Altering Physical Properties of Wilted Alfalfa by Impact – Shredding Processing

Highlights A screenless hammermill utilizing impact and shredding was used to process wilted alfalfa. Processing increased specific surface area and ruptured plant cells as quantified by a processing level index. Processed material was more compliant than the chopped material resulting in 26% to 56% greater compacted density. Processing reduced silage pH and increased fermentation acids compared to the chopped silage. Abstract. Intensive mechanical processing of wilted alfalfa could potentially increase ruminant utilization of alfalfa. 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, indicating processing improved silage quality. Keywords: Alfalfa, Density, Haylage, Impact, Particle-size, Shredding.