To investiga te the influence of reticulo-ruminal movements on dry matter disappearance (DMD) of tropical grass in the rumen of goat, an experiment measuring DMD of leaf and stem of Rhodes grass (Chloris gayana) was conducted using nylon bag in the rumen of goat or in vitro incubation with rumen fluid of the goat. DMD in the rumen in 48 hr was measured with chopped (about 3 cm in length) materials and in vitro DMD in 48 hr was measured with chopped and ground (1 mm) materials. The authors regarded DMD of chopped materials in the rumen as DMD with reticulo・ruminalmovements and in vitro DMD of chopped materials as DMD without reticulo・ruminal movements. In addition, comparing in vitro DMD of chopped materials with that of ground materials, the authors discussed the effect of mastication on DMD of mature tropical grasses. The resuIts obtained were as follows: 1. There was little difference between DMD of chopped materials in the rumen and that with in vitro incubation. Therefore, reticulo・ruminal movements seemed not to play an important role in DMD of chopped materials of Rhodes grass in the rumen of goat. 2. In vitro DMD of ground materials was higher than that of chopped materials. The difference in DMD between ground and chopped materials became larger with the increase of lignin content of the materials,and the result supported the effect of mastication on DMD of mature tropical grasses.
本研究は, 境地型イネ科牧草のローズグラスを用い,山羊籍二胃内での細切試料(長さ約3cm)の乾物消失に対する反芻胃運動の影響を追究したものである.また,粉砕試料(1mm) と細切試料との第一冒液による in vitro 乾物消失率を比較し, 粉砕の効果をリグニン含量との関連で検討し,反芻そしゃくが乾物消失におよぼす影響についても考察した.得られた結果は次のとおりである.1. ローズグラス細切試料について,節一胃内48時間放置による乾物消失率と,第一胃液を用いた39℃,48時間の in vitro 培養による乾物消失率とでは,同様の値が示された.したがって,細切試料の第一胃内乾物消失に対しては,反芻胃運動それ自体はほとんど影響をおよぼさないことが推察された.2. ローズグラスの粉砕試料と細切試料とについて,第一胃液を用い,39℃,48時間の in vitro 培養を行った場合,いずれの試料についても,細切試料より粉砕試料で乾物消失率は高くなった.また,両試料間の乾物消失率の差は, リグニン含量の増加に伴い増大し,反芻によるそしゃくの役割の大きいことが示された.