Characterization of the nutritive value of perennial ryegrass (Lolium perenne L.) dominated pastures using updated chemical methods with application for the Cornell Net Carbohydrate and Protein System
Characterization of the nutritive value of perennial ryegrass (Lolium perenne L.) dominated pastures using updated chemical methods with application for the Cornell Net Carbohydrate and Protein System
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DOI：
10.1016/j.anifeedsci.2020.114752
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发表时间：
2021-01-30
影响因子：
3.2
通讯作者：
Amburgh, M. E. Van
中科院分区：
文献类型：
--
作者：
Dineen, M.;McCarthy, B.;Amburgh, M. E. Van
反刍动物营养模型，如康奈尔净碳水化合物和蛋白质系统（CNCPS），随着时间的推移而不断发展，从而提高了预测动物生产性能的精度和准确性。随着这种演变，已经开发出更精确和准确的方法来描述进行模型模拟所需的饲料化学输入。然而，这些更新的方法尚未应用于基于牧场的系统。采用综合饲料化学方法，研究了多年生黑麦草（Lolium perenne L.； PRG）优势牧草的营养价值。本研究使用了来自三个独立实验的55个样本。生成的数据表明，淀粉酶和亚硫酸钠处理的NDF对灰渣的校正（aNDFom）方法显著低于淀粉酶和亚硫酸钠处理的NDF （aNDF）方法；因此，由于灰污染，aNDF一直高估了PRG中细胞壁含量的真实测量值。多个时间点体外和form消化率分析的结果表明，未成熟的PRG由一个大的潜在可消化池组成，降解速度很快。30h、120h、240h的时间点能更好地描述PRG的andform降解曲线。另外，发酵240 h时未消化的andform受PRG类别的影响；其中，春季和夏季最低（分别为98和111 g/kg），秋季居中（155 g/kg），干旱胁迫牧场最高（200 g/kg）。240 h前未达到体外andform消化的程度；然而，120-h和240-h时间点之间的强Pearson相关系数（0.98）表明从120-h时间点预测未消化andform的潜力。根据CNCPS采用的N分选方案，大部分PRG N是可溶的，并且可能在瘤胃中高度降解。需要一种能够定量描述PRG N瘤胃降解的测定方法。使用单一的21小时HC1水解来确定氨基酸浓度，低估了Ile和Val的浓度，这表明需要多次水解时间程序来预测PRG的真实氨基酸浓度。总之，本研究中更新的饲料化学程序可以更准确地表征PRG的营养价值。与CNCPS等配方模型相结合，这种加深的理解可以提供关于PRG如何与反刍动物相互作用的更可靠信息，从而提高基于牧场的系统的效率和生产力。
Ruminant nutrition models, such as the Cornell Net Carbohydrate and Protein System (CNCPS), have evolved over time resulting in increased precision and accuracy with which they can predict animal performance. In tandem with this evolution, more precise and accurate methodologies have been developed to describe the feed chemistry inputs required to conduct model simulations. However, these updated methods have not been applied to pasture-based systems. The objective of this study was to characterize the nutritive value of perennial ryegrass (Lolium perenne L.; PRG) dominated pastures using comprehensive feed chemistry methods. Fifty-five samples from three independent experiments were used in this study. The data generated demonstrated that the amylase- and sodium sulphite-treated NDF corrected for ash residue (aNDFom) method was significantly lower than the amylase- and sodium sulphite-treated NDF (aNDF) method; hence, due to ash contamination, aNDF consistently overestimated the true measure of cell wall content in PRG. Results from multiple time point in vitro aNDFom digestibility analysis indicated that immature PRG comprises of a large potentially digestible pool that degrades at a rapid rate. A 12-h time point combined with 30, 120, and 240 h better describes the aNDFom degradation curve of PRG. In addition, undigested aNDFom at 240 h of fermentation was affected by PRG category; whereby, spring and summer were lowest (98 and 111 g/kg of aNDFom, respectively), autumn intermediate (155 g/kg of aNDFom), and drought stressed pastures the highest (200 g/kg of aNDFom). The extent of in vitro aNDFom digestion was not reached prior to 240 h; however, a strong Pearson correlation coefficient between 120-h and 240-h time points (0.98) indicated the potential to predict undigested aNDFom from the 120-h time point. Based on the N fractionation scheme employed by the CNCPS, a large proportion of PRG N is soluble and likely highly degradable in the rumen. An assay capable of quantitatively describing the rumen degradation of PRG N is required. Using a single 21-h HC1 hydrolysis, to determine amino acid concentration, underestimated the concentration of Ile and Val indicating that multiple-hydrolysis time procedures are required to predict the true amino acid concentration of PRG. In conclusion, the updated feed chemistry procedures conducted in this study, allowed a more accurate characterization of the nutritive value of PRG. This increased understanding in combination with formulation models, such as the CNCPS, can provide more robust information on how PRG interacts with the ruminant animal, in order to increase the efficiency and productivity of pasture-based systems.