Ferreira et al., 2018. Pesq. Agropec. Trop., 48(3): 245-253

ABSTRACT With the advancement of the cutting age, there is an increase in the forage yield of elephant grass (Pennisetum purpureum), but there is also a reduction of the protein levels and digestibility of this forage. This study aimed to identify the ideal cutting age of elephant grass forage (BRS Canará cultivar) to chopped hay production. The experimental design was a randomized block, with five treatments (42, 60, 76, 91 and 105 days of growing) and four replicates. Forage agronomical, morphological and chemical characteristics were evaluated. A linear positive effect of the cutting age was observed on plant height, senescent material and yield of the chopped hay. The leaf percentage and leaf:stem ratio were reduced by the advance in the cutting age. There was also a linear positive effect of the cutting ages on indigestible neutral detergent fiber, neutral detergent fiber corrected for ash and protein and neutral detergent insoluble protein, with increases of 17.13 %, 16.63 % and 20.66 %, respectively. The contents of ashes, crude protein, total digestible nutrients and net lactation energy were reduced with the advance in the forage age. From 76 days, the ashes contents reached values below 9.29 % and the crude protein below 7.16 %. In the same cutting age, the chopped hay yield was 12.91 t ha-1. To improve the hay quality and production, the BRS Canará cultivar must be harvest between 60 and 76 days, when the plants are with 1.20-1.50 m of height, leaf:stem ratio of 0.55-0.44, crude protein of 8.29-7.16 % and indigestible neutral detergent fiber of 26.21-29.06 %.