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Microscopic and chemical changes during the first 22 days in Italian ryegrass and cocksfoot silages made in laboratory silos |
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| Authors: | ANA L WINTERS P A WHITTAKER R K WILSON |
| Institution: | Biology Department, Maynooth College, Ireland;An Foras Talùntais, Castleknock, Dublin, Ireland |
| Abstract: | Although many aspects of grass silage have received intensive study, the changes that take place within the grass blades during ensilage have received little attention. In two factorial experiments Italian ryegrass (cv. Lemtal) and cocksfoot (indigenous) were ensiled in laboratory silos (capacity 0·2 kg) with the grass under pressure (700 Pa) and subjected to two treatments (with or without 3·31 t For each sampling date transverse sections of grass laminae were examined and changes in the cross sections of the protoplasts and of cells, as defined by the cell walls, were recorded. These data were used to calculate the ratios of protoplast to cell volumes at each sampling date. Each silage was analysed for dry matter, pH, lactic acid, VFA, ammonia and glucose. The distance settled by the silage (a measure of decrease in silage volume) and the silage conductivity were also recorded. Both of the untreated grasses yielded silages with typical lactic acid levels and pH values. In all of the silages there was a marked shrinkage of the plast within the space defined by the cell wall. The ratio of protoplast to cell volume eventually stabilized at 0·4. The formic acid-treated grasses reached this level by day 1 but a longer period was required by untreated grasses. It is suggested that the decrease in silage volume is related to the lactic acid content of the liquid phase due to their close relationship in silages produced from untreated grasses ( r = 0·97***). |
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