The degradability characteristics of a wide range of grass silage types have been studied using the in sacco technique over a 48-hour period. Each silage was examined in three steers on two occasions, with pairs of bags being withdrawn at each sampling time. The steers had an average live weight of 270 kg and were fed once daily on silage, molassed sugar beet pulp and barley meal (5:3:2 on a dry matter basis), which supplied an average of 55 MJ ME per head daily.

The losses of dry matter, nitrogen, cell contents, hemicellulose and cellulose were followed. For the carbohydrate fractions, modifications of the methods of van Soest were used. For each of these components, asymptotic equations of the form: p = a + b (1-e−ct) were fitted, where a and b represent percentages of the amounts originally present in silage, c represents the proportional rate of degradation and t represents hours of incubation.