Can insect protein replace soya beans in pig diets?

Soya bean is often cited as one of the key contributors of greenhouse gas emissions (GHGs) from pig farms.

With all livestock sectors now facing moral- and government-driven pressures to reduce their GHGs, many producers are now looking to move away from soya beans and replace them with lower-emission sources of protein.

To date, alternatives have been limited. However, there is a strong belief that protein from insects could now help fill that gap.

This was highlighted at the Insects as Food and Feed Conference (26-27 April 2022), hosted by the Royal Society of Entomology (RES).

So, what are the prospects, the opportunities, and the potential barriers for insect protein in pig diets?

See also: How a layer producer is cutting carbon footprint with maggots

Prospects

Arnold van Huis from Wageningen University and Research in the Netherlands recently published an entomological research paper looking into the challenges and prospects for edible insects.

He says most insect production is targeted towards the pet food industry. However, growth is expected for use in pig (and poultry) feed over the coming years.

While a few species can be used as a protein source, the one looking most promising for feed markets is the black soldier fly.

Globally, this insect can be fed as an adult fly protein meal, or as larvae.

Prof van Huis says soya bean meal accounts for about 85% of the protein supplements fed to pigs, and the black soldier fly has the potential to partially replace this.

Black soldier fly larvae can be reared on a wide range of cheap feed sources and substrates – including food waste – and require much less space to grow than more traditional protein sources.

Slaughterhouse products, manure, catering waste and supermarket products containing meat or fish cannot be used when rearing insects for animal feed, as laid out in food hygiene legislation.

Opportunities

Developments in insect genetics, improved animal health as a result of feeding on insect protein, and the potential to use insect by-products – such as frass, the waste from insect larvae – in wider agriculture are among potential opportunities.

Insect production

Breeding insects suited to commercial production is a key focus for Desmond Cave of genetics firm Beta Bugs, based at the Roslin Innovation Centre in Scotland.

He has been working on the development of the black soldier fly for the past two-and-a-half years.

While the black soldier fly has been farmed commercially for some time, Mr Cave says the genetic improvement to allow large-scale production has not always been sufficient.

“We’re concentrating on improving this by selectively breeding the black soldier fly. Our larvae are heavier than the standard fly, and grow more quickly, and the adult flies produce more eggs.”

One gram of eggs from a standard fly, grown over a year, could produce about 104kg of larvae.

In comparison, a gram of genetically improved eggs could produce in the region of 226kg of larvae a year.

Beta Bugs is also aiming to improve mass, development time, hatch rate and the number of eggs laid by the adult fly, he adds.

Pig health

Various studies have shown beneficial health effects when animals are fed black soldier fly and/or its larvae, explains Prof van Huis. They include:

• Less diarrhoea, better immune response and improved small intestinal morphology – which is linked with good gut health (Choi et al, 2020)
• An antimicrobial effect on gram positive bacteria due to the lauric acid found in black soldier flies (Spranghers et al, 2018)
• Similar amino acid digestibility and growth compared with soya and fish meal (Veldkamp and Vernooij, 2021)
• Reduced tail biting when fed live black soldier fly larvae (Ipema et al, 2021)

Further research has shown feeding black soldier fly larvae can also potentially reduce ammonia pollution from livestock manure, he adds.

Barriers

Legislation and cost were the two biggest barriers highlighted at the conference.

Under EU legislation, insect processed animal proteins (PAPs), including the black soldier fly, have been allowed in pig (and poultry) feed since 2021.

This is not yet the case for UK farmers, explains Rachel O’Connor, partner in the agricultural team at Michelmores solicitors.

She says what is now UK domestic legislation is reflective of a “snapshot” of what EU law looked like on 31 December 2020 and does not encompass changes that have been made in the EU since then.

These include changes to feed ban rules, which now allow the use of insects as feed in European pig and poultry production.

“While this is not yet applicable to UK farmers, this decision is reflective of where we could and should be going,” she adds.

The World Wide Fund for Nature (WWF) is among the non-government organisations driving a campaign to change this.

In its 2021 Roadmap to accelerating insect protein in UK feeds (PDF) report, the WWF urges the UK government to introduce legislation that permits the use of insect meal in pig and poultry feed and broadens the range of feedstocks that can be used to farm insects.

It also says pig and poultry sectors need to advocate for the legislative changes required.

Feeding black solider fly larvae is, however, permitted for feeding to pigs under current UK legislation (see “Understanding the black soldier fly”).

Prof van Huis adds that the cost of insect meal is currently still higher than the comparable price of soya bean. This presents another challenge to its wide-scale adoption.