A review of the effects of mechanical treatment of forages on fermentation in the silo and on the feeding value of the silages

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Abstract
The effect of mechanical damage (laceration, chopping, etc.) on fermentation and losses of herbage in the silo and the effect of the resultant silages on digestibility, intake, and subsequent animal production are reviewed. Physical damage was found to increase rate of fermentation and also tended to reduce losses from the silo compared with long-cut material. The effect of physical damage on digestibility was small and variable; many determinations were confounded with intake and consequently no firm conclusions could be drawn. Intake of silages by sheep increased markedly with increasing fineness of chop, but no optimum chop length for maximum intake was determined. Growing and adult cattle also increased silage intake as fineness of chop increased, but the response was smaller than with sheep and showed little justification for fine chopping (< 25 mm); however, most cattle comparisons were made in association with concentrate supplementation which limits extrapolation of results to sole ration or supplement to pasture feeding systems. Despite responses in intake to increasing fineness of chop, production responses from sheep and growing and lactating cattle were small and often not significant. It was concluded that little justification could be found for fine chopping in terms of improved animal production, but further studies were required under New Zealand pastoral conditions if this conclusion is to be confirmed and the reasons why determined.