The project objectives are:  

• to develop and demonstrate a robust system for the production of a new organic feed for laying hens based on the production of pathogenic free insect larvae cultivated in poultry manure. 
• to investigate the effect of larvae growth on the microbiology of the manure, including selected pathogens and human zoonotic bacteria to assess the microbiological safety to the system, 
• to investigate a prebiotic effect in the digestive system of poultry,
• to demonstrate that the integrated ON-farm system is ideal for treating animal manure through composting with larvae and thereby recycle energy, N and P,
• to investigate the effect of feeding on organic meat and eggs produced with the new feed composition through taste tests and laboratory tests,
• - and to demonstrate the high value of larvae digested manure as greenhouse and garden organic fertilizer product.

BioConVal at Insect Conference

On Thursday, 13 November 2014 the Danish Technological Institute and inSPIRe Innovation Community will host a conference on insects. This 1-day conference will focus on the current opportunities and barriers of insect production, and display their potential within various segments of the food and feed sectors.

One of the speakers will be Lotte Bjerrum who will present new research on the conversion of chicken manure by fly larvae.

2013: Progress and results

Fly larvae have an ideal amino acid composition; consequently, fly larvae could prove as an important source for organically produced essential amino acids, which enables egg producers to comply with the forthcoming EU requirement for 100% organic feed in  the production of organic egg. Moreover, a general improvement of poultry welfare is expected as the hens’ natural instinct for searching for food will become stimulated.

Fly larvae in manure can eliminate pathogenic and zoonotic bacteria

The veterinary aspects are investigated through research into how the larvae affect the amount of pathogenic bacteria in manure. Simultaneously, the risk of transferring infectious agents from manure to hens when feeding with live larvae is investigated. Tests show that the presence of fly larvae in manure can eliminate pathogenic and zoonotic bacteria such as E. coli, Salmonella and Campylobacter jejuni in the manure without being able to infect the larva or being transferred to the adult fly. Nevertheless, it appears that the use of larvae, either for direct use as live animal feed or as dried larvae meal, is against existing EU legislation (TSE regulation). However, the EU feed committee showed interest in the project, which resulted in an invitation to meet the committee during which the results from the microbiological tests were presented. The committee found the results very interesting and would like to look at how legislation can be changed. Nonetheless, the food safety aspect has to be further investigated.

Composting system for the production of fly larvae

The innovative part of the project is to develop and demonstrate an integrated and automated composting system for the production of fly larvae based on poultry manure at the individual poultry farm. In addition to the production of fly larvae, the biological treatment of manure from livestock will lead to an improved recirculation of N and P, partly as nutrients build up in the larvae and partly in improved utilisation of the compost. A prototype unit for composting 50 kg of manure per week has been developed. The composting tests on the prototype have generated concrete knowledge about larvae production. Two methods for separation of fly larvae from manure/ compost have been developed and characterised.  With the methods we are able to separate larvae with high efficiency, which is quite unique as this has been a technological challenge for decades. In addition, the conversion rate and speed have been increased through an optimisation of different cultivation parameters. A maximum conversion rate of 8% has been achieved, corresponding to 80 g of larvae per kg treated manure. The amount of poultry manure has increased from a few kg per week to more than 250 kg per week, by improving and streamlining the production of fly eggs, which i.a. comprises the development of oviposition-devices (collection of eggs) and techniques for storing eggs.   

The full-scale model

The experience from the prototypes has been used to design the full-scale model that was constructed by the Dutch manufacturer Dorset Green Machines. For some time, the full-scale model has been tested, and currently it is located at the organic, experimental host. Due to problems with controlling the larvae cultivation process in the full-scale model, 3 smaller composting units (each for 50 kg of manure) have been designed and they are now used to produce larvae for the ongoing feed experiment of organic layer hens. The hens are located in 6 pens divided into two control flocks and 2x2 experimental flocks that are given different amounts of larvae (5 and 15 g, respectively, per hen per day). Larvae cultivation takes place based on manure from the farm’s existing poultry production. The flocks are followed continually with respect to production data such as feed consumption, water consumption, mortality, egg weight and egg production as well as various welfare parameters. 

A combined feed and infection experiment

In addition to the ongoing feed experiment, a combined feed and infection experiment with pullets was carried out at the test facilities of Aarhus University in Foulum in spring 2013. During 8 weeks, 3 isoenergetic feed mixtures were compared with different protein sources: (i) fishmeal, (ii) fly larvae meal, (iii) fly larvae meal + fresh fly larvae. So far, most of the results have been treated statistically. In general, the result shows that fly larvae meal successfully can be used as protein source and as a replacement for fishmeal. Feeding with larvae meal to which live larvae have been added has resulted in increased growth and less feed consumption. In addition, the flocks that received living larvae showed less fear than the other flocks.

Considerable perspectives

In the course of the project, a lot of knowledge has been generated on the cultivation of fly larvae as a sustainable source for essential amino acids. In that way, fly larvae can contribute to meeting the nutritional challenge in organic egg production – especially when switching to 100% organic feeding. So far, the results show that the fly larva has a surprising ability to reduce the presence of pathogenic bacteria in manure. Investigations are being carried out concerning the effect on parasites, and in addition, eggs from the feed test will be investigated for dioxin. At the same time, the larvae-driven composting process is a very efficient way to reduce the amount of manure from the farm and will also result in the development of new organic compost products. 

The perspectives are considerable and reach far beyond what can be disclosed and tested in this project. Further work will make it possible to, e.g., look at other types of waste as cultivation media for the larvae, other larvae applications and efficient collection of the ammonia that still is discharged during the composting process. In connection with organic egg production, the perspectives are 100% organically fed and high welfare. In addition, some farmers will be able to reduce their costs for transportation of surplus manure as this initiative will reduce the amount of manure by app. 50%. 

Project leader

Lotte Bjerrum Friis-Holm
Teknologisk Institut 
Kongsvang Allé 29
DK-8000  Århus

Tel: (+45) 72 20 21 42

E-mail: lbfh@teknologisk.dk

 Find publications from the project in Organic Eprints