That project was aimed at boosting circularity in animal feed; it was run by a consortium comprising 13 companies and research institutes such as SFR and Wageningen Livestock Research. The work got underway in 2018, with the teams exploring how to increase the use of co-products and residues as well as novel proteins as feed materials – the objective was to improve resource use efficiency, close nutrient cycles and thus aid the circular bioeconomy.
Dissemination of the results of the project is currently underway.
Alternatives to soybean meal
One work package, which was led by Ellen van Eerden, poultry nutrition researcher at SFR in the Netherlands, investigated how a particular processing technique might boost the protein level in legumes such as faba beans and lupins to encourage greater uptake of these crops in pig and broiler diets, regionally.
While those legumes contain a reasonable level of protein, it is lower than that of soybean meal (SBM), and there were concerns this aspect would limit their application in feed for monogastric animals, said the poultry nutrition expert.
The team investigated a dry separation technique, dubbed air classification, to concentrate the protein in those crops. The raw materials – lupins and faba beans – had to be fine milled prior to undergoing the air classification process to ensure separation of the starch and protein fractions. A lab-scale air classifier was used for the pilot experiment.
The process resulted in protein rich fractions, with protein levels nearly twice as high as the amount in the starting material. However, the researchers also saw accumulation of anti-nutritional factors (ANFs) in those fractions, particularly for the faba beans, explained Van Eerden.
In addition to the legume work, the team assessed grass protein isolates from two different suppliers along with lucerne (alfalfa) and red clover protein paste via wet-chemical analysis. Following freeze drying, they saw that all four products contained a satisfactory level of protein. “But when we looked at in vitro protein digestibility, we saw quite a difference in levels between the two grass protein isolates.”
The quality of the end-product depends on the isolation procedure used, she stressed. The team also saw that the red clover paste had quite low in vitro digestibility coefficients.
The nutritionists then conducted in vivo digestibility testing of novel proteins, in broilers. They wanted to establish the feeding values of commercially available alternative inputs, with SBM as a reference. They studied faba bean protein concentrates, grass protein isolates, along with pea derived protein and two commercially supplied insect protein products.
The broilers were kept on a commercial standard diet until day 14, when they then switched to one of the experimental diets. “We kept them on the experimental diets until day 24. During the last three days of the trial, we collected excreta to ascertain fecal digestibility coefficients, along with intestinal content to determine the ileal digestibility coefficients.”
The results showed that the faba bean and the pea protein concentrates had high digestibility coefficients for protein, in the same order of magnitude as SBM. The digestibility coefficients for fat were also higher in the faba and pea protein products, reported Van Eerden.
The insect proteins performed quite well, with only slightly lower digestibility coefficients for protein compared to SBM, she said. “Furthermore, it is noteworthy that both insect proteins had significantly higher digestibility coefficients for fat than the soybean meal.”
The grass protein isolate under-performed compared to SBM, not only on the crude protein aspect but also in relation to fat digestibility.
The findings from the ileal digestibility analysis for amino acids corresponded with the data from the fecal analysis for protein, and there were no negative effects on digestibility or performance arising from any potential ANFs in the faba bean or pea protein concentrates, reported Van Eerden.
Regardless of the nutritional value, from an economic perspective, using faba and pea protein products in feed applications today is too costly, given the ongoing demand from the food sector for such inputs, concluded Van Eerden.
“The air classification process creates both starch rich and protein rich fractions from legumes so, perhaps, when there is more food industry exploitation of the starch fractions, there would be greater availability of protein fractions for inclusion in feed formulations.”