Through extensive research and commercial-scale trials, ABN is exploring the use of pulses, such as faba beans, as a sustainable alternative to soy in pig feed.
“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 utilizing pre-processed pulse rape blends,” explains Dr Steve Jagger, ABN’s senior pig nutritionist.
ABN is building a database on pulse analysis, and a dataset of feed production parameters.
While previous research, such as the SRUC-led Green Pig Project, demonstrated the potential of home-grown beans as a substitute for soy in pig diets, ABN's current focus is on assessing the commercial feasibility of this shift.
This work aligns very closely with the research ABN is involved in with its poultry team, as a key partner in the Nitrogen Climate Smart (NCS) Project, a PGRO led consortium, funded by Defra’s Farming Innovation Program and delivered by Innovate UK, and which is aimed at increasing pulse and legume cropping in UK arable rotations, but also displacing up to half the soy imported into the UK for use in feed.
Trial results
Dr Jagger outlines the findings from the ABN trials with 4,000 finishing pigs. The studies evaluated varying levels of soy replacement with a pre-processed pulse and rape blend. The trials ran from 40kg to slaughter across three diet phases, at the growing, intermediate finishing and final finishing stages. "The results showed no significant decline in performance when soy was replaced by the blend, and the carbon footprint was notably reduced," he reports.
Additionally, pigs fed the blend had lower P2 (backfat thickness), suggesting improved amino acid digestibility.
“With finishing pigs, we can fully replace soy with other materials since their protein requirements are lower. However, this comes with a cost, which is why we are not already formulating diets that way today,” Dr Jagger tells FeedNavigator.
The reduction in soy led to higher costs per kilo of liveweight gain and a decrease in margin over feed. This will be a focus of future research, with plans to compare the performance of raw and processed beans against the blend and soy.
In weaner pig trials (10-40kg), the pulse and rape blend allowed for substantial soy reduction without compromising growth rates, although feed intake increased. These trials showed a 40% reduction in the carbon value of feed, representing considerable progress toward more sustainable pig diets.
“In weaner pig diets, the higher protein requirements make it challenging to replace soy, as it provides a well-balanced amino acid profile. However, we are currently evaluating the use of high-protein sunflower meal for growing weaner pigs. One treatment in the ongoing trial has successfully achieved full soy replacement. With sunflower meal offering around 46% protein, we are looking forward to seeing the overall results,” continues the pig nutritionist.
Not an easy fix
Despite the success with the pre-processed pulse and rape blend, challenges remain.
“Beans have low levels of digestible amino acids, especially methionine. Although their energy content is comparable to soy, their protein value is about half, and methionine levels are significantly lower," says Dr Jagger.
While these deficiencies can be adjusted through feed formulation to match soy’s performance, doing so increases costs.
Pulses also contain anti-nutritional factors (ANFs) like vicine, convicine, and trypsin inhibitors (TIA), which can reduce feed efficiency.
“Vicine and convicine can disrupt the metabolism in mammals, and can therefore reduce feed efficiency,” says Dr Jagger.
“We can’t easily reduce vicine and convicine by heat processing, however, there are other techniques that can be applied to reduce their presence, with consideration to breed variety being the main one.”
There are varieties that are naturally lower in vicine and convicine, and there has been a lot of work in this space with plant breeders to get the yields from those varieties as high as possible, to make them more viable for the grower.
In ABN’s previous research, the team observed that higher levels of trypsin inhibitors reduced nutrient digestibility. However, studies have shown that heat processing can mitigate this effect, and ABN plans to explore this approach in greater detail, he adds.
Dr Jagger emphasized that while ABN is committed to reducing the carbon footprint of pig feed, success will require collaboration across the supply chain—from feed producers and farmers to retailers. "Our goal is to develop products that reduce carbon values, but achieving this requires support from all stakeholders.”
