Intensive mechanical processing of forage crops to improve fibre digestion

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.