U.S. Department of Agriculture-Agriculture Research Service, Ames, IA.
Oak Ridge Institute for Science and Education, Oak Ridge, TN.
J Anim Sci. 2020 Feb 1;98(2). doi: 10.1093/jas/skaa026.
Two experiments were conducted to determine the effect of oven drying (OD) or freeze drying (FD) on apparent ileal digestibility (AID) of AA in diets fed to pigs. In experiment 1, 15 barrows (88.4 ± 6.4 kg) were allotted to either a corn starch-soybean meal (CST), potato starch-soybean meal (PST), or corn-soybean meal (CSBM) diet, over 2 collection periods. Following collection, samples were pooled within pig and subdivided into either OD or FD, resulting in 10 observations per diet by drying-method combination. In experiment 2, 11 barrows (63.3 ± 3.8 kg) were fed a CST diet, and, following collection, samples were pooled within pig and subdivided and either adjusted to pH 4 or remain unadjusted. Subsets of these samples were then subdivided to be either FD or OD, resulting in 11 observations per pH level by drying-method combination. OD was accomplished by drying samples in a forced air oven at either 100 °C (experiment 1) or 75 °C (experiment 2). In experiment 1, there was no diet type by drying-method interactions noted for any of the AA (P > 0.10).OD resulted in a higher AID of AA compared with samples which were FD (P ≤ 0.10), for all AA except for Gly and Tyr. Averaged across all AA, AID of AA was 3.3% greater if the sample was OD compared with FD. Differences in AID of AA among the 3 diets were noted for all AA (P ≤ 0.07), except for Cys (P = 0.33), due to the fact that CST and PST diets only contained soybean meal (SBM) as an AA-providing ingredient while the CSBM diet contained both corn and SBM. Pigs fed the PST diet had greater SID for all AA compared with pigs fed the CST diet (P ≤ 0.05), except for His, Lys, Cys, and Glu. In experiment 2, there were no pH-adjustment by drying-method interactions noted on AID for any of the AA (P > 0.10). Adjusting ileal digesta to a pH of 4.0 had little effect on AID for most of the AA, except for a lowered AID of Arg, His, Lys, Trp, and Ser (P ≤ 0.10). OD resulted in a higher AID for all AA (P ≤ 0.09) except for Ile, Thr, Val, Ala, Asp, Glu, and Gly. Averaged across all AA, the increase in AID of AA was 1.7% greater if the sample was OD compared with FD. On average, OD of ileal digesta resulted in a 2.5% greater estimate of AID of AA compared with samples that were FD, and was not diet-, pH-, or AA-dependent. Because the majority of the data on AA digestibility are based on FD, a bias factor may be necessary to adjust AA digestibility data obtained on an OD-basis relative to an FD-basis for use in feed formulation.
进行了两项实验来确定在猪饲料中使用烤箱干燥（OD）或冷冻干燥（FD）对 AA 的表观回肠消化率（AID）的影响。在实验 1 中，15 头阉公猪（88.4 ± 6.4kg）被分配到玉米淀粉-豆粕（CST）、马铃薯淀粉-豆粕（PST）或玉米-豆粕（CSBM）日粮中，进行 2 个采集期。采集后，将样品在猪内混合并分为 OD 或 FD，每个日粮-干燥方法组合有 10 个观察值。在实验 2 中，11 头阉公猪（63.3 ± 3.8kg）喂食 CST 日粮，采集后，将样品在猪内混合并分为 pH 值 4 或不调整，然后将这些样品的子集分为 FD 或 OD，每个 pH 水平的干燥方法组合有 11 个观察值。OD 通过在 100°C（实验 1）或 75°C（实验 2）的强制空气烘箱中干燥样品来完成。在实验 1 中，对于所有 AA（P＞0.10），没有发现日粮类型与干燥方法之间的相互作用。与 FD 相比，OD 导致 AA 的 AID 更高（P≤0.10），除了 Gly 和 Tyr 以外的所有 AA。与 FD 相比，所有 AA 的 AID 平均增加了 3.3%。在所有 3 种日粮中，所有 AA 的 AA AID 差异均有统计学意义（P≤0.07），除了 Cys（P=0.33），这是因为 CST 和 PST 日粮仅含有豆粕（SBM）作为 AA 提供成分，而 CSBM 日粮则含有玉米和 SBM。与 CST 日粮相比，喂食 PST 日粮的猪所有 AA 的 SID 更高（P≤0.05），除了 His、Lys、Cys 和 Glu。在实验 2 中，对于所有 AA（P＞0.10），未发现 pH 值调整与 AID 之间存在干燥方法的相互作用。将回肠消化物调整到 pH 值 4.0 对大多数 AA 的 AID 影响不大，除了 Arg、His、Lys、Trp 和 Ser 的 AID 降低（P≤0.10）。OD 导致所有 AA 的 AID 更高（P≤0.09），除了 Ile、Thr、Val、Ala、Asp、Glu 和 Gly。与 FD 相比，所有 AA 的 AID 平均增加了 1.7%。平均而言，与 FD 相比，OD 会使 AA 的 AID 估计值增加 2.5%，并且不受日粮、pH 值或 AA 的影响。由于 AA 消化率的数据主要基于 FD，因此在进行饲料配方时，可能需要使用一个偏倚因子来调整基于 OD 获得的 AA 消化率数据与基于 FD 获得的数据。
