Faculty of Life and Environmental Science, Shimane University, Matsue, Japan.
Anim Sci J. 2009 Aug;80(4):387-97. doi: 10.1111/j.1740-0929.2009.00654.x.
The aim of this experiment was to examine the effect of rumen digesta flow parameters on effective degradability (EDG) and microbial nitrogen (MBN) yield in sheep fed diets of identical provision of both metabolizable energy and rumen degradable nitrogen (RDN). Ruminal degradation parameters of early-harvested perennial ryegrass hay (EH), late-harvested perennial ryegrasses hay (LH) and winter sown barley straw (BS) were determined by a nylon bag technique. Subsequently, three experimental diets (EHD, LHD and BSD) were formulated using the tested forages, sucrose and urea as supplements. An in vivo feeding study was conducted using four rumen cannulated sheep in a partial Latin square design. Digestibility, rate constants of rumen particle breakdown and passage, ruminal fermentation parameters and MBN supply to the small intestine were determined. Animals thoroughly consumed the forages fed at a restricted level. Digestion coefficients were greater for EHD than for LHD and were lowest for BSD (P < 0.05). The rate constant of large particle breakdown was 4.3, 5.9 and 6.7 %/h, respectively, and small particle passage was 5.3, 4.7 and 6.3 %/h for EHD, LHD and BSD, respectively. The estimates differed (P < 0.05) between the diets. The overall passage rate constant of total rumen particles was estimated to be higher for BSD than that for EHD or LHD (P < 0.05). Ruminal fermentation parameters were unaffected by dietary treatments (P > 0.05). Intake levels of rumen degradable organic matter (RDOM) and RDN were estimated to be greater for LHD than that for EHD or BSD (P < 0.05). Although dietary arrangements were made to give identical microbial efficiency, the estimated value was higher for EHD than that for LHD or BSD (P < 0.05); and the MBN yield for BSD was estimated to be lower than that for EHD or LHD (P < 0.05). Rumen kinetic parameters of degradation and particle flow of forage affected EDG values and MBN yield from forage-related RDN intake, although those had little effect on the efficiency of MBN yield from forage-related RDOM intake.
本实验旨在研究瘤胃液流量参数对绵羊采食代谢能和瘤胃可降解氮（RDN）供给量相同的饲粮时有效降解率（EDG）和微生物氮（MBN）产量的影响。采用尼龙袋技术测定了早收黑麦草干草（EH）、晚收黑麦草干草（LH）和冬播大麦秸秆（BS）的瘤胃降解参数。随后，使用这些饲草、蔗糖和尿素作为补充物，配制了三种实验饲粮（EHD、LHD 和 BSD）。采用 4 只瘤胃瘘管绵羊进行部分拉丁方设计的体内饲喂研究。测定了消化率、瘤胃颗粒分解和通过的速率常数、瘤胃发酵参数和 MBN 向小肠的供应。动物在限制水平下充分采食饲粮。EHD 的消化系数大于 LHD，BSD 最低（P < 0.05）。大颗粒分解的速率常数分别为 4.3%/h、5.9%/h 和 6.7%/h，小颗粒通过的速率常数分别为 5.3%/h、4.7%/h 和 6.3%/h，EHD、LHD 和 BSD 之间存在差异（P < 0.05）。总瘤胃颗粒的总体通过速率常数估计 BSD 高于 EHD 或 LHD（P < 0.05）。饲粮处理对瘤胃发酵参数没有影响（P > 0.05）。LHD 的瘤胃可降解有机物质（RDOM）和 RDN 摄入量估计高于 EHD 或 BSD（P < 0.05）。尽管日粮安排使微生物效率相同，但 EHD 的估计值高于 LHD 或 BSD（P < 0.05）；BSD 的 MBN 产量估计低于 EHD 或 LHD（P < 0.05）。饲草降解和颗粒流动的瘤胃动力学参数影响了 EDG 值和饲草相关 RDN 摄入的 MBN 产量，但对饲草相关 RDOM 摄入的 MBN 产量效率影响很小。
