Abstract

Indigestible components, including indigestible dry matter (iDM) and indigestible neutral detergent fiber (iNDF), play an integral role as internal markers for determining ruminal kinetics and digestibility estimations. However, the accuracy of internal markers is dependent upon the incubation technique utilized as bag type (BT) and incubation length (IL) can be significant sources of error. Previous studies have primarily focused on iDM and iNDF as digestibility markers, but few studies have compared digestibility estimates to those of acid detergent insoluble ash (ADIA). Therefore, our objective was to investigate the effect of BT (F57, F58, and Dacron) and IL (288 and 576 h) on iDM and iNDF residues, DM and NDF digestibilities, and fecal recoveries when using in situ incubations. Additionally, we evaluated the accuracy of digestibility estimates when using iDM, iNDF, and ADIA. For iDM and iNDF, feed residues demonstrated a BT × IL interaction (P < 0.01). However, fecal residues were only influenced by the main effects of BT and IL (P < 0.01), with the F58 BT and 288-h IL having the greatest residues for both iDM and iNDF. The variation in residues was greatly reduced when using iNDF compared with iDM. Fecal recovery estimates most closely approximated 100% recovery when utilizing ADIA and iDM using the F57 × 576 h incubation method (P < 0.01), although recovery was overestimated for all incubation combinations. Fecal NDF recovery estimates better represented the excretion profiles when the F57 × 576 h combination was used with iDM as the internal marker (P < 0.01). Estimates of DM and NDF digestibility were the most accurate when utilizing ADIA (P < 0.01) relative to all other treatments. Our results indicate that the proper methodological application is specific to the purpose of the inferences. When evaluating fecal recoveries and digestibility, ADIA or iDM with F57 at 576-h in situ incubation provides the greatest accuracy.

中文翻译：

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比较原位技术来评估难消化成分的回收率和消化率估计的准确性

摘要

难消化的成分，包括难消化的干物质 ( iDM ) 和难消化的中性洗涤纤维 ( iNDF )，作为确定瘤胃动力学和消化率估计的内部标记起着不可或缺的作用。然而，内部标记的准确性取决于使用的孵化技术，因为袋型 ( BT ) 和孵化长度 ( IL ) 可能是重要的误差来源。以前的研究主要集中在 iDM 和 iNDF 作为消化率标志物，但很少有研究将消化率估计值与酸性洗涤剂不溶性灰分 ( ADIA）。因此，我们的目标是研究 BT（F57、F58 和 Dacron）和 IL（288 和 576 小时）对 iDM 和 iNDF 残留、DM 和 NDF 消化率以及使用原位孵育时粪便回收率的影响。此外，我们评估了使用 iDM、iNDF 和 ADIA 时消化率估计的准确性。对于 iDM 和 iNDF，饲料残留物表现出 BT × IL 相互作用（P < 0.01）。然而，粪便残留仅受 BT 和 IL 的主要影响（P < 0.01），其中 F58 BT 和 288-h IL 对 iDM 和 iNDF 的残留量最大。与 iDM 相比，使用 iNDF 时残基的变化大大减少。当使用 F57 × 576 h 培养方法使用 ADIA 和 iDM 时，粪便回收率估计最接近 100% 回收率（P< 0.01)，尽管所有孵育组合的回收率都被高估了。当 F57 × 576 h 组合与 iDM 作为内部标记一起使用时，粪便 NDF 回收率估计值更好地代表了排泄曲线（P < 0.01）。相对于所有其他处理，使用 ADIA 时对 DM 和 NDF 消化率的估计最准确（P < 0.01）。我们的结果表明，适当的方法学应用特定于推论的目的。在评估粪便回收率和消化率时，ADIA 或 iDM 与 F57 在 576 小时的原位孵育可提供最大的准确性。