Department of Animal Science, Morrison Hall, Cornell University, Ithaca, NY14853, USA.
United States Department of Agriculture - Agricultural Research Service, U.S. Dairy Forage Research Center, Madison, WI53706, USA.
Br J Nutr. 2020 Oct 14;124(7):693-700. doi: 10.1017/S0007114520001713. Epub 2020 May 14.
Although lignin has been negatively correlated with neutral-detergent fibre (NDF) digestibility (NDFD) in ruminants and used to predict potential extent of NDF digestion of forages, selection of an analysis, Klason lignin (KL) or acid-detergent lignin (ADL), to describe that the nutritionally relevant lignin has not been resolved. Dismissed as an artifact is the difference between KL and ADL (ΔL). A question is whether ΔL influences NDFD. We evaluated the relationships of ΔL, KL and ADL with NDFD in order to determine the nutritionally homogeneous or heterogeneous nature of KL. Data sets from two laboratories (DS1 and DS2) were used that included ADL, KL and in vitro NDFD at 48 h (NDFD48). DS1 contained seven C3 grasses, seventeen C4 maize forages and nineteen alfalfas, and DS2 had fifteen C3 grasses, eight C4 forages and six alfalfas. Mean ΔL was greater than ADL in C3 and C4 samples and less in alfalfas. Within forage type and laboratory, ΔL was not correlated with NDFD48 (r -0·34-0·49; all P > 0·17). ADL was more consistently correlated with NDFD48 (r -0·47--0·95; P < 0·01-0·21) than with KL (r 0·03--0·91; P < 0·01-0·94). ΔL as a proportion of KL was correlated with NDFD48 in C3 and C4 samples (r 0·44-0·76; P < 0·01-0·08). The differing behaviours of ΔL and ADL relative to NDFD48 indicate that KL is a nutritionally heterogeneous fraction, the behaviour of which may vary by forage type and ratios of ADL and ΔL present.
虽然木质素与反刍动物中性洗涤纤维（NDF）消化率（NDFD）呈负相关，并被用于预测饲料中 NDF 消化的潜在程度，但在描述具有营养相关性的木质素时，选择分析方法，如 Klason 木质素（KL）或酸性洗涤木质素（ADL），仍未得到解决。KL 与 ADL 之间的差异（ΔL）被认为是一种假象。问题是ΔL 是否会影响 NDFD。我们评估了 ΔL、KL 和 ADL 与 NDFD 的关系，以确定 KL 的营养均匀性或异质性。使用了来自两个实验室（DS1 和 DS2）的数据，包括 ADL、KL 和 48 小时体外 NDFD（NDFD48）。DS1 包含七种 C3 草、十七种 C4 玉米饲料和十九种紫花苜蓿，DS2 则包含十五种 C3 草、八种 C4 饲料和六种紫花苜蓿。C3 和 C4 样本中的平均 ΔL 大于 ADL，而在紫花苜蓿中则较小。在饲草类型和实验室中，ΔL 与 NDFD48 不相关（r -0·34-0·49；均 P > 0·17）。ADL 与 NDFD48 的相关性更一致（r -0·47--0·95；P < 0·01-0·21），而 KL 的相关性则更不一致（r 0·03--0·91；P < 0·01-0·94）。在 C3 和 C4 样本中，KL 中 ΔL 的比例与 NDFD48 相关（r 0·44-0·76；P < 0·01-0·08）。ΔL 和 ADL 相对于 NDFD48 的不同行为表明，KL 是一种具有营养异质性的成分，其行为可能因饲草类型和 ADL 与 ΔL 的比值而异。
