Egg producer’s verdict on best alternative protein for layers

From manure to processing, emissions from egg production can be tricky to manage.

But replacing some, or all, of the soya in a standard flock’s diet with other proteins is the one factor possibly achievable in every system – if the costs stack up.

Feed is the biggest source of emissions on free-range egg farms because diets are high in protein and much of that is sourced from soya.

See also: Which home-grown proteins might replace soya in poultry diets?

Soya

Typically, together with soya oil, it accounts for 21% of a laying hen’s diet.

Replacing these could provide a “silver bullet’’ to substantially reduce the carbon footprint of eggs, reckons farm operations manager Alistair McBain, at Duncan Farms.

He runs a vertically-integrated egg producing and packing enterprise in Turriff, Aberdeenshire.

There are good reasons why poultry farmers feed soya. It is cheap, has an excellent amino-acid profile with high digestibility and, compared with other protein sources, has relatively few anti-nutritional factors.

Unlike alternatives, particularly industry by-products, it does not need to be constantly analysed to assess any variabilities in nutritional quality.

Pros and cons of soya-free diets

As a 2022 Nuffield scholar, Alistair explored the practicalities and opportunities of moving to soya-free poultry diets.

He examined the pros and cons of alternative proteins including grain legumes (also known as pulses) and insect protein.

Single-cell proteins, which are derived from the biomass of micro-organisms such as algae and yeast can be used as poultry feed.

As can industry by-products including dried distillers’ grains, processed animal proteins and biscuit meal,

Individually, however, none could be a complete substitution for soya because of the sheer volume needed, Alistair concluded.

They would instead be needed in combination to significantly reduce or replace it completely.

Cost

This would come at a higher cost compared with soya, and that means producers would need to be paid more for their eggs.

Alternatively, the price of these proteins would have to come down, perhaps through measures such as scaling up insect protein production.

“If customers are willing to pay more, there needs to be differentiation of meat or eggs from poultry fed on soya-based diets, and those on non-soya but more expensive diets,’’ Alistair suggests.

In many cases, synthetic amino acids would need to be added to diets alongside these proteins to produce a feed with the correct nutritional profile for poultry.

Alistair concluded from his research that insect protein from black soldier flies offers one of the greatest potentials to reduce the carbon footprint of eggs.

Their potential for upcycling food waste gives the possibility to achieve a negative carbon footprint from their use as a feed.

UK law on animal proteins

In the UK, legislation controlling the feeding of processed animal proteins to livestock means only live insects can be fed to poultry, although that law is expected to change to allow insect protein meal to be fed.

A handful of poultry producers are currently feeding live insects to laying hens by distributing live larvae in their laying sheds as enrichment, says Alistair.

“This requires increased labour, and it cannot be relied upon as a feed source as it’s not possible to guarantee each bird will receive the same amount of larvae, or any larvae at all.’’

A typical crude-protein analysis of insect protein meal is 52%, but only if insects are themselves fed higher grade feed stocks.

The current cost of producing wet larvae is estimated to be in the region of £513/t at 30% dry matter. When dried down to a meal, that cost is around £940/t.

As well as the high capital requirement for producing and processing insect protein, there are other major overheads.

These include the electricity used to operate the ventilation systems and machinery associated with the process, as well as labour costs.

Case study: Alistair McBain, Duncan Farms, Turriff, Aberdeenshire

Alistair McBain © Grant Anderson

Alistair McBain switched 50% of the protein component of diets from soya to home-grown faba beans (also known as field beans) and sunflower meal.

This has halved the carbon footprint of eggs produced by 56,000 layers at Duncan Farms.

The business produces free-range eggs from 580,000 Hy-Lines and Shaver Browns across 13 sites, suppling these to M&S, Lidl and Morrisons.

Sustainability is central to business policy at the free-range egg producer and part of that is a move away from use of imported soya.

For the past four years, feeding of different home-produced proteins has been trialled on a proportion of the flock.

Initially it took the form of oilseed rape and faba beans, but palatability challenges were encountered with oilseed rape.

“After the first review we decided to take all the oilseed rape out of the diet because it was affecting palatability,’’ Alistair McBain explains.

He adds that sunflower meal has now replaced the oilseed rape element of the ration.

While the alternative proteins have made a significant difference to the eggs’ carbon footprint, what they have also done is reduce egg weight, by an average of 2-3g.

This is a consequence of how the hens digest amino acids in these feed sources. It means fewer eggs achieve the bigger sizes that capture the premium price points.

In general, hens produce an egg-size smaller than they might have previously laid. In an attempt to address this, additives in the form of enzymes are being trialled in the ration.

High feed cost

Alistair says buyers, and ultimately the consumer, need to recognise that producing food sustainably does come at an additional cost and that needs to be reflected in the egg price.

“The reality is that switching to alternative proteins makes it more complicated in terms of feed formulation, and it is more expensive, so the big question is: who should pay for sustainability?’’ he asks.

“There is not enough margin in agriculture to support carbon reduction, so all the extra costs do need to be reflected in the price consumers pay for food, in our case, eggs.’’

The business is in its fourth year of growing faba beans with 61ha (150 acres) planted in mid-March.

The region does not have the ideal conditions for growing the type of protein crops that can be used in poultry diets, so fields for beans have to be carefully chosen.

“We use our earlier ground for growing faba beans. The beans have a long growing season too – they are the first crop to go into the ground in spring and the last to be harvested in the autumn.’’

As an integrated business, Duncan Farms also grows 90% of the cereals it needs for the hens’ feed.

Solar panels and wind turbines allow all its free-range sites to contribute significantly to their electricity requirements from renewable energy.

There is also biomass heating in all of its pullet-rearing sheds.