Two intensive forage processing mechanisms, utilising either shredding or impact processing, were used to investigate physical disruption of wilted alfalfa and whole‐plant corn as a potential means to improve fibre digestion. 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. The goal was to achieve a PLI of at least 60%. Impact processing created more physical disruption than shredding, and the former method was able to achieve the desired PLI goal. Although impact processing significantly reduced particle size of both wilted alfalfa and whole‐plant corn, more than 40% of alfalfa particles were longer than 6.3 mm when the PLI of greater than 60% was achieved. The mean particle‐size of the kernel fraction of processed whole‐plant corn was less than 1 mm after processing with the impact processor. Impact processing of wilted alfalfa significantly increased the rapidly soluble fraction and increased the rate of degradation of DM and potentially digestible fibre (pdNDF) during an in situ digestion experiment. Intensive mechanical processing has the potential to improve ruminant animal utilisation of forage crops through improved fibre digestion.

An intensive processing mechanism that combined impact and shredding was applied to create physical disruption of whole-plant corn as a means to increase in situ dry matter (DM) digestion in lactating dairy cows. A ratio of treatment leachate conductivity relative to that of an ultimately processed treatment, defined as a processing level index, was used to quantify material physical disruption. Two processing levels were compared to a control treatment, which applied conventional chopping and kernel processing. The non-grain fraction was substantially size-reduced by processing such that only 28% to 51% by mass of this material remained greater than 6.4 mm length. After processing with the experimental processor, greater than 85% of kernels passed through a 4.75 mm screen, and the corn silage processing score (CSPS) was 18 to 27 percentage points greater than the control. The highly fiberized material was more compliant; thus, compacted density was 9% to 17% greater than the control. During in situ digestion experiments, processing significantly increased the rapidly soluble DM fraction by 10 percentage points and the extent of DM disappearance by 5 percentage points through 16 h incubation.

HighlightsA 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.