Regmi P R, Sauer W C, Zijlstra R T
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
J Anim Sci. 2008 Oct;86(10):2619-26. doi: 10.2527/jas.2008-1058. Epub 2008 Jun 20.
The DE content within cereal grains can vary 25% mainly due to changes in apparent total tract digestibility (ATTD) of energy. In vitro digestibility techniques have been developed to predict the DE value among feedstuffs. However, these techniques have not been tested properly for their suitability to predict the variation in energy digestibility and DE content within a cereal grain. The objective of the present study was to establish and evaluate an in vitro digestibility technique to predict in vivo ATTD of energy of barley in grower pigs. Barley grain samples (hulled, n = 21) with a large range in quality were collected; the ADF and CP content ranged from 4.5 to 11.4% and 10.0 to 16.4% (DM basis), respectively. The ATTD of energy was determined using barrows (n = 63, 33 +/- 2.1 kg of initial BW) in 2 periods with 6 observations per sample and ranged from 51.9 to 78.5%, with relative errors between 0.4 and 5.0%. A preliminary study, comparing a 2- and a 3-step in vitro digestibility technique using 3 barley samples, indicated that R(2) between in vivo and in vitro energy digestibility was greater using the 3- than the 2-step technique (0.92 vs. 0.76). Therefore, the 3-step in vitro digestibility technique was used solely in subsequent analyses. Briefly, ground barley was subsequently incubated with pepsin for 6 h, pancreatin for 18 h, and cellulase for 24 h. The DM and GE content of samples and residues were measured to calculate digestibility. The in vitro energy digestibility of the 21 barley samples with duplicate measurements ranged from 63.7 to 82.2%, with relative errors between 0.1 and 2.6%. In vitro energy digestibility was strongly related (y = 1.25 x - 25.22; R(2) = 0.81) to in vivo energy digestibility. Finally, a subset of 7 barley samples was analyzed in quadruplicate using the 3-step in vitro technique. The relationship between in vitro and in vivo energy digestibility was very strong (y = 1.23 x - 25.33; R(2) = 0.97) with relative errors between 0.5 and 2.7%. In vitro DE and energy digestibility were perfectly related (R(2) = 1.00). In summary, the 3-step in vitro energy digestibility technique can accurately predict the ATTD of energy in barley in grower pigs. The 3-step in vitro digestibility technique, thus, might be useful as the reference laboratory procedure to calibrate analytical equipment to rapidly predict the ATTD of energy in barley.
谷物中的消化能（DE）含量可能会有25%的变化，这主要是由于能量的表观全肠道消化率（ATTD）发生了改变。已开发出体外消化率技术来预测饲料原料中的DE值。然而，这些技术在预测谷物中能量消化率和DE含量变化的适用性方面尚未得到充分测试。本研究的目的是建立并评估一种体外消化率技术，以预测生长猪体内大麦能量的ATTD。收集了质量范围广泛的大麦籽粒样本（去壳，n = 21）；酸性洗涤纤维（ADF）和粗蛋白（CP）含量分别为4.5%至11.4%和10.0%至16.4%（干物质基础）。使用小公猪（n = 63，初始体重33±2.1千克）在两个阶段测定能量的ATTD，每个样本进行6次观测，范围为51.9%至78.5%，相对误差在0.4%至5.0%之间。一项初步研究比较了使用3个大麦样本的两步和三步体外消化率技术，结果表明，三步技术在体内和体外能量消化率之间的R²值（0.92）大于两步技术（0.76）。因此，在后续分析中仅使用了三步体外消化率技术。简要来说，将磨碎的大麦随后与胃蛋白酶孵育6小时、胰蛋白酶孵育18小时、纤维素酶孵育24小时。测量样本和残渣的干物质和总能含量以计算消化率。对21个大麦样本进行重复测量，其体外能量消化率范围为63.7%至82.2%，相对误差在0.1%至2.6%之间。体外能量消化率与体内能量消化率密切相关（y = 1.25x - 25.22；R² = 0.81）。最后，使用三步体外技术对7个大麦样本的子集进行了四次重复分析。体外和体内能量消化率之间存在非常强的关系（y = 1.23x - 25.33；R² = 0.97），相对误差在0.5%至2.7%之间。体外DE与能量消化率完全相关（R² = 1.00）。总之，三步体外能量消化率技术可以准确预测生长猪体内大麦能量的ATTD。因此，三步体外消化率技术可能作为参考实验室程序，用于校准分析设备以快速预测大麦中的能量ATTD。
