As one of the biggest contributors to the overall carbon footprint of pig diets, there is a lot of focus on soya at the moment.
New legislation is set to come in at EU and UK level next year aimed at ensuring imports of commodities like soya are produced sustainably, raising questions about soya’s availability and price next year.
So the search for alternatives, ideally home-grown ones, particularly in pig and poultry diets, has never been more important.
Reducing reliance on this imported protein is a key priority for pig and poultry feed manufacturer ABN.
Pulse alternative
As part of its long-term strategy to reduce the carbon value of feed in pig diets, it is undertaking significant research into potential alternative proteins, in particular looking at the commercial viability of pulses as a sustainable raw material to either replace or reduce soya use.
This work aligns very closely with ABN’s work with its poultry team, as a key partner in the Nitrogen Climate Smart (NCS) project.
NCS is a collaborative project, led by the Processors and Growers Research Organisation (PGRO), with the dual aims of increasing pulse and legume cropping in UK arable rotations and displacing up to half of the soya imported into the country for use in animal feed.
While this work has focused solely on poultry diets, the project has already recognised the extensive research from SRUC’s Green Pig Project, finding the concept of replacing soya with pulses as proven and a viable opportunity.
ABN has been working on its own independent research to evaluate the commercial viability of doing so.
Beans are a more typical raw material in a pig diet than, for example, poultry feed, but there remains a need to look at different ways of further reducing the amount of soya being used, and its carbon impact, according to Dr Steve Jagger, ABN senior pig nutritionist.
“As part of our commitment to look at alternative proteins, we have been working on a series of commercial-scale trials with our customers, including sets of finishing and weaning pig trials using pre-processed pulse-rape blends,” he said.
ABN is building a database on pulse analysis, and a dataset of feed production parameters. Early animal performance results are promising in most areas, but the next stage is to look further into the need to apply pre-treatments to counter anti-nutritional factors, and to also consider the right variety of pulse to optimise performance.
Commercial constraints
Those previous studies by the Green Pig Project, undertaken by SRUC researchers alongside a consortium of academic and industry-relevant organisations, have already indicated that soya can be replaced with beans in pig diets.
That work investigated whether home-grown peas and faba beans could replace imported soya in grower and finisher pig diets. It demonstrated that there was no detrimental effect on performance, carcase weights and back-fat measurements, suggesting peas and beans are a viable home-grown alternative to soya bean meal in nutritionally balanced grower and finisher pig diets, with huge carbon saving potential.
However, it did note that there are constraints on commercial availability that would need to be addressed to fully exploit the results of that study, and this effectively led to the next steps that ABN is looking to explore.
Anti-nutritional properties
“Beans are relatively low in digestible amino acid levels, particularly methionine. When directly comparing beans and soya, energy levels are very similar, but proteins in beans are about half the value of soya, and the methionine figure is much lower,” Dr Jagger said.
While this can be corrected in formulation, to make the product perform as well as soya, it adds cost.
“There are also anti-nutritional properties found in beans, specifically vicine and convicine, that disrupt the metabolism in mammals and can, therefore, reduce feed efficiency,” he said.
“We can’t easily reduce vicine and convicine by heat processing, but there are other techniques that can cut their presence, with variety choice the main one.”
There has been work with plant breeders on varieties that are naturally lower in vicine and convicine to get the yields as high as possible to make them more viable for the grower.
Trypsin inhibitor is another anti-nutrient present in beans, and in ABN’s own work, done a few years ago, it was found that as you increase it, you reduce the digestibility of the nutrients. It plans to further explore research showing heat processing can reduce this.
Finishing pig trials
In its trial work, ABN has been considering whether a pre-processed pulse-and-rape blend could replace or significantly reduce the use of soya in pig rations.
Trials with 4,000 finishing pigs from 40kg to slaughter looked at four levels of replacement, from full inclusion of soya all the way down to complete removal.
It was undertaken through three phased diets at the growing, intermediate finishing and final finishing stages.
During the three growth stages, different inclusions of pre-process pulse and rape blends were used in the full replacement of soya.
The trial, completed at the end of 2023, showed that the performance of finishing pigs was not significantly affected when pigs were fed diets where soya had been replaced with the extruded blend of UK-produced whole rape and beans.
“The P2 of pigs was reduced as the level of soya was reduced, potentially indicating that the amino acid digestibility was higher in the alternative protein, while the carbon footprint of the pigs was significantly reduced by replacing soya with the rape and bean blend,” Dr Jagger added.
There was, however, a financial penalty when soya was reduced, reflected in an increased cost per kilo liveweight gain and a reduced margin over feed, which will be a focus of future research.
The company also wants to look at how raw beans, processed beans and a processed rape-bean blend it has trialled to date compares to soya.
Weaner pig trials
In weaning pig trials, with pigs from 10-40kg, ABN has looked at another pre-processed pulse-rape blend. “While soya cannot be completely cut from the weaning pig diet using the blend alone, we have been able to significantly reduce it and achieve good performance,” Dr Jagger added.
“Growth rate was maintained, and while intake was increased, the carbon reduction was significant,” he said.
From these trials, ABN has seen an approximate 40% reduction in the carbon value of feed, including land-use change, when comparing the full soya inclusion against the highest pre-processed pulse-rape blend diet.
These calculations, based on GFLI figures, represent significant reductions and are ‘extremely encouraging’, Dr Jagger said.
“Our focus remains to develop products to help the industry reduce its carbon values, but this requires buy-in across the entire supply chain. Ideally, we would want a product where we can reduce pre-treatments and processing,” he added.
“We therefore need alignment from the arable farmer to animal feed companies, pig processors and the food service and retailers to help initiate this transition.”
Nitrogen Climate Smart project
The NCS project was launched last year to encourage farmers to make the most of opportunities around pulse production and reducing carbon dioxide emissions.
The Processors and Growers Research Organisation (PGRO) brings together 17 partners and hundreds of farms for the project, which is funded by Defra’s Farming Innovation Programme and delivered by Innovate UK.
Its aims include:
- Bringing about a reduction of 1.5mt carbon dioxide equivalent a year in emissions from UK farming or 54% of the maximum potential for the industry.
- Increasing pulse and legume cropping in UK arable rotations from 5% to 20%.
- Replacing up to 50% of imported soya meal used in livestock feed rations with home-grown legumes.
Experts discussed the NCS project at Cereals 2024 in Hertfordshire, alongside a selection of pea and bean varieties.
“Farmers are keen to know more ways to grow pulses, both in the conventional sense and with the new trends, such as intercropping,” said PGRO CEO Roger Vickers, who highlighted the crop rotation opportunities that may be available within the Sustainable Farming Incentive.