Abstract
This trial was carried out to clarify the composition and the rate of disappearance of neutral detergent fiber of the stem and sheath, and the leaf of soiling sorgo forage and Italian ryegrass hay by the in vivo and the in vitro method. The results obtained were summarized as follows. 1. There were little differences in neutral detergent fiber (NDF) contents of the three forages, but the apparent digestibilities of NDF of the stem and sheath, the leaf of sorgo forage and Italian ryegrass hay were 51.7%, 67.9% and 82.0%, respectively. Therefore, the apparent digestibility of cell contents of Italian ryegrass hay was very low, and lower than that of the stem and sheath of sorgo forage. If the digestibilities of cell contents of the three forages were all 98%, the digestibilities of NDF of the stem and sheath, the leaf of sorgo forage and Italian ryegrass. hay were 36%, 46% and 58%, respectively. 2. There was an increase in NDF, ADF and lignin content of the stem and sheath, and the leaf with growing, except NDF content of the leaf almost remained constant. 3. After 60 hours in the rumen, the rates of disappearance of dry matter of the three forages coincided with each dry matter digestibilities by the total feces collection method. But the rates of disappearance of dry matter of the three were nearly equal to those of each NDF, therefore, those of NDF were very different from the digestibilities of NDF by the total feces collection method. 4. The rate of disappearance of NDF after 72 hours incubation coincided with the digestibility of NDF by the total feces collection method. Also the rates of disappearance of individual NDF were definitely different in the order shown below. Italian ryegrass, the leaf, the stem and sheath of sorgo forage The rates of disappearance of dry matter and NDF of the feces were much lower than those of the forages. 5. Comparing NDF with NDF removed lignin, the rate of disappearance of the latter was higher than that of the former by the in vitro method. Especially, in the case of the feces of the stem and sheath, the rate of disappearance of the NDF removed lignin was nearly two times greater than that of the NDF.
