Sustainability: Larva production for the benefit of man, animal and environment

This is the third in a series of articles about sustainability and specifically sustainability within the University. What are our staff members contributing in their fields of expertise; in which sustainable projects and initiatives are they involved and what contribution do they make to this important issue in the rest of South Africa?

First article: Sustainability is all about the future – Prof Russel Botman

Second article: Sustainability: Rio+20 – The Stellenbosch Connection

The types of flies (breeding parents) in the project produce eggs in special cages in a fly shed. Female black soldier flies lay their eggs on plastic strips while female house flies lay their eggs in special tubs containing a bait mixture which consists of among others milk and sugar.

Larva production for the benefit of man, animal and environment

The principle of sustainability lies at the heart of a research project for the mass-rearing of fly and blowfly larvae into animal feed. In addition to the excellent protein source created, this production also holds many other benefits for people, animals and the environment, says Dr Elsje Pieterse, lecturer in Monogastric Nutrition at the Department of Animal Sciences at the Stellenbosch University (SU). She tells more about this research project at the SU’s Mariendahl experimental farm.

What is the sustainable protein project that you are involved in all about?

I am involved in a project for the mass-rearing of fly and blowfly larvae in collaboration with AgriProtein, a Cape Town-based animal feed company. It is an excellent alternative to fishmeal, an important ingredient of animal feed which is becoming increasingly more expensive and scarce since this protein source is being overutilised.

We use various types of waste, such as food with an expired shelf life, fruit pulp and waste, food leftovers from hotels and hostels and also meat waste from abattoirs, and then identify various insects fit to break down this waste. We then feed the larvae of those insects from the specific waste stream. The larvae are then dried, minced to larva meal and mixed with animal feed.

The larva meal is a good protein source for animals – the feed we have tested thus far produced the same and even better results as fishmeal and always better results as soy. It is therefore a replacement of the total protein required by animals, and on top of it the food they had eaten initially. Free-range chicken eat worms and larvae. This then brings us back to the original feed animals had eaten.

The waste that is used, would otherwise have landed up in landfill sites where it would have decayed with pathogenic organisms and nutrients landing up in the soil and ground water. Such areas become uncontrolled breeding places for flies that might carry diseases.

This project is the answer to this problem, since it keeps such organic products away from landfill sites and converts it into valuable, controlled breeding areas for insects. Consequently safe animal protein and valuable byproducts – among others oil, chitin (the insect’s exoskeleton) and enzymes – can be harvested.

The eggs are harvested in the morning. Each female black soldier fly lays 350 to 700 eggs, while a female house fly lays 500 to 600. The eggs then go into a hatchery where they hatch and the larvae start eating.

In addition to animal feed, what other benefits does this project hold?

Many of the byproducts are currently being investigated for biomedical uses, such as enzymes from blowfly larvae which are used for the treatment of diabetic sores, while the chitin of pupae looks promising in the treatment of high cholesterol, but without the detrimental effect on the patient that some current treaments hold.

Enzymes may also be valuable for breaking down cellulose, and chitin can be used for the manufacturing of biodegradable plastic. Oil rendered from larvae has the ideal fatty acid composition for use in biodiesel production – in contrast with that which is used currently and which competes with vegetable oils for human consumption.

During the process where larvae are used to break down waste. All the organic waste eaten – an astonishing amount – is converted into natural compost. The liquid part is used to replace urea fertiliser while the remaining part is used as soil conditioner, adding organic material to the soil.

What is the impact of this research on a sustainable future?

This entire project is based on the principle of sustainability. It promotes the maintenance of our water quality since we take waste from the system and prevent contamination of ground water and surface water. In addition to this, nutrients are harvested from a potential risk source but the nutrients are not a risk – it does not hold pathogens and toxins.

The product is therefore a very good protein source for animals, while the byproducts can be used in various fields.The possibility of harvesting enzymes on a massive scale is being investigated, especially seeing that Africa is struggling to cope with diabetes and the medicine for its treatment being so expensive.Since specific enzymes are harvested, it can be used to treat diabetic wounds and avoid operations. This will enhance people’s quality of life.

These insects also possess anti-tumour, anti-bacterial, anti-inflammatory and anti-oxidative  characteristics. Danish researchers are specifically interested in this. We suspect it will also be strengthening the immune system of animals feeding on this. Animals will consequently not become ill and therefore not have to use medicine.

As far as biochemical sustainability is concerned, filters made from chitin can be used to remove heavy metals from water systems. Chitin is used to harvest uranium on the ocean bed to be made available for nuclear reactors. We are therefore returning to nature’s original intention and rediscovering that which had initially been bred in nature. Because we can recycle our nutrients, we do not have to wait until it becomes ammonia and then return via the system to plants, and then to animals. We can harvest it before it enters the atmosphere, and the processes produce no methane.

And as long as there are people who eat, there will be waste and therefore a source from which to make protein and other byproducts. This is the highest form of sustainability because one recycles. Whether you do it on a small scale in your backyard by feeding your vegetable peels and food waste to larvae which in turn are eaten by birds,or whether you do it on a large scale by feeding farm animals – the value added to the environment is phenomenal.

The larvae are put into special troughs full of organic waste where they grow within 72 hours to such an extent that they can be harvested at an average length of 15 mm.

Who is involved in the project?

I represent the SU, while AgriProtein has engineers, entomologists, a production manager and ten junior staff members on the project. We operate in collaboration with the London School of Hygiene and Tropical Diseases and also work closely with the University of Alecante.  We have been involved with the project since 2007. Research groups overseas are showing wide interest in our activities and the project has also attracted quite a lot of media interest. Mariendahl is used for broadcasts by various local and overseas radio and television teams from inter alia Germany, America and England. On the local front recordings have been made for Carte Blanche and just recently also for 50/50, which will be broadcast on 4 March.

What are the plans for the future?
The initial research has been completed and the process can now be commercialised. New projects are started with communities in the area as well as in the Langkloof which will add value to the socioeconomic welfare of these communities. AgriProtein intends erecting a commercial plant in the Western Cape.

We want to recycle fruit waste in the Langkloof. All the fruit that are not processed into juice or packed, land up in a production unit for the production of larvae. The larvae will be returned in the form of free-range chickens, and egg and pork production. Season workers are suffering because the fruit industry is seasonal, so this will also provide them with more sustainability. Many other waste streams, for instance waste from dairies, have also been identified.

We are also busy with a project which entails investigating the ability of these insects to break down human pit toilet waste, as well as pig, chicken and horse manure. For many years we have tried killing insects, instead of nurturing them. We completely misunderstood them – they have a special ability to break down our waste and take the nutrients from that before it can become detrimental to the environment.