PERENNIAL RYEGRASS CULTIVAR EFFECTS ON INTAKE OF GRAZING SHEEP AND FEEDING VALUE

The use of animal trials in routine evaluation of grass cultivars unde r grazing is expensive and space-and time-consuming. Therefore, there is a need to find cultivar morphological traits enhancing animal produ ction under grazing which could be used to evaluate and breed grass cu ltivars. The morphogenesis of four cultivars of perennial ryegrass (Lo lium perenne L.) was compared in relation to their intake by grazing s heep. Sheep intakes were estimated by following the consumption of mar ked tillers over 4 days of grazing, after 3, 4 and 5 weeks of growth a nd at the same allowance of 1.7 kg DM day(-1) sheep(-1). Significant d ifferences in intake were found between cultivars but the order was ma nagement-dependent. Intake under grazing was positively correlated wit h the green lamina mass above 10 cm. The same cultivars were fed to sh eep in individual crates. Ingestibility, in vivo digestibility and pal atability were assessed and significant differences were found between cultivars. Ingestibility was positively correlated with the lamina to pseudostem ratio, while digestibility was negatively correlated with the quantity of dead leaves in the fresh forage. No correlations were found between the intake under grazing and ingestibility, in vivo dige stibility and palatability measured with the housed animals. The poten tial value of perennial ryegrass cultivars under grazing can not be dr awn from the feeding value assessment with housed animals. Green lamin a mass could be a good trait to assess in an evaluation process of gra ss cultivars and to select for since it seems to be related to the pot ential intake by grazing sheep at a given management. ((C) Elsevier/In ra).