放牧山羊

To investigate the effect of growing stages of Rhodes grass (17, 27, 40, 54, 79 and 108 days of regrowth) on ingestive behaviour of grazing goats, an experiment measuring chemical composition and in vitro organic matter digestibility of harvested and unharvested parts of the herbage was conducted using two oesophageal fistulated female goats. Organic matter intake per bite (OMI/TB) and digestible organic matter intake per bite (DOMI/TB) by the goats was also estimated. In addition the relation between organic matter intake per harvesting bite (OMI/HB) and mastication bites per harvesting bite (MB/HB) was discussed. The results obtained were as follows: 1. Grazing goats tended to harvest the part of higher crude protein content and lower cell wall constituents of Rhodes grass, and also tended to harvest the part of higher organic matter digestibility of the herbage. 2. Until 54 days of regrowth (booting stage) OMI/TB and DOMI/TB increased and showed maximum value of 0.025g and 0.017g respectively, and decreased afterwards. 3. Concerning OMI/HB, it markedly increased until 54 days of regrowth and gradually decreased afterwards. Though MB/HB tended to increase until 79 days of regrowth (heading stage), it showed little change between 79 and 108 days of regrowth. The authors suggested that these results were mainly caused by the progress of lignification in Rhodes grass. From the results of this experiment, grazing goats tended to show selective grazing on Rhodes grass pasture and their ingestive behaviour was affected by growing stages of the herbage.