Effect of storage system and dry matter content on the composition of alfalfa silage

The objectives of this study were to evaluate the effects of dry matter (DM) content and three different storage systems on the quality of alfalfa ensiled on commercial farms. Alfalfa silage samples were collected from 21 bunker silos, 20 silos that limited oxygen infiltration, and 19 tower silos on 43 commercial dairy farms. Storage system and DM content were confounded because silages from bunker silos generally were wetter than silages from O2-limiting and tower silos. There was no effect of storage system on crude protein content of the silages. However, silage from bunker silos had higher concentrations of nonprotein N, NH3 N, and acid detergent insoluble N than did silages from the other two storage systems. The proportion of total N in neutral detergent insoluble N minus acid detergent insoluble N was greatest in silage from O2-limiting silos. Fiber components were affected by storage system; silage from bunker silos had the greatest concentration of acid detergent fiber and neutral detergent fiber. Concentrations of acid detergent fiber and neutral detergent fiber were higher in wetter silages from bunker silos, but DM content did not influence fiber content of silages from O2-limiting and tower silos. Concentrations of total organic acids, acetic acid, and butyric acid were highest in silages from bunker silos. The general effects of DM on the quality of silages obtained from commercial dairy farms were similar to results obtained from laboratory-scale silos