Net energy content of different grass species

The content of net energy for lactation, crude protein and crude fibre of fifteen grass species were compared. Samples were collected in field trials during the first, second and third growth cycle of a total of five growth cycles per year. Perennial ryegrass (Lolium perenne L.) produced the forage with the highest content of net energy for lactation at most sampling dates. Meadow fescue (Festuca pratensis Huds.) also had a high energy content as well. During the first growth cycle, Italian ryegrass (Lolium multiflorum Lam.) was comparable to perennial ryegrass. During regrowth cycles the energy content of this species was lower and decreased at a faster rate than the other species. The ranking of energy content of the grass species was different depending when the plants were compared: at the same age or at the same stage of development. Climatological factors influenced the energy content of the grass species, which caused important differences between the years. The ranking order of the grass species was only slightly influenced by climatological factors.