Chemical analysis of the feed in order to identify all related substances should be combined with investigations of physiological responses by the animal at the time of feed intake. For the future it would be desirable to include more silage compounds in routine forage analysis to obtain more data about possible relationships among specific compounds. To elaborate more profound causalities the respective features need to be better characterized and new features should be created. Studies involving integration of physical and physiological regulation would be an important step forward, for example the possible impacts of silage chop length on fermentation and physiological processes. Silage production will remain a key part in ruminant production systems across Europe. This demands continuing approaches for production of high quality silages involving improvements in management practise to minimise losses and maximise the preservation of the inherent feeding value of the parent crop.
At low DM concentrations, early harvested grass silages displaying restricted fermentation seem to be a preferable quality, promoting a possible increase in DMI, even though the experimental evidence is ambiguous, but more clearly inducing a positive production response and increased feed efficiency by lactating cows. Little production responses will occur from wilting when the ensiled material is treated with formic acid. Wilting mainly seems to induce positive responses on DMI of early harvested material treated with inoculants or untreated material. Generally, nutrient recovery and quality is good when fermentation has been restricted with acid-based additives in low DM grass silages. To further minimise the risk of clostridial fermentation, low DM grass should preferentially be wilted to a DM content of 300 g kg-1. This is also the level of DM content often recommended giving smallest total losses, i.e. in the field, from fermentation, and from effluent. The importance of quick attainment and maintenance of anaerobic conditions in the silo to limit proteolytic activity and unwanted microbial growth is inevitable. Changes in chemical composition during ensilage impact the energy supply to ruminal microbes. Paralleled with the increase in degradable N compounds it will affect the balance of absorbed nutrients. Adjusting the ratio of degradable protein and fermentable energy supply in the rumen has been suggested to be the best opportunity when trying to improve the efficiency of N use.
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