摘要
The objective of this trial was to study the effects of different dietary levels of crude protein (CP) on intake and apparent total tract, intestinal, and ruminal digestibilities of nutrients in Holstein x Zebu steers. The diets contained [dry matter (DM) basis]: 10.5, 12, 13.5, or 15% of CP and a forage (Tifton 85):concentrate ratio of 65:35. Four castrated animals averaging 487.3 kg of body weight at the beginning of the trial and fitted with both abomasum and rumen cannulas were randomly assigned to a 4 x 4 Latin square. Each experimental period lasted 20 days with 10 days for diet adaptation and 10 days for sample collection (feces, abomasum digesta, ruminal content, and urine). Chromium oxide was used as the external marker for determination of fecal excretion. Increasing dietary levels of CP did not change significantly the intakes of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and total digestible nutrients (TDN). However, intake of CP increased while that of ether extract (EE) and non-fiber carbohydrate (NFC) decreased with the increment of dietary CP. Apparent total tract digestibilities of DM, OM, and CP all increased linearly by increasing the dietary CP from 10.5 to 15%. Except for intestinal digestibility of CP that increased 2.77 percentage units for each 1% increment in the diet CP, the different dietary CP levels did not affect intestinal and ruminal digestibilities of all remaining nutrients in the current trial.
摘要译文
这项试验的目的是研究粗蛋白质（CP）的摄入量和表观总肠道，肠道不同的饮食水平的影响，在荷斯坦营养物质的消化率瘤胃咋不X公牛。饮食中包含[干物质（DM）的基础上]：CP 10.5，12，13.5，或15％和饲料（85蒂夫顿）：集中的65:35比例。四阉割动物的平均487.3千克体重在审判的开始，并配有两种皱胃和瘤胃套管被随机分配到一个4×4拉丁方。每个实验期间持续了20天，10天为饮食适应和10天的样品收集（粪便，皱胃食糜，瘤胃内容，和尿）。氧化铬被用作外部标记测定粪便排泄的。增加的CP膳食水平没有改变的干物质（DM），有机物（OM）显著的摄入量，中性洗涤纤维（NDF）和总可消化养分（TDN）。然而，摄入的CP增加而粗脂肪（EE）和非纤维碳水化合物（NFC）的下降与饮食CP的增量。 DM，OM的表观总肠道消化率，和CP全部由饮食CP增加10.5％至15％呈线性增加。除了用于CP的肠消化率，在饮食中的CP增加到2.77个单位的每1％的增量，不同的日粮中粗蛋白水平没有影响到当前试验的所有剩余营养物质小肠和瘤胃消化率。
CAVALCANTE, Maria Andréa Borges. Crude protein levels in diets of beef cattle: intake and apparent total tract, intestinal, and ruminal digestibilities of nutrients[J]. Revista Brasileira de Zootecnia, 2005,34(6 suppl): 2200-2208