Effect of cutting height and stage of development on lucerne quality in the Po plain

To improve pre-harvest forage quality of lucerne an increase of the cutting height was studied under two high quality cutting schedules in a two year experiment. Two different harvest schedules (VB, first cut at late vegetative and following cuts at bud stage; VF, first cut at late vegetative and following cuts at early flowering) and two cutting height (4 and 14 cm) were compared to evaluate dry matter (DM) yield, morphological stage of development, crude protein (CP), NDF, ADL, and enzymatic organic matter digestibility (OMD). The stratified quality was analysed in six canopy segments for a summer cut. Increasing the cutting height improved the protein and digestibility contents in both schedules without compromising the stand persistence. In the VB schedule the increase in the cutting height resulted in an NDF that was lower than 370 g kg-1 DM, while the OMD were always higher than 700 g kg-1 OM, both considered as threshold values for quality purposes. The OMD of the bottom parts of stem remained almost constant till 22 cm with values of 470 and 400 g kg-1 OM for VB and VF, respectively. Leaves showed a constant quality with a CP content of 318 g kg-1 DM and OMD of 769 g kg-1 OM. The increase in the cutting height leads to relevant improvement in the forage quality when performed at vegetative and early bud stages, while on more mature forages the increase in the height of cut proved to be a valuable method to increase forage quality only when performed over 20 cm.