Quality of the Dichanthium ischaemum (L.) Roberty species on harvesting phenophases

Abstract

The forage value of the species is strongly influenced by their growth stage when they are harvested or grazed. The forage value is the highest during the vegetative growth and the lowest during the seed formation stage. Therefore, when forage species are cultivated for the purpose of feeding cattle, they must be harvested or grazed in the early stages of maturity. As the forage plants reach maturity crude protein content decreases, ADF, NDF content increases and feed digestibility is reduced. The objectives of this study were to determine the influence of harvesting phenophases and of the organo-mineral fertilization on the quality of the Dichanthium ischaemum (L.) Roberty species. The experimental factors were represented by the harvesting phenophase, with three graduations: a1 - harvesting at plants height of 15-18 cm, a2 - harvesting at the ear formation (control), a3 - harvesting to full flowering and fertilization with seven graduations: b1 - unfertilized (control), b2 - N50P50 kg·ha-1 annually, b3 - N75P75 kg·ha-1 annually, b4 - N100P100 kg·ha-1 annually, b5 - 10 Mg·ha-1 sheep manure annually, b6 - 20 Mg·ha-1 annually and b7 - 30 Mg·ha-1 annually sheep manure applied at two years. The obtained results showed that the developmental stage is an essential factor that determines important changes in the quality of the analyzed species, the chemical composition of the species obtained being influenced by the harvesting phenophase, as well as the type of fertilizer and the applied doses. The relative qualitative value of the forage was found to be highest during the vegetative growth, so as the species advances the vegetation the crude protein content decreases, the content in ADF, NDF increases and its digestibility decreases.