Production and nutrient composition of forage legume fractions produced by juicing and leaf stripping

ABSTRACT

The large-scale import of soybean products into the EU decreases the self-sufficiency of livestock production. The fractionation of grassland forage crops presents an opportunity to locally produce protein-rich feed for monogastrics. Two promising fractionation methods, twin-screw press juicing and leaf stripping, were evaluated in parallel in field experiments established in Norway and Sweden to compare the nutrient composition and yield of the resulting biorefined and residual fractions. The clearest delineation between the methods was in the ash-free neutral detergent fibre (aNDFom) concentration, with juicing producing a biorefined fraction with a lower aNDFom than leaf stripping. Variability in the allocation of crude protein (CP) and biomass to the biorefined fractions occurred in both methods between cuts and locations and is likely due to differing stand characteristics and inconsistency in machine functionality. Additional work is needed to understand how characteristics such as stand density, botanical composition, and plant phenological stage impact each fractionation method’s ability to allocate protein, fibre, and biomass into the resulting fractions. Future studies should focus particularly on determining standardised settings for leaf stripping machinery based on a range of stand characteristics to ensure consistency in the yield and nutrient composition of the resulting fractions.

KEYWORDS:

• Biorefinery
• clover
• crude protein
• forages
• fractionation
• local protein feed
• monogastric
• neutral detergent fibre
• nutrient composition
• ruminant

Acknowledgements

The authors acknowledge Eric Juncker of Trust’ing – Alf‘ing for supply of the PremAlfa Mini leaf stripping machine used in this study. Nutrient composition analyses were performed under the supervision of Paolo Bani at the Department of Animal Science, Food and Nutrition – DIANA, Università Cattolica del Sacro Cuore. Boel Sandström, Olav Tjernström, Malin Barrlund, and Anders Wiik assisted with field data collection and organisation of data. The study was conducted using material and equipment from Röbäcksdalen, and SITES (Swedish Infrastructure for Ecosystem Sciences), a national coordinated infrastructure, supported by the Swedish Research Council.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Data sets analysed during the current study are available from the corresponding author on reasonable request.

Author contributions

Conceptualisation, D.P. and S.A.; methodology, B.M., D.P., and S.A.; statistical analysis, B.M., D.P., J.F., and S.A.; data curation, B.M., D.P., J.F., and S.A.; writing – original draft preparation, B.M.; writing – review and editing, B.M., D.P., J.F., and S.A.; visualisation, B.M., D.P., J.F., and S.A.; project administration, D.P. and S.A., funding acquisition, D.P. and S.A. All authors have read and agreed to the published version of the manuscript.

Additional information

Funding

Financial support for the ProRefine project was provided by funding bodies within the H2020 ERA-NET project, CORE Organic Cofund, and with cofunds from the European Commission.

Notes on contributors

Brooke Micke

Brooke Micke is a PhD student at the Department of Crop Production Ecology, SLU in Umeå. Her research focuses on increasing the sustainability of forage production in Sweden through the utilisation of new harvest methods and integration of native legume species.

Steffen Adler

Steffen Adler is a researcher at the Department for Grassland and Livestock at the Norwegian Institute of Bioeconomy Research. His areas of interest are biorefinery of forage crops and ruminant nutrition.

Johannes Forkman

Johannes Forkman is a senior lecturer in Statistics and docent in Biometry at the Department of Crop Production Ecology, SLU in Uppsala. He is an expert on statistical methods for agricultural field experiments.

David Parsons

David Parsons is a professor in Crop Production Science at the Department of Crop Production Ecology, SLU in Umeå. His current research focuses on combining agronomy, modelling, and remote sensing of crops.