Intake and apparent digestibility of perennial ryegrass haylages fed to ponies either at maintenance or at work

Different lots of perennial ryegrass haylages were controlled for dry matter, buffering capacity, pH, soluble and ammonia nitrogen, lactic and monocarboxylic acids, alcohols, crude protein, crude fiber, gross energy, and ash. Net energy (UFC), and organic matter, were calculated. These forages were then fed to seven ponies, weighing on average 330 kg, during two different digestibility trials at maintenance or submitted to different workloads. Voluntary intake was measured, and digestibility coefficients were calculated for dry matter, organic matter, gross energy, crude fiber, and crude protein, using acid-insoluble ash as internal marker. Differences were found for the chemical composition of the three studied haylages; these differences can be ascribed to the different vegetative stage of the perennial ryegrass at harvesting. The conservation quality of these haylages was good or very good. Intakes were similar to those observed with hays. The OM digestibility of the haylages have been found to be lower than those measured for silages, and similar to those measured for good hays in literature. Increasing workloads decreases the dry matter and organic matter digestibilities; the same trend was found for gross energy, and crude fiber.