Hay is an usual component of horse diet. Nevertheless, it is suspected to provide some spores causing chronic obstructive pulmonary disease. Grass silage has been suggested as forage in the diet to overcome the problem. It was therefore of interest to assess the nutritive value of grass silage in horses.

Three silages with different dry matter (DM) content were compared. Since horses dislike grass silage with a low DM content, wilted silages only were compared. The first two were first cut grass silages with a low DM content at 427.3 g/kg (LGS) or a medium DM content (661.7 g/kg - MGS). They were compared with a second cut silage from grass grown under very dry conditions (HGS - 787.5 g/kg). The grass was ensiled in square big bales. The 3 silages were offered alone and ad libitum to 4 sport horses in 3 consecutive periods,each silage being offered during one period.