Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
J Anim Sci. 2022 Jun 1;100(6). doi: 10.1093/jas/skac181.
Increased fermentable carbohydrates (e.g., β-glucan, amylose) may increase endogenous losses including for P, and thereby reduce apparent total tract digestibility (ATTD) of P. The present study assessed effects of barley cultivars varying in fermentable starch and fiber on apparent ileal digestibility (AID) and ATTD of P, myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate; InsP6) and Ca, and standardized total tract digestibility (STTD) of P and the presence of lower inositol phosphates (InsP) compared to wheat. In a 6 (period) × 5 (diet) Youden square, seven ileal-cannulated barrows (initial BW, 27.7 kg) were fed diets containing 80% of one of five cereal grains differing in amylose, β-glucan, and fiber content: 1) high-fermentable, high-β-glucan, hull-less barley (HFB); 2) high-fermentable, high-amylose, hull-less barley (HFA); 3) moderate-fermentable, hull-less barley (MFB); 4) low-fermentable, hulled barley (LFB); and 5) low-fermentable, Canadian Western Red Spring wheat (LFW). On dry matter (DM) basis, cereal grains contained between 0.32% to 0.53% total P and 0.24% to 0.50% InsP6-P. The InsP6-2-P was calculated as the sum of all detected InsP-P (InsP6-P to InsP2-P) in the sample. The P release of degraded InsP-P was calculated by using the following equation: sum InsP6-2-Pdiet (g/kg DM) × (AID or ATTD sum InsP6-2-P (%)/ 100). Data were analyzed using a mixed model with diet as fixed effect, and pig and period as random effects. On DM basis, diets contained 41.4% to 50.6% starch, 0.88% to 8.54% β-glucan, 0.81% to 0.89% total P, and 0.19% to 0.35% InsP6-P. The MFB, LFB, and LFW had greater (P < 0.05) diet AID of P than HFB and HFA, and MFB had greater (P < 0.05) diet ATTD and STTD of P than HFB. The ATTD of InsP6-P was greater (P < 0.05) for HFB than LFB and the ATTD of the sum InsP6-2-P was greater (P < 0.05) for HFB and HFA than LFB. Total tract P release was greater (P < 0.001) for HFB, HFA, and LFW than MFB and LFB. The LFW had greater (P < 0.05) ATTD of Ca than LFB. Diet β-glucan content was not correlated with STTD of P (R2 = 0.03) or ATTD of InsP6 (R2 = 0.05). In conclusion, cereal grains high in fermentable fiber, e.g., amylose and β-glucans included in specific hull-less barley cultivars, had lower diet AID, ATTD, and STTD of P, but greater ATTD of InsP6-P and sum InsP6-2-P. Carbohydrate fermentation, thus, results in greater total tract P release from InsP-P hydrolysis.
增加可发酵碳水化合物（例如β-葡聚糖、直链淀粉）可能会增加内源损失，包括磷，从而降低磷的表观全肠道消化率（ATTD）。本研究评估了不同可发酵淀粉和纤维含量的大麦品种对磷的表观回肠消化率（AID）和 ATTD、肌醇 1,2,3,4,5,6-六磷酸（二氢磷酸盐；InsP6）和钙以及磷和更低的肌醇磷酸（InsP）的标准化全肠道消化率（STTD）的影响与小麦相比。在 6（期）×5（日粮）的约登正方形中，7 头回肠插管的阉公猪（初始 BW，27.7 kg）饲喂含有 5 种谷物中的 1 种的 80%的日粮，这些谷物在直链淀粉、β-葡聚糖和纤维含量上有所不同：1）高发酵、高β-葡聚糖、无壳大麦（HFB）；2）高发酵、高直链淀粉、无壳大麦（HFA）；3）中发酵、无壳大麦（MFB）；4）低发酵、带壳大麦（LFB）；和 5）低发酵、加拿大西部红春小麦（LFW）。基于干物质（DM），谷物中含有 0.32%至 0.53%的总磷和 0.24%至 0.50%的 InsP6-P。InsP6-2-P 被计算为样品中所有检测到的 InsP-P（InsP6-P 至 InsP2-P）的总和。通过使用以下公式计算降解 InsP-P 的磷释放量：饲料中总 InsP6-2-P 量（g/kg DM）×（AID 或 ATTD 总 InsP6-2-P%/100）。数据使用混合模型进行分析，日粮为固定效应，猪和时期为随机效应。基于 DM，日粮含有 41.4%至 50.6%的淀粉、0.88%至 8.54%的β-葡聚糖、0.81%至 0.89%的总磷和 0.19%至 0.35%的 InsP6-P。MFB、LFB 和 LFW 的日粮磷 AID 高于 HFB 和 HFA（P<0.05），MFB 的日粮磷 ATTD 和 STTD 高于 HFB（P<0.05）。HFB 的 InsP6-P ATTD 高于 LFB（P<0.05），HFB 和 HFA 的 InsP6-2-P 总和 ATTD 高于 LFB（P<0.05）。HFB、HFA 和 LFW 的全肠道磷释放量高于 MFB 和 LFB（P<0.001）。LFW 的日粮钙 ATTD 高于 LFB（P<0.05）。日粮 β-葡聚糖含量与磷的 STTD（R2=0.03）或 InsP6 的 ATTD（R2=0.05）不相关。总之，富含可发酵纤维的谷物，例如特定无壳大麦品种中的直链淀粉和β-葡聚糖，其日粮磷的 AID、ATTD 和 STTD 较低，但 InsP6-P 和 InsP6-2-P 的总和 ATTD 较高。碳水化合物发酵导致来自 InsP-P 水解的总肠道磷释放增加。
