Seasonal changes in the digestion and passage rates of fresh dwarf bamboo (Pleioblastus argenteostriatus f. glaber) in sheep

The aim of this study was to determine and characterize the ruminal degradability and passage rate of fresh dwarf bamboo (Pleioblastus argenteostriatus f. glaber) cut in spring and autumn, to study the influence of these variables on intake and digestibility by sheep. The experiment was conducted in late spring (May to early June) and autumn (late September to early October). Eight Suffolk ewes, surgically fitted with ruminal cannulae, were used to measure the ruminal degradability and passage rate. Half of the animals received fresh dwarf bamboo and the other half fresh bahiagrass twice daily to meet maintenance requirements. In spring, the lignin content of dwarf bamboo was similar to that of bahiagrass and approximately twice that of bahiagrass in autumn. The slowly degradable fraction of dry matter (DM) and neutral detergent fiber (NDFom) was lower in dwarf bamboo than in bahiagrass. This fraction decreased in dwarf bamboo in the autumn, in contrast to bahiagrass which maintained similar levels as in the spring (Grass × Season interaction; P=0.005 and 0.016 for DM and NDFom, respectively). However, no difference was observed in degradation rate between grasses and seasons. The degradation rate of crude protein (CP) in dwarf bamboo was lower than that of bahiagrass, particularly in autumn. The ruminal passage rate was unaltered by the type of grass and season. DM intake was similar between the grasses, although a seasonal decrease was observed in both the grasses (P=0.006). The digestibility of DM and NDFom were clearly lower in dwarf bamboo than in bahiagrass (P