Space use, herbage selection, and animal performance of grazing heifers on a peaty river valley section

Grazing is a suitable option for managing the habitat functions of restored fen grasslands. Nevertheless, nutritional requirements of the grazing livestock need to be considered to make such grazing systems sustainable. In order to analyze the interactions between the development of forage nutritive values, grazing behaviour and resulting liveweight gains, we implemented a grazing experiment at a typical river valley section in Northeast-Germany. We tested the hypothesis that heifers were able to compensate the decreasing digestibility of pasture growth over the course of the grazing period by selective grazing. Herbage on offer and faeces of heifers were sampled and analyzed biweekly from May to October over three grazing seasons. The nitrogen content of the faeces was used to estimate the digestibility of the selected herbage. The sedge-dominated peat area was not used for grazing before the grass-dominated sections of the moraine area were depleted, despite acceptable energy contents of the sedge-dominated plant communities during spring and early summer. This behaviour limited the degree of energy selection. The energy content of the herbage on offer explained 67% of the variations in daily liveweight gain. Results indicate the need to modify the management of continuous stocking systems for achieving economically feasible gains