Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA.
J Anim Sci. 2013 Jan;91(1):203-10. doi: 10.2527/jas.2010-3776. Epub 2012 Oct 9.
Two experiments were conducted to compare values for the standardized total tract digestibility (STTD) and the relative bioavailability of P in dicalcium phosphate (DCP) and distillers dried grains with solubles (DDGS) when fed to growing pigs. In Exp. 1, the apparent total tract digestibility (ATTD), the basal endogenous P loss (EPL), and the STTD of P in DCP and DDGS were determined. Eighteen pigs (initial BW: 34.93±1.04 kg) were allotted to 3 cornstarch-based diets in a randomized complete block design and housed individually in metabolism cages. Two diets contained DCP and DDGS, respectively, as the sole source of P and the last diet was a P-free diet that was used to measure EPL from the pigs. Results indicated that the ATTD of P in DCP and DDGS were 86.1 and 58.8%, respectively, and the STTD of P in DCP and DDGS were 93.1 and 63.1%, respectively. The EPL was determined at 174 mg/kg DMI. In Exp. 2, 42 pigs (initial BW: 29.02±2.03 kg) were allotted to 7 dietary treatments in a randomized complete block design. Pigs were housed individually and allowed ad libitum access to feed and water. A basal diet (0.22% P) based on corn, casein, cornstarch, and potato protein concentrate was formulated. Three additional diets were formulated by adding 0.04, 0.08, or 0.12% P from DCP to the basal diet to create diets containing 0.26, 0.30, or 0.34% P. The last 3 diets were formulated by adding 0.04, 0.08, or 0.12% P from DDGS to the basal diet at the expense of cornstarch. Pigs were fed experimental diets for 28 d. They were then euthanized and the third and fourth metacarpals from the right front foot were collected. Metacarpal bone ash and bone P were regressed against P intake for each ingredient and via slope ratio methodology, it was determined that the bioavailability of P in DDGS was 87% relative to that in DCP. It was concluded from this work that the value for relative bioavailability of P in DDGS overestimates the digestibility of P in DDGS and values for the STTD of P, therefore, can not be accurately calculated from values for the relative bioavailability of P. As a consequence, it is necessary to determine the STTD of P in feed ingredients included in diets fed to pigs.
进行了两项实验来比较在生长猪饲粮中使用磷酸二钙（DCP）和玉米DDGS 时，标准化总肠道消化率（STTD）和磷相对生物利用率（P 的 RBV）的值。在实验 1 中，测定了 DCP 和 DDGS 的表观总肠道消化率（ATTD）、基础内源磷损失（EPL）和 DCP 和 DDGS 中磷的 STTD。18 头猪（初始 BW：34.93±1.04kg）按随机完全区组设计分配到 3 种基于玉米淀粉的饲粮中，并单独饲养在代谢笼中。两种饲粮分别以 DCP 和 DDGS 为唯一磷源，最后一种饲粮为无磷饲粮，用于测定猪的 EPL。结果表明，DCP 和 DDGS 中磷的 ATTD 分别为 86.1%和 58.8%，DCP 和 DDGS 中磷的 STTD 分别为 93.1%和 63.1%。EPL 为 174mg/kgDMI。在实验 2 中，42 头猪（初始 BW：29.02±2.03kg）按随机完全区组设计分配到 7 种饲粮处理。猪单独饲养，自由采食和饮水。配制了一种基于玉米、酪蛋白、玉米淀粉和马铃薯蛋白浓缩物的基础饲粮（含磷 0.22%）。通过在基础饲粮中添加 0.04%、0.08%或 0.12%的 DCP 来自 DCP 来配制另外 3 种饲粮，以创建含磷 0.26%、0.30%或 0.34%的饲粮。最后 3 种饲粮通过用 DDGS 代替基础饲粮中的玉米淀粉来添加 0.04%、0.08%或 0.12%的磷来配制。猪饲喂试验饲粮 28d。然后将它们安乐死，从右前脚的第三和第四掌骨中采集。通过回归分析第三和第四掌骨灰分和骨磷与每种原料的磷摄入量之间的关系，并通过斜率比方法，确定 DDGS 中磷的 RBV 相对 DCP 中磷的生物利用率为 87%。从这项工作中得出结论，DDGS 中磷的相对生物利用率的值高估了 DDGS 中磷的消化率，并且不能从磷的相对生物利用率值准确计算 STTD 值。因此，有必要确定饲粮中包含的饲料原料的磷 STTD 值。
