT offish and 36 MT of algae (SOFIA, 2022). This growth largely accounts for the advancement of aquaculture within Asia. Much of aquaculture'ssuccess depends on feed quality and availability. Good quality feed, however, tends to be more expensive, partly because some feed ingredients used are imported, which increases production costs whether it is for poultry, swine, or aquaculture. Around 60-70% of the entire cost of operating a fish farm is spent on feed (Mukta, Khan, Mian & Juice, 2019). One way to reduce feed costs in fish farming is by utilizing alternative feed ingredients. These can include waste materials that are readily available. Fish waste and vegetable wastes, in particular, have the potential to be used as raw material for producing feed additives, thereby decreasing reliance on imported feed ingredients. Likewise, the aquaculture industry’sgrowth is often accompanied by a significant volume of waste, if not properly managed it can lead to environmental pollution and loss of biodiversity. Fish waste is generated in large quantities from processing plants and wet markets. The average daily production offish waste in Philippine wet markets was found to be 70.3 kg, with no significant differences across locations (De Ungria et al., 2023). However, vegetable wastes, on the other hand, account for 40 to 50% of postharvest losses of fruits and vegetables and 42% of its vegetable production losses was due to spoiling, resulting in landfill problems (Sanchez et al., 2019). Despite this, the vegetable waste is a rich source of nutrients. It contains between 2.11% and 2.71% protein, 1.08% fat, and 14-15% fiber. It also has a high-water content, ranging from 89% to 90% which is a good source of calcium and other minerals (Andriani & Pratama, 2022).

Somehow, these kinds of waste materials can be processed and further enhanced through fermentation. This process increases the bioavailability of nutrients, improves the palatability of the feed. Fermenting vegetable and fish waste is expected to improve the quality of feed additives, increase digestibility, and develop flavors and aromas suitable for fish (Adriani, Lili, Zidni, Wiyatna, & Risiana., 2020). Feed additives are substances added to animal feed to enhance its nutritional value, improve the animal health and productivity, or make the feed more appealing (Olagunju et al., 2023). Nutrition is known to have a considerable effect on the reproductive performance and gonadal development offish (Gioacchini, Olivotto, Ashouri, & Carnevali., 2023). The addition of feed additives was found to improve growth but the nutritional impact of reducing the protein digestibility and amino acid balance in this feed heavily affected the overall performance, particularly feed conversion ratio (FCR) and survival rate (Towers, 2015).

Including this fermented vegetable and fish waste silage into tilapia feeds provides for a more sustainable and profitable aquaculture sector. This aligns with the principles of circular economy, which minimizes waste and reuses resources. Some studies have explored the use of single waste materials, but the combination of assorted vegetable leftovers and fish viscera waste and its optimal inclusion levels as supplementary fish feed additives has not yet been thoroughly investigated. Finding ways for sustainable feed production is essential particularly cost saving strategies considering the unabated increase of the price of commercial aqua diets. Therefore, the utilization of vegetable and fish viscera wastes when processed by fermentation procedures to make it safe and palatable for inclusion to commercial aqua diets is very timely. Finally, these nutritional strategies can further mitigate the adverse effect of climate change at the same time addressing economic problems of the fisherfolks in the country.

Fermentation improves the nutritional content and may also positively influence fish growth, health, and overall production efficiency. This study developed a sustainable, cost-effective, and environmentally responsible feed additive using fermented dietary vegetable-fish waste silage additive into Nile tilapia feeds. Additionally, incorporating waste products aligns with circular economy principles and sustainable aquaculture. The findings could benefit the fisherfolks, as it enhanced their understanding of alternative feed sources and their practical applications to improve the nutritional quality and palatability of the feed, resulting in better growth, feed conversion ratio, making fish farming more efficient and reduced overall feed costs. The study focused on developing and analyzing the nutritional composition of fermented dietary vegetable and fish waste silage (VFWS) as a potential feed additive for Nile tilapia. It evaluated the effectiveness of silage-based feeds on the growth performance, feed conversion ratios and weight gain. Additionally, the study examined the economic benefits of using VFWS compared to traditional feed additives. However the study was limited to a specific period, which might have restricted the understanding of long-term effects of silage-based feeds on Nile tilapia. Some of the parameters, such water quality parameters were not analyzed due to the limitation of resources, time, and situation.