Nutritive Value of Feed Evaluated by Net Flux of Nutrient in Portal-Drained Viscera

本研究旨在利用反刍动物门引流器官的净营养通量来评价饲料的营养价值。5头小牛将导管植入门静脉、肠系膜静脉和动脉中，其中2头小牛有十二指肠插管。它们被喂食七种饮食：基础饮食（10%CP）由30%组成。干草和70%精料，和其他添加鱼粉（FM）或豆粕（SBM）在三个水平，等氮。犊牛（BW：83 ~ 281 kg）每12 h给予能量维持需要。每天分别取十二指肠内容物6次和血液12次。作为指示剂，氧化铬用于十二指肠流量，对氨基马尿酸用于血流量。通过回归分析得到的结果如下。1.所有日粮经PDV释放的α-氨基氮（AAN）平均有35.1%进入十二指肠。2.氨态氮的释放量分别为34.8%和29.9%，尿素氮的吸收量分别为18.2%和7.5%。3. AAN的释放量与日粮氮含量呈二次回归关系（R2=0.99），且在较高的氮含量下，FM的峰值大于SBM。4. SBM的葡萄糖吸收倾向于大于FM。这些新的认识意味着反刍动物蛋白质营养的传统观念必须改变，基于PDV净养分通量的饲料营养价值评价可能比基于消化率的饲料营养价值评价更可靠。

The objective of this study was to evaluate the nutritive value of feed with net flux of nutrient by portal-drained viscera in ruminants. Five calves implanted catheters into the portal vein, the messenteric vein and the artery was used, and two of them had the duodenal cannula. They were fed seven diets: a basal diet (10% CP) consisted of 30%. hay and 70%, concentrate, and others were supplemented fish meal (FM) or soybean meal (SBM) at three levels, isonitrogenously. The calves (BW : 83 to 281 kg) were given the maintenance requirement of energy every 12 h. The samples of duodenal contents and bloods were taken 6 times and 12 times daily, respectively. As an indicator, chromic oxide was used for the duodenal flow, and p-aminohippurate was for blood flow. The obtained results by regression analysis were as follows. 1. α-amino nitrogen (AAN) release by PDV for all diets averaged 35.1% of nonammonia N entered the duodenum. 2. Ammonia N release by PDV of N intake was 34.8% for FM and 29.9% for SBM, and urea N uptake was 18.2% and 7.5%, respectively. 3. AAN release in response to the dietary N content conformed to quadratic regression (R2=0.99), and the peak value for FM compared with SBM was greater at a higher dietary N content. 4. Glucose absorption tended to be greater for SBM than for FM. These new knowledge imply that the usual concept on ruminant protein nutrition must be changed, and that the evaluation for feed nutritive values based on net nutrient flux by PDV is probably more reliable than on the digestion.