Housefly larvae: eco-friendly alternative to soy?

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Housefly larvae: eco-friendly alternative to soy?

Gepubliceerd op
21 juni 2016

The animal feed industry is looking for alternatives to environmentally harmful ingredients such as soybean meal and fishmeal. Hannah van Zanten researched the impact of housefly larvae as a food source and concluded that insects will primarily be interesting as animal feed if we become less dependent on fossil fuels.

“The fact that we are looking into insects as a protein-rich source of animal feed is logical,” says Hannah van Zanten, scientist at the Animal Production Systems chair group of Wageningen University. “Soy cultivation has had major negative effects such as deforestation, loss of biodiversity and high CO2 emissions, especially in Brazil and Argentina. Insects are considered an interesting alternative because they do not require much land and can feed on waste.”

Reduced CO2 emissions and land use

Van Zanten studied the environmental effects of the cultivation of housefly larvae for animal feed production in the Netherlands using data from an insect farm, two waste processing companies and an animal feed company that processes the larvae. Taking only the direct effects into account, the housefly larvae appear to be more eco-friendly per kilo than soy or fishmeal. “The production of larvae results in lower CO2 emissions than the production of soy and fishmeal, as well as reduced land use.”

Problem: waste

Van Zanten also analysed the indirect effects and these make the story much more nuanced. “In this study we fed the larvae partly with chicken manure and partly with waste. The waste is the problem as 98% is currently being fermented for generating bio-energy. This bio-energy replaces fossil fuels and so benefits the environment. Feeding all this waste to insects would increase the need for fossil fuels, resulting in a negative environmental balance overall.”

Model for calculating environmental effects

For her thesis Van Zanten developed a model to calculate the environmental consequences of using leftover products (e.g. waste) as livestock feed. “Based on this model we can calculate if changes such as using waste-fed insects are beneficial”. The research shows that it is currently unwise to aim at insect production for animal feed. This would be different if the Netherlands would become less reliant on fossil fuels in favour of wind and solar power, which would mean fermenting less waste for bio-energy. Remember that the industrial process for the production of larvae is becoming increasingly energy efficient, which also has a positive impact on the environment.”

Van Zanten advocates an integrated approach to achieve sustainable changes in the animal feed sector. “This study proves that a measure in one chain may have unexpected effects in another – positive or negative. One can only determine the environmental impact of a measure once all these effects have been determined.”

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