The Use of Pig Manure as Feed for BSFL
By Bob Holtermans & Bina Roovers, Insect Engineers
Testing the Potential: BSF Larvae on Pig Manure as Feedstock
The global demand for sustainable food and animal feed is growing rapidly, placing significant pressure on natural resources and conventional agricultural systems.
Innovative solutions are necessary to reduce environmental impact while maintaining productivity. Among these solutions, the use of BSF larvae to process organic waste streams has emerged as a promising approach. BSF larvae efficiently convert organic residues into high-quality insect biomass, rich in proteins and fats, while simultaneously producing a nutrient-dense organic fertilizer known as frass.
This technology aligns with the principles of a bio-based circular economy, where organic waste streams are recycled into valuable resources, closing nutrient cycles and contributing to more sustainable agriculture. While the concept is promising, regulatory constraints currently restrict the use of BSF larvae grown on animal manure as animal feed within the European Union. Nonetheless, steps are taken to reconsider and potentially relax these regulations, reflecting the growing interest in insect-based feed alternatives.
In December 2024, Insect Engineers conducted a controlled experiment to assess the suitability of pig manure as a feed source for BSF larvae. The Görtz Group supplied the pig manure, FreezeM supplied the larvae. Additionally, Nijsen Company provided the BSF Feed. The study aimed to evaluate larval growth, feed conversion efficiency, and the potential for scaling up manure processing using BSF larvae.
Why Use BSF Larvae for Manure Processing?
BSF larvae, are recognized as effective agents for manure management and organic waste upcycling.
Incorporating BSF larvae into manure processing systems offers advantages:
- Nutrient Recycling: BSF larvae convert manure into high-quality biomass that can serve as a protein- and fat-rich feed for animals, providing an alternative to conventional feed sources such as soy or fishmeal.
- Reduction of Environmental Pressure: Larval digestion reduces ammonia and greenhouse gas emissions commonly associated with manure storage and treatment.
- Alternative to Traditional Manure Management: Conventional technologies such as composting or anaerobic digestion often require high capital investment and maintenance and may face social acceptance barriers. BSF-based processing offers a low-cost, scalable alternative.
- Potential for Bioenergy: Larval fats can be extracted and utilized for biodiesel or other bioenergy applications.
- Mitigation of Environmental Pollution: In intensive livestock regions, manure surpluses can contribute to soil and water pollution. BSF larvae offer a practical solution to mitigate these risks while generating economic value.
Research Setup and Materials
Before scaling up BSF larvae processing, a small-scale experiment was conducted to determine the optimal feed composition for larval growth, feed conversion, and digestion efficiency. Three different feed mixtures were evaluated in 60 × 40 cm crates, each containing 12 kg of feed and 12,000 larvae. The feed components included wet pig manure (99% moisture), dried pig manure (7% moisture), and BSF feed (10% moisture).
The main objective was to assess how moisture content and feed composition affected larval survival, growth rate, and conversion efficiency.
Small-Scale Test Results
The results highlighted the critical role of moisture content. Larvae could not process feed with moisture above 70% and often attempted to escape, while moisture below 65% reduced growth and conversion. Additionally, the larvae effectively eliminated the strong odour of pig manure, demonstrating environmental benefits. Larval growth was significantly improved when BSF feed was added, underscoring the importance of supplementing manure with digestible nutrients.
Large-Scale Test
Building on these findings, a large-scale test was conducted using a 12-meter ZOEM bed, where 1,200,000 larvae were introduced to 666 kg of feed composed of 60% wet pig manure, 30% BSF feed, and 10% dried pig manure. The mixture was slightly drier than in the crate trials, facilitated by the larger surface area and controlled climate conditions.
Large-Scale Test Results
After nine days, the feed was fully digested, mirroring the small-scale results. Approximately 41 kg of larvae were harvested, calculated by weighing a sample of 50 larvae and scaling to the full population. Additionally, 150 kg of nutrient-rich frass was produced, measured using twelve 25-liter containers each weighing 12.5 kg. The larval conversion ratio was 22.5%, indicating that nearly a quarter of the feed mass was converted into insect biomass. Beyond biomass production, the larvae effectively reduced odour and the volume of the pig manure, demonstrating the potential for improved waste management and environmental benefits.
Financial Analysis
Economic feasibility is a critical consideration for scaling BSF-based manure processing. To achieve economic viability, the system would need to process approximately 50 tons of wet feed per day (Table 1).
Profitability depends on multiple factors, including:
- Selling price of live or dried larvae
- Production capacity and labour costs
- Savings on manure disposal fees
10.000kg BSF feed
The analysis demonstrates that BSF-based manure processing can be cost-competitive, particularly when integrated with existing livestock operations that generate surplus manure.
Discussion and Implications
The research by Insect Engineers demonstrates that pig manure can be effectively used as feed for BSF larvae, providing practical insights.
Maintaining feed moisture between 65% and 70% was critical for maximizing larval growth and preventing escape, while supplementing manure with digestible BSF feed significantly improved larval biomass and conversion efficiency.
Larval processing also offered environmental benefits, reducing odour and stabilizing the manure, which contributes to improved hygiene and a lower environmental footprint.
Economically, scaling the process appears feasible, with savings on manure disposal and potential revenue from larvae as animal feed or biofuel feedstock.
However, regulatory constraints currently prevent the commercial sale of larvae reared on animal manure as feed within the EU. Overcoming these legal hurdles could unlock substantial economic and environmental advantages, positioning BSF larvae as a sustainable and practical solution for organic waste management in agriculture.
Conclusion
The study by Insect Engineers provides compelling evidence that BSF larvae can efficiently process pig manure, produce valuable insect biomass and frass while reduce environmental impacts. The research highlights the importance of moisture management, feed supplementation, and scaling considerations for optimizing larval growth and feed conversion.
BSF-based manure processing represents a practical, sustainable, and economically viable approach to closing nutrient loops in livestock production systems. With regulatory adjustments, this technology could become a cornerstone of circular agriculture, reducing dependence on conventional feed sources, mitigating environmental pollution, and generating new revenue streams for farmers.
Enjoyed reading this article? You can read the full issue of our Beta Buzz #6: From Waste To Value publication here
