Favero A, Ragland D, Vieira S L, Owusu-Asiedu A, Adeola O
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907-2054 Departamento de Zootecnia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907.
J Anim Sci. 2014 Dec;92(12):5583-92. doi: 10.2527/jas.2014-7919. Epub 2014 Nov 17.
Two experiments using soybean meal (SBM) or canola meal (CM) were conducted to investigate whether the choice of digestibility marker influenced the apparent ileal digestibility (AID) or standardized ileal digestibility (SID) of N and AA in diets supplemented with phytase. In each experiment, 18 barrows fitted with T-cannulas at the ileocecal junction were assigned to 3 diets consisting of a N-free diet to determine endogenous losses of N and AA, a semipurified diet (SBM in Exp. 1 or CM in Exp. 2), and the semipurified diet supplemented with phytase at 1,000 phytase units/kg. Three digestibility markers including acid-insoluble ash (AIA), chromic oxide (Cr2O3), and titanium dioxide (TiO2) were added to each diet at 3 g/kg. Each diet was fed for 7 d, consisting of a 5-d adjustment and a 2-d collection of ileal digesta. In both studies, basal ileal endogenous losses determined with Cr2O3 as a digestibility marker were lower (P<0.01) than with those determined with AIA or TiO2 digestibility markers. Using SBM as the protein source in Exp. 1, there was no interaction between phytase and digestibility marker on AID or SID of AA. The AID of N and AA in SBM using AIA as a digestibility marker tended to be lower (P<0.1) compared with Cr2O3 or TiO2 digestibility markers. Phytase supplementation increased (P<0.001) the AID of Ca and P. The use of AIA or Cr2O3 digestibility marker tended to be associated with lower (P<0.1) SID values compared with TiO2. Phytase did not affect the SID of N or any AA in SBM except for Met, for which there was an increase (P<0.05) with phytase supplementation. Using CM as the protein source in Exp. 2, there were significant interactions between digestibility marker and phytase. Phytase supplementation had effects (P<0.01) on AID or SID when Cr2O3 or TiO2 was used as the digestibility marker. With Cr2O3 or TiO2 as the digestibility marker in the CM diets, phytase supplementation increased (P<0.05) the SID of N and all AA (except Trp). There was no SID of N or AA response to phytase supplementation of CM when AIA was used as a digestibility marker. In contrast, there were no clear improvements in AA digestibility from phytase supplementation for SBM. Phytase effects on AID or SID of AA were dependent on the digestibility marker used in diets when CM was used as the protein source but not when SBM was used as the protein source. Therefore, AA digestibility response to phytase supplementation may depend on the protein being evaluated as well as the choice of digestibility marker.
进行了两项分别使用豆粕（SBM）或油菜籽粕（CM）的试验，以研究消化率标记物的选择是否会影响添加植酸酶日粮中氮和氨基酸的表观回肠消化率（AID）或标准回肠消化率（SID）。在每项试验中，18头在回盲交界处安装了T型套管的公猪被分配到3种日粮组，分别为用于测定氮和氨基酸内源损失的无氮日粮、半纯化日粮（试验1中的SBM或试验2中的CM）以及添加了1000植酸酶单位/千克植酸酶的半纯化日粮。在每种日粮中添加3种消化率标记物，包括酸不溶性灰分（AIA）、三氧化二铬（Cr2O3）和二氧化钛（TiO2），添加量为3克/千克。每种日粮饲喂7天，包括5天的适应期和2天的回肠食糜收集期。在两项研究中，以Cr2O3作为消化率标记物测定的基础回肠内源损失均低于（P<0.01）以AIA或TiO2作为消化率标记物测定的结果。在试验1中使用SBM作为蛋白质来源时，植酸酶和消化率标记物对氨基酸的AID或SID没有交互作用。与Cr2O3或TiO2消化率标记物相比，以AIA作为消化率标记物时，SBM中氮和氨基酸的AID往往较低（P<0.1）。添加植酸酶提高了（P<0.001）钙和磷的AID。与TiO2相比，使用AIA或Cr2O3消化率标记物时，SID值往往较低（P<0.1）。除蛋氨酸外，植酸酶对SBM中氮或任何氨基酸的SID没有影响，添加植酸酶后蛋氨酸的SID有所增加（P<0.05）。在试验2中使用CM作为蛋白质来源时，消化率标记物和植酸酶之间存在显著交互作用。当使用Cr2O3或TiO2作为消化率标记物时，添加植酸酶对AID或SID有影响（P<0.01）。在CM日粮中以Cr2O3或TiO2作为消化率标记物时，添加植酸酶提高了（P<0.05）氮和所有氨基酸（色氨酸除外）的SID。当使用AIA作为消化率标记物时，CM添加植酸酶后氮或氨基酸的SID没有变化。相比之下，添加植酸酶对SBM的氨基酸消化率没有明显改善。当以CM作为蛋白质来源时，植酸酶对氨基酸AID或SID的影响取决于日粮中使用的消化率标记物，而以SBM作为蛋白质来源时则不然。因此，氨基酸消化率对添加植酸酶的反应可能取决于所评估的蛋白质以及消化率标记物的选择。
