The effect of previous contrasting grazing intensity on the content of nutrients in pasture forage

摘要

The mineral concentration in herbage is one of the key factors that determine its quality. The aims of the study was to determine the optimal period for grazing and the optimal term for hay harvest in relation to the nutrient requirements of cattle and to determine the dynamics of forage yield and mineral concentration during the vegetation season. Besides seasonal development, intensive or extensive grazing treatments applied in the previous grazing seasons significantly affected the mineral concentrations and biomass yields. At the beginning of the vegetation season the concentrations of N, Ca and Mg in the forage were higher in the previously intensively grazed plots than in extensively grazed ones. However, in the course of vegetation season thedifferences between these two treatments were not significant. Because of low K concentrations and high Ca and Mg concentrations in the forage there was no problem with tetanus ratio (K/(Ca+Mg)). The present work shows that the optimal period for harvest in relation to yield and mineral concentration in the herbage is from mid-May to mid-June in an upland Central European grasslands. After this period changes were revealed in the concentrations of the minerals, which significantly deteriorated the forage quality.