二元线性回归法测定生长猪内源磷排泄量及麦麸和豆粕磷的真消化率

本研究采用二元线性回归法测定生长猪内源磷排泄量及麦麸和豆粕磷的真消化率.选用6头健康大白×长白阉公猪为试验动物,平均体重为(34.42±0.64)kg.采用6×6拉丁方设计,设6个总磷水平(0.12%、0.25%、0.28%、0.35%、0.47%和0.54%),日粮以豆粕、葡萄糖、玉米淀粉等为基础原料,麦麸和豆粕为磷来源.日粮中添加0.1%TiO2作为外源指示剂.试验分6个试验期,每期6 d,4 d适应期,2 d收粪期.结果表明,生长猪粪磷的排出量与日粮磷的摄入量呈线性关系(y=0.515 7x-0.0133,R2=0.97,P<0.01),回归法测得生长猪内源磷的排泄量为0.933 0g/kg,麦麸和豆粕磷的真消化率分别为48.07%和47.50%.分析粪磷来源发现,内源磷排泄量基本不变(P>0.05),而粪磷随日粮磷含量的增加而极显著增加(P<0.01).由结果可知,线性回归法可用于测定猪内源磷排泄量及麦麸和豆粕磷的真消化率.     

多重线性回归法测定猪内源磷排泄量及饲料磷真消化率的研究

本研究采用多重线性回归法测定生长猪内源磷排泄量及花生粕和豆粕磷的真消化率。选用6头健康大白×长白阉公猪为试验动物,平均体重为(24.8±1.42)kg。采用6×6拉丁方设计,设6个磷水平(0.09%、0.17%、0.26%、0.35%、0.43%、0.53%),以豆粕、葡萄糖、玉米淀粉等为基础,以花生粕为待测植物性饲料,配制半纯合试验日粮,花生粕和豆粕为磷唯一来源。日粮中添加0.35%Cr2O3作为外源指示剂。试验分6个试验期,每期8 d,6d适应期,2 d收粪期。结果表明,在以g/kg DMI为计量单位条件下,生长猪粪磷的排出量与日粮磷的摄入量呈线性关系(P=0.000 1),回归法测得生长猪内源磷的排泄量为0.526 6 g/kg DMI,花生粕磷的真消化率为28.00%,豆粕磷的真消化率为38.87%。分析粪磷来源发现,内源磷排泄量基本不变(P=0.13),而日粮来源粪磷随日粮含量的增加而增加(P=0.000 1),说明多重线性回归法可用于测定猪内源磷排泄量及非常规植物性饲料磷的真消化率;比较真消化率和表观消化率值说明,真消化率比表观消化率具有较好的重复性。     

多重线性回归法测定猪内源磷排泄量及饲料磷真消化率的研究

本研究旨在采用多重线性回归法测定生长猪内源磷排泄量及高粱和豆粕中磷的真消化率。试验选用6头健康大白×长白阉公猪为消化试验动物,平均体重为(23.6±1.23)kg。采用6×6拉丁方设计,设6个磷水平(0.08%、0.15%、0.23%、0.30%、0.38%、0.53%),以豆粕、葡萄糖、玉米淀粉等为基础,以高粱和豆粕为磷唯一来源,配制半纯合试验饲粮。饲粮中添加0.35%Cr2O3作为外源指示剂。试验分6个试验期,每期8d,其中6d适应期,2d收粪期。饲粮中磷表观消化率受饲粮中磷水平的影响(P<0.05),并随饲粮中磷水平的提高由14.88%增大至34.88%。在以g/kgDMI为计量单位条件下,生长猪粪磷的排出量与饲粮磷的摄入量呈线性关系(P=0.0001)。结果表明,多重线性回归法可用于生长猪内源磷排泄量和植物性饲料磷真消化率的测定;以豆粕-高粱型模型饲粮测定出生长猪内源磷排泄量为0.2940g/kgDMI,高粱中磷的真消化率为56.05%,豆粕中磷的真消化率为39.41%。     

用线性回归法测定生长母猪内源钙、磷排泄量和豆粕钙、磷真消化率的研究

本文旨在用线性回归法(又称梯度回归法,regression analysis technique,REG)测定生长母猪钙、磷内源排泄和豆粕钙、磷真消化率。选择6头大白×长白二元杂交生长母猪,平均初始体重为(27.6±3.0)kg。采用6×6拉丁方设计,以玉米淀粉-豆粕为基础配制6个不同钙(0.04%、0.09%、0.13%、0.17%、0.22%和0.26%)和磷(0.09%、0.18%、0.27%、0.35%、0.44%和0.53%)水平的半纯合日粮,试验共6期,每期8d,预试期6d,正试期2d。结果得出,以日粮干物质采食量(DMI)为基础,粪钙的排泄量随日粮钙摄入量的增加而线性增加(P<0.01),用回归曲线法得出内源钙排泄量为0.43g/kg DMI,豆粕钙的真消化率为23.41%。以DMI为基础,粪磷总排泄量随日粮磷摄入量的增加而线性增加(P<0.01),内源磷排泄量为0.89g/kg DMI,豆粕磷真消化率为41.44%。钙平均表观消化率比真消化率低28.77%,磷平均表观消化率比真消化率低29.24%。结果显示,不同钙、磷水平的豆粕日粮,钙、磷的表观消化率变化比较大,而真消化率相对稳定。用表观消化率进行饲料配方,会导致钙、磷生物学效价的低估,造成钙、磷过量添加和猪粪钙、粪磷的增加。用真消化率评定钙、磷的生物学效价,比表观消化率更准确,因此在配制动物日粮时更能接近动物实际生产需要量,既不造成浪费也不会出现缺乏。     

不同方法测定生长猪内源磷排泄量及磷真消化率的比较研究

采用梯度回归法(REG法)和差量法,用豆粕和次粉作为日粮磷唯一来源,分别设计了 2 组总磷(TP)水平为0 .15%、0. 20%、0. 30%、0. 35%梯度饲粮,按4×4拉丁方设计,测定了20 kg生长猪内源磷排泄量和豆粕、次粉磷的真消化率。结果表明,在0 .15%~0 .35%TP水平范围,粪磷的排泄量与磷摄入量之间存在明显的线性关系,动物具有稳定的内源磷排泄量。不同饲料条件下REG法测定的内源磷排泄量与差量法测定结果无显著差异(P>0. 05),2种方法测定内源磷排泄量都是可行的;生长猪内源磷排泄量为0. 65~0. 68 g/kg DMI;次粉磷的真消化率显著高于豆粕(P<0. 01),分别为63.7%和52.1%。     

日粮磷水平对线性回归法测定磷真消化率的影响

本试验旨在研究日粮磷水平对线性回归法测定豆粕中磷真消化率的影响。选用48头平均体重为(36.0±0.1)kg生长公猪,采用2×3因子完全随机区组设计,随机分为6个处理,每个处理8个重复,每个重复1头猪。通过在半纯合日粮(低磷日粮,无玉米添加)和常规日粮(高磷日粮,含50.0%玉米)上添加3个水平豆粕(13.0%、26.0%和39.0%),研究日粮类型(低磷日粮和高磷日粮)对线性回归法测定豆粕中磷真消化率的影响。结果表明:随日粮豆粕水平增加,生长公猪的总磷摄入量、粪磷排泄量、可消化磷和存留磷量呈线性增加(P<0.01)。与低磷日粮相比,采食高磷日粮显著增加日粮总磷摄入量、粪磷排泄量、尿磷排泄量、可消化磷和存留磷(P<0.05)。通过使用线性回归法,生长猪采食高磷日粮测得豆粕中磷的真消化率为36.11%,显著低于采食低磷日粮测得结果 43.38%(P<0.05)。由此可见,由半纯合日粮(低磷日粮)测定得出的豆粕中磷的真消化率显著高于常规日粮(高磷日粮)的测定值,因此在使用半纯合日粮测得饲料原料中磷真消化率的数据用于日粮配置时应考虑上述因素。     

用线性回归法测定生长猪内源钙、磷排泄量和豆粕钙、磷真消化率的研究

用线性回归法（Linear Regression Analysis Technique，REG）测定生长公猪内源钙、磷排泄量和豆粕钙、磷的真消化率。选用6头大白&#215;长白生长阉公猪为试验动物，平均初始体重为（28．6&#177;1．76）kg。采用6&#215;6拉丁方设计，以豆粕-玉米淀粉为基础，配制6个不同钙（0．04％、0．09％、0．13％、0．17％、0．22％、0．26％）、磷（0．09％、0．18％、0．27％、0．35％、0．44％、0．53％）水平的日粮。试验共6期，每期8d，预饲期6d，采样期2d。结果显示，以日粮干物质采食量（DMI）为基础，粪钙的排泄量随日粮钙的摄入量的增加而线性增加（P=0．002〈0．01），通过回归曲线法得出内源钙排泄量为0．6225g／kgDMI，豆粕钙真消化率为44．34％。以日粮干物质采食量（DMI）为基础，粪磷的排泄量随日粮磷的摄人量的增加而线性增加（P=0．025〈0．05），内源磷的排泄量为1．0771g／kgDMI，豆粕磷的真消化率为48．78％。结果表明，不同钙、磷水平的豆粕日粮，钙、磷的表观消化率变化较大，真消化率相对稳定。钙表观消化率平均比真消化率低41．50％，磷表观消化率平均比真消化率低35．51％。日粮配制时用钙、磷表观消化率会低估钙、磷生物学效价，造成钙、磷的过量添加和猪粪钙、粪磷排泄量的增加。因此，日粮配制时用钙、磷真消化率来评定钙、磷的生物学效价更精确。     

饲粮磷水平和采食量对生长猪磷消化率评定的影响

本试验旨在研究饲粮磷水平和采食量对生长猪磷的回肠和全肠道消化率评定的影响。试验选择18头安装简单T型瘘管的生长去势公猪(平均体重35.2 kg)按照9×4不完全拉丁方设计进行消化试验。9个饲粮处理组包含3种饲粮(无磷饲粮、低磷饲粮和高磷饲粮)和3个采食水平(体重的3%、4%和5%)。试验共分4期,每期8 d。结果表明:生长猪回肠食糜磷排泄量和粪磷排泄量随饲粮磷水平的提高极显著增加(P0.01);粪磷排泄量随采食量提高显著增加(P0.05);采食高磷饲粮生长猪磷的表观全肠道消化率(ATTD)随采食量增加线性降低(P0.05),而低磷饲粮组磷的表观回肠消化率(AID)随采食量增加有线性增加的趋势(P0.1);低磷饲粮组磷的标准回肠消化率(SID)随采食量增加有线性增加的趋势(P0.1),而增加采食量有线性降低高磷饲粮组磷的标准全肠道消化率(STTD)的趋势(P0.1)。由此可见,采食量对生长猪磷消化率评定的影响受饲粮磷水平的调控。     

猪日粮有效磷水平对氮磷排放的影响

本研究采用4×4拉丁方设计,选用4头52kg左右的健康三元杂交阉公猪(杜×长×大),以玉米-豆粕型基础日粮(不添加磷酸氢钙,日粮1)为对照,试验日粮分别添加磷酸氢钙0.12%(日粮2)、0.24%(日粮3)和0.36%(日粮4),相应的日粮有效磷(AP)水平分别为0.13%、0.15%、0.17%和0.19%.每期试验12d,预饲期5d,正试期3d,每期试验结束后有4d的恢复期.通过氮、磷平衡试验研究猪对磷、氮的利用率及其对环境的影响.结果表明:日粮1、日粮2、日粮3和日粮4的磷真消化率分别为53.00%、53.78%、65.19%和68.09%;粪磷的排泄量随食入磷量的减少而降低,氮的排泄量与氮表观消化率受日粮磷水平的影响不显著(P＞0.05);综合评价,磷酸氢钙的添加水平为0.12%～0.24%的效果较好,即AP在0.15%～0.17%之间,在不影响猪氮、磷营养需要的条件下,能有效的改善猪排泄物中氮、磷对环境的污染.     

磷的标准全肠道消化率和真消化率评定及其可加性研究

试验旨在比较使用磷的标准全肠道消化率(STTD)和真消化率(TPD)评定生长猪对玉米和豆粕中磷的利用效率及其是否具有可加性。选用56头平均体重为(30.5±0.8)kg的三元杂种去势公猪随机分为7个处理,每个处理8个重复,每个重复1头猪。对照组(无磷饲粮)用于测定猪的内源磷排泄量,6个试验饲粮按2×3因子试验设计,包含2个磷水平(低磷0.14%或高磷0.24%)和3种待测饲料原料(玉米、豆粕以及玉米豆粕混合物)。结果表明,随饲粮磷水平的提高,生长猪总磷日摄入量、粪磷日排泄量和日可消化磷均极显著增加(P0.01)。生长猪采食低磷饲粮和高磷饲粮测得玉米、豆粕以及玉米豆粕混合物中磷标准全肠道消化率(STTD)分别为42.06%和41.11%、48.73%和48.43%、44.38%和44.23%。低磷饲粮和高磷饲粮组玉米豆粕混合物中磷STTD计算值分别为44.28%和43.55%,与测定值44.38%和44.23%相比无显著差异(P0.05)。线性回归法测得玉米、豆粕以及玉米豆粕混合物磷的真消化率(TPD)为40.71%、49.83%和44.21%。玉米豆粕混合物TPD计算值为43.75%,与测定值44.21%相比差异不显著(P0.05)。由此可见,使用磷STTD和TPD用于生长猪玉米豆粕型饲粮配制时均具有较好的可加性。     

Determination of true digestive utilization of phosphorus and the endogenous phosphorus outputs associated with soybean meal for growing pigs

The objectives of this study were to determine true P digestibility, the gastrointestinal endogenous P outputs associated with soybean meal (SBM), and the role of the large intestine in P digestion in growing pigs. Four Yorkshire barrows, with average initial and final BW of 40 and 58 kg, were fitted with a simple T-cannula at the distal ileum and fed four diets according to a 4 x 4 Latin square design. The diets were cornstarch-based and contained four levels of P (0.098, 0.196, 0.293, and 0.391% on a DM basis) from solvent-extracted conventional SBM. Chromic oxide (3.5 g/kg of diet, as-fed basis) was included as a digestibility marker. Each experimental period consisted of 8 d with a 4-d adaptation period and a 4-d collection of representative ileal digesta (2 d) and fecal (2 d) samples. True ileal and fecal P digestibility values and the ileal and fecal endogenous P outputs associated with SBM were determined by the regression analysis technique. There were no differences (P > 0.05) in true P digestibility values (ileal, 59.0 +/- 8.3 vs. fecal, 51.3 +/- 7.9%, n = 16) and endogenous P outputs (ileal, 0.59 +/- 0.18 vs. fecal, 0.45 +/- 0.21 g/kg of DMI, n = 16) between the ileal and the fecal levels. The endogenous fecal P loss accounted for 8.1 and 17.6% of the NRC (1998) recommended total and available P requirements in growing pigs, respectively. In conclusion, approximately 51% of the total P in conventional SBM is digested in growing pigs. The large intestine does not play an important role in the digestion of P associated with SBM in the growing pig. The fecal loss of the gastrointestinal endogenous P is an important route of P excretion in the growing pig.     

生长猪基础饲粮组成对磷酸氢钙和磷酸二氢钙中磷的全肠道真消化率的影响

本试验旨在研究生长猪基础饲粮组成对磷酸氢钙(DCP)和磷酸二氢钙(MCP)中磷的全肠道真消化率(TTTD)的影响。试验1选用10头平均体重为(30.4±1.8)kg的生长猪,按照10×8不完全拉丁方设计,分别饲喂含有5个DCP添加水平的玉米-豆粕型和含有5个DCP添加水平的小麦-豆粕型饲粮,进行8期消化试验;试验2选用10头平均体重为(30.9±1.5)kg的生长猪,按照10×8不完全拉丁方设计,分别饲喂含有5个M CP添加水平的玉米-豆粕型和含有5个MCP添加水平的小麦-豆粕型饲粮,进行8期消化试验。每期消化试验包括5 d的饲粮适应期和2 d的粪便收集期。结果表明:1)玉米-豆粕型饲粮的总粪磷排泄量极显著高于小麦-豆粕型饲粮(P0.01),小麦-豆粕型饲粮的全肠道可消化磷含量和磷的表观全肠道消化率(ATTD)极显著高于玉米-豆粕型饲粮(P0.01)。饲粮添加DCP和MCP线性增加总粪磷排泄量、全肠道可消化磷含量及磷的ATTD(P0.01)。2)通过使用线性回归法,测得生长猪采食玉米-豆粕型和小麦-豆粕型饲粮对DCP中磷的TTTD分别为82.33%和82.88%,生长猪采食玉米-豆粕型和小麦-豆粕型饲粮对MCP中磷的TTTD分别为85.88%和84.62%。由此可见,生长猪基础饲粮组成对DCP和MCP中磷的TTTD无显著影响。     

生长猪饲粮磷水平对磷酸氢钙中磷真消化率评定的影响

本试验旨在研究生长猪饲粮磷水平对磷酸氢钙(DCP)中磷的全肠道真消化率评定的影响。选用56头体重为(25.90±0.25)kg的杜×长×大杂交去势公猪,根据体重随机分为7个处理组,每组8个重复,每个重复1头猪。对照组饲喂未添加DCP的基础饲粮,6个处理组在基础饲粮中分别添加0.64%、1.28%、1.92%、2.56%、3.20%、3.84%DCP。使用全收粪法测定磷的表观全肠道消化率。结果表明:生长猪总磷的表观全肠道消化率随饲粮DCP水平提高呈线性和二次增加(P0.05);随着DCP添加水平的提高,由差量法测得无机磷的全肠道真消化率呈二次上升的趋势(P0.1),具体表现为无机磷的全肠道真消化率随饲粮DCP水平提高呈现出先增加后降低的趋势;通过线性回归法发现,生长猪饲喂低DCP饲粮后测得磷的全肠道真消化率显著高于饲喂高DCP饲粮(P0.05)。由此可见,饲粮磷水平显著影响差量法和线性回归法测得DCP的全肠道真消化率;使用差量法测定饲粮原料磷的全肠道真消化率时应将饲粮磷水平维持在接近磷需要量的水平,使用线性回归法测定磷的全肠道真消化率时应将饲粮磷水平控制在低于磷需要量的范围内。     

Comparison of the regression analysis technique and the substitution method for the determination of true phosphorus digestibility and faecal endogenous phosphorus losses associated with feed ingredients for growing pigs

Two digestibility experiments were carried out to comparatively measure true phosphorus (P) digestibility and the faecal endogenous P loss associated with soybean meal (SBM) and wheat middling meal (WM) for growing pigs by the simple linear regression analysis technique and the substitution method. Eight barrows, with an average initial body weight 21 kg, were randomly divided into two groups of four pigs with each group being fed four test diets according to a 4 × 4 Latin square design. Eight maize starch-based diets containing four levels (on dry matter basis) of P (0.20, 0.24, 0.36 and 0.42%) and P (0.181, 0.26, 0.36, and 0.43%) were formulated from SBM and WM as a sole source of P, respectively. Chromic oxide (0.30%) was used as a digestibility marker. Each experimental period comprised 8 d with a 4-d adaptation and a 4-d collection of faecal samples. Levels of the assay ingredient substitutions had no effects (P > 0.05) on true P digestibility and the endogenous P loss associated with SBM and WM measured by the substitution method. There were no differences (P > 0.05) between the regression technique and the substitution method in measuring the true P digestibility (SBM: 49.4 ± 3.51 vs. 50.6 ± 2.4; WM: 63.7 ± 5.0 vs. 63.2 ± 5.4%) as well as the faecal endogenous P loss (SBM: 0.62 ± 0.10 vs. 0.71 ± 0.11; WM: 0.65 ± 0.16 vs. 0.70 ± 0.17 g/kg dry matter intake) for the growing pig. Thus, true P digestibility and the faecal endogenous P loss in feed ingredients for pigs may be measured by using the regression analysis technique and the substitution method.     

Determination of true ileal amino acid digestibility and the endogenous amino acid outputs associated with barley samples for growing-finishing pigs by the regression analysis technique

This study was conducted to determine true ileal AA digestibility coefficients and the endogenous AA outputs associated with barley samples for growing-finishing pigs using the regression analysis technique with dual digestibility markers. Six barrows, with 30.5 and 58.6 kg average initial and final BW, were fitted with a simple T-cannula at the distal ileum and fed six barley-based diets at close to ad libitum feed intake according to a 6 x 6 Latin square design. The six diets contained 97% of six barley samples varying from low to high in CP and AA contents (8.5, 9.2, 9.8, 11.5, 12.6, and 15.6% CP, respectively, on DM basis). The dietary NDF content ranged from 16.8 to 23.8% on DM basis. Chromic oxide (Cr2O3) and acid-insoluble ash (AIA) were used as digestibility markers. Each experimental period lasted 7 d. Ileal digesta were collected, at 2-h intervals, for a total of 24 h during d 6 and 7. There were linear relationships (P < 0.01) between dietary contents of apparent ileally digestible and total CP and AA as determined by using either Cr2O3 or AIA as a digestibility marker. The use of Cr2O3 vs AIA affected (P < 0.01) the determination of true ileal AA digestibility coefficients and the endogenous CP and AA outputs. However, there were no differences (P > 0.01) in the true ileal AA digestibility coefficients in barley samples between this study and the average values reported in the literature. The endogenous CP and AA outputs determined in this study were higher (P < 0.01) than reported values (35.1+/-3.0 vs 14.7+/-1.1 g CP/kg DMI). It is concluded that dual digestibility markers should be used to measure true ileal AA digestibility coefficients and endogenous AA outputs when dietary fiber content is high and the ileal digesta is collected through a simple T-cannula in the pig. True rather than apparent ileal AA digestibility coefficients determined in barley samples should be used in diet formulation for swine. The gastrointestinal endogenous AA secretion, recycling, and output losses are important in whole-body AA utilization and homeostasis, especially when fiber-enriched diets are fed to growing-finishing pigs.     

低磷日粮对生长猪生产性能、养分消化率和经济效益的影响

选用288头体重26kg左右、体质健康的杜×长×大三元杂交生长猪,随机分为两组,每组三个重复,以玉米-豆粕-小麦型为基础日粮,对照组日粮参照NRC(1998)标准设计,试验组日粮添加0.33%的磷酸氢钙,且日粮的有效磷(AP)水平为0.205%。试验期30d。研究了低磷日粮对生长猪的生长性能、养分利用及其对环境的影响。结果表明:在不影响猪磷营养需要的条件下,能有效的改善猪排泄物中磷对环境的污染,具有极大的经济和生态效益。     

鸡盲肠对饲料磷的消化作用

本文采用去盲肠和有盲肠公鸡的对比试验方法研究了盲肠对饲料磷的消化作用。结果表明：（１）去盲肠鸡内源磷排泄量为４９ｍｇ／日．只,有盲肠鸡的内源磷排泄量为４２ｍｇ／日．只,两者差异极显著（Ｐ〈０．０１）,可见,盲肠能够消化吸收内源磷;（２）当公鸡采食含豆粕、棉仁粕、菜籽粕、花生粕或胡麻粕的半纯合日粮时,植酸磷采食量较高,有盲肠鸡磷的排泄量显著低于去盲肠鸡,真消化率显著高于去盲肠鸡（Ｐ〈０．０５）,表明     

Effects of level of supplemental phytase on ileal digestibility of amino acids, calcium, and phosphorus in dehulled soybean meal for growing pigs.

Ileally cannulated pigs were used to assess the effects of four dietary levels of microbial phytase (Natuphos) on the apparent and true digestibility of Ca, P, CP, and AA in dehulled soybean meal. Fourteen pigs (25 kg initial BW) were surgically fitted with T-cannulas at the terminal ileum and assigned to diets in a replicated 7 x 7 Latin square design. Following a 14-d recovery, four diets consisting of 30.5% soybean meal with 0, 500, 1,000, or 1,500 units of phytase/kg of diet were fed. Diets 5 (1.05% lysine, 0.90% Ca, and 0.75% P) and 6 (1.05% lysine, 0.90% Ca, and 0.75% P) contained 35.25% soybean meal and 27.0% soy protein concentrate, respectively. Diet 7 (0.37% lysine, 0.03% Ca, and 0.05% P) was a low-CP, casein-based diet used to estimate the nonspecific endogenous losses of Ca, P, CP, and AA in order to estimate the true digestibility of these nutrients. All diets contained cornstarch and dextrose and were fortified with vitamins and minerals. Chromic oxide was used as an indigestible indicator. The diets were fed daily at 9% of metabolic BW (BW0.75). Apparent and true ileal digestibility of P increased quadratically (P < 0.01) and true digestibility of Ca increased linearly (P < 0.07) with increasing levels of phytase. Apparent digestibility of Ca was unaffected (P = 0.15) by phytase level. Apparent and true ileal digestibility of CP and most AA increased slightly with the addition of 500 units of phytase/kg of diet, but not at higher levels of phytase supplementation (in most cases, cubic effect, P < 0.05). Apparent and true ileal nutrient digestibility coefficients were unaffected by soybean meal source (Diet 1 vs Diet 5), except for arginine and Ca. The apparent and true digestibility coefficients for most of the AA tended (P < 0.10) to be lower in diets containing soy protein concentrate vs the common source of soybean meal used in Diet 5, but ileal digestibilities of Ca and P were unaffected (P = 0.15). In this study, supplemental microbial phytase did not improve the utilization of AA provided by soybean meal but was an effective means of improving Ca and P utilization by growing swine fed soybean meal-based diets.