Altering physical properties of wilted alfalfa by impact – shredding processing

Authors: PINTENS, DAVID - University Of Wisconsin; SHINNERS, KEVIN - University Of Wisconsin; FRIEDE, JOSHUA - University Of Wisconsin; DIGMAN, MATTHEW - University Of Wisconsin; Kalscheur, Kenneth

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2023
Publication Date: 3/27/2023
Citation: Pintens, D.A., Shinners, K.J., Friede, J.C., Digman, M.F., Kalscheur, K. 2023. Altering physical properties of wilted alfalfa by impact – shredding processing. Applied Engineering in Agriculture. 39(2):187-195. https://doi.org/10.13031/aea.15168.
DOI: https://doi.org/10.13031/aea.15168

Interpretive Summary: The objective of this research evaluated how a novel impact and shredding processing device affected the physical and fermentation properties of intensively process wilted alfalfa, affected power requirements to operate the process, and determined the effect of processing on DM content and particle size of the alfalfa. This research demonstrated that intensive mechanical processing was an effective method to cause physical disruption of wilted alfalfa and that the physical disruption was the result of both impact and shredding. Fermentation properties were improved by processing. Although the intensive mechanical processing required significant energy, it demonstrated the ability to produce unique physical properties of the processed alfalfa that could improve nutrient utilization in ruminants. While processing decreased particle size, the remaining length was sufficient for feeding to ruminants. This research will be of interest to dairy producers, researchers, and ruminant nutritionists interested in improving the value of forages in ruminant diets. Improving the value of forages for ruminants will increase the value of forages both nutritionally and economically resulting in more sustainable ruminant production systems.

Technical Abstract: Intensive mechanical processing of wilted alfalfa could potentially increase ruminant utilization of alfalfa haylage. A novel forage processing mechanism which combines impact and shredding was used to investigate intensive physical disruption of wilted alfalfa. Physical disruption was quantified by a processing level index (PLI) defined as the ratio of treatment leachate conductivity relative to that of an ultimately processed treatment. Utilizing this index, four processing levels defined by the number of passes through the processor were compared to a control treatment of conventionally chopped material. Processing three times through the processing device achieved a PLI of greater than 60%, with the greatest increase in PLI occurring in the first pass through the device. Processing reduced particle size, but 45% to 56% of the material dry mass was greater than 6 mm at the greatest processing level. Processing severely disrupted the mechanical structure of the stems, making them more compliant resulting in 26% to 56% greater compacted density than the chopped control. Processing reduced silage pH and increased fermentation acids compared to the chopped silage.