Variation in cell wall digestibility of perennial ryegrass at heading stage

Perennial ryegrass (Lolium perenne) is the dominant forage grass in Europe, be-cause of its high protein content and energy value. As high levels of water soluble carbohydrates (WSC) lead to rumen acidosis, the energy contained within the cell walls, which is released more gradually, has become a focus in ryegrass breeding. We have assessed the cell wall digestibility (NDFD) of blade, sheath and stem fraction of a set of 13 genotypes harvested at heading stage. Significant genotype-to-genotype differences have been found for total plant NDFD, be it limited. For sheath and stem, the observed variation in NDFD is higher than for the total plant and were shown to significantly affect plant NDFD. Further, also the weight fraction of leaf has an impact on the total plant NDFD values. Studying this limited set of genotypes revealed limited variation in NDFD at the plant level, but a significant variation in organ fractions and organ-specific NDFD values, indicating potential selection targets to improve cell wall digestibility at the whole plant level.