Influence of some chemical and biological additives on the fibre fraction of lucerne on ensilage in laboratory silos

Summary Laboratory silos were prepared from lucerne (Medicago sativa)which had been treated with a number of chemical and biological additives. The additives used were the acid additive, formic acid, the sterilant, formaldehyde, the oxidative enzyme, glucose oxidase, and the starch hydrolysing enzyme complex, Termamyl. Silos were prepared in duplicate and pairs of each treatment were opened at 0, 2, 9, 20 and 60 days ensilage. The pH, volatile fatty acid patterns and dry-matter yields were determined and the composition of the residual fibre was determined for cellulose, hemicelluloses, lignin and phenolic acids. The only treatment to enhance the rate of fall in pH was formic acid. The rate of decline in pH of the silages treated with glucose oxidase was not significantly different from the other treatments. The starch degrading enzyme complex did enhance the loss of starch from the lucerne but it did not appear to have any significant effect on the silage characteristics measured. No loss of true lignin was observed from the fibre but most of the phenolic acids present were removed. All the treatments appeared to have a significant effect on the cellulose content which was in contrast to earlier work on ryegrass silages where no effect was observed. On the other hand, the treatments had less effect on the hemicellulose fraction than was observed in the previous work with ryegrass. These results can be explained by differences in the structures of the fibres from lucerne and ryegrass.