导读

黑麦草（Lolium perenne L.）是一种多年生的优质牧草，长期以来，爱尔兰奶农在牧场广泛种植黑麦草。近年来，人们对在奶牛放牧系统中进行多种牧草混播的兴趣越来越高，诸如车前草和菊苣等草种与黑麦草、白三叶、红三叶一起进行混播种植。这种混播种植方式是由提高用于动物生产的牧场质量和减少牧草季节性供应驱动的。白三叶可以改善牧草品质，并增加产奶量，同时在减少氮肥施用量的情况下保持较高的干物质量。农户开始有兴趣将红三叶草与黑麦草进行混播，以提高青贮质量并降低氮肥成本。

爱尔兰农业与食品发展部、都柏林大学的Ciarán Hearn等学者于2021年在放牧季节采用样地放牧研究方法，探讨了不同草种（多年生黑麦草、豆科和禾本科植物）在放牧草地上的潜在贡献。设置了10种牧草混播类型，每种草地类型分别施氮0、100、150和200 kg hm−2。除多年生黑麦草外，取样时间和混播对其他牧草的物种丰度有显著的交互作用，施氮量和混播对多年生黑麦草有显著交互作用。此外，除牧草的消化率外，取样时间与混播之间以及取样时间与施氮之间的相互作用与牧草营养成分有关。氮素添加影响了混播草地中白三叶的生长，高施氮量使白三叶的生长水平下降。混播草地牧草粗蛋白含量的增加与添加白三叶有关，而由于加入了车前草，其营养价值存在明显的季节性变化。中性洗涤纤维和粗蛋白含量直接影响混合饲料的整体品质，白三叶在混合饲草中的比例对中性洗涤纤维和粗蛋白含量影响较大。车前草的加入对混播草地的牧草季节性供应和动物干物质摄入量有较高贡献，但在某些季节观察到牧草的消化率下降。

作者认为，在集约放牧条件下，多年生黑麦草、白三叶和车前的混播草地可以生产出稳定且营养均衡的饲草料。总的来说，该研究为农民和反刍动物营养学家提供了温带放牧系统中使用多种牧草饲养奶牛的理论依据。

原文图表

FIGURE There was an effect of sward species mixture on sward crude protein (g kg−1 DM) across all nitrogen application rates. Results indicate that white clover has a significant influence on sward protein content; this is further influenced by the growth habit of white clover over the course of a growing season.

TABLE 1 Monthly and annual nitrogen (N) fertiliser applications (kg N ha−1) for each N application treatment.

TABLE 2 Significance (p) values offixed effects on model dependent variable.

Abbreviations: ADF, acid detergent fibre; CP, crude protein; N, nitrogen; NDF, neutral detergent fibre; NS, not significant; OMD, organic matter digestibility.

TABLE 3 Seasonal sward chemical composition (g kg−1DM), LS‐means presented with the standard error of seasonal mean.

Note:T1, T2, T3 and T4 refer to spring (March 5), early summer (May 13), late summer (July 7) and autumn (August 27), respectively. Within rows, swards with differing superscript letters (abcdef) differ significantly (p< 0.05); within columns, time points with differing superscript symbols (*^!~) differ significantly (p< 0.05) within the chemical fraction.
Abbreviations: ADF, acid detergent fibre; CH, chicory; CP, crude protein; NDF, neutral detergent fibre; OMD, organic matter digestibility; PRG, perennial ryegrass; PL, ribwort plantain; RC, red clover; SEM, standard error of means; WC, white clover.

TABLE 4 Annual sward botanical and chemical composition; data presented are LS‐means ± standard error.

Note: Within rows, swards with differing superscript letters (abcdef) differ significantly (p< 0.05).
Abbreviations: ADF, acid detergent fibre; CH, chicory; CP, crude protein; NDF, neutral detergent fibre; OMD, organic matter digestibility; PRG, perennial ryegrass; PL, ribwort plantain; RC, red clover; WC, white clover.

TABLE 5 Seasonal chemical composition (g kg−1DM) as affected by N application; data presented are LS‐means ± standard error.

Note: T1, T2, T3 and T4 refer to spring (March 5), early summer (May 13), late summer (July 7) and autumn (August 27), respectively. Within rows, nitrogen application rates with differing superscript letters (abc) differ significantly (p< 0.05); within columns, time points with differing superscript symbols (*^!~) differ significantly (p< 0.05)within chemical fraction.
Abbreviations: ADF, acid detergent fibre; CP, crude protein; NDF, neutral detergent fibre; OMD, organic matter digestibility.

TABLE 6 Seasonal sward botanical composition (% DM), LSmeans presented with the standard error of seasonal means.

Note: T1, T2, T3 and T4 refer to spring (March 5), early summer (May 13), late summer (July 7) and autumn (August 27), respectively. Within rows, swards with differing superscript letters (abcde) differ significantly (p< 0.05); within columns, time points with differing superscript symbols (*^!~) differ significantly (p< 0.05) within species category.
Abbreviations: CH, Chicory; PRG, perennial ryegrass; PL, ribwort plantain; RC, red clover; SEM, standard error of means; WC, white clover.

TABLE 7 Sward botanical composition (% DM) as affected by nitrogen application, LS‐means presented with the standard error of nitrogen application means.

Note: Within rows, swards with differing superscript letters (abcdef) differ significantly (p< 0.05); within columns, nitrogen application rates with differing superscript symbols (*^!~)differ significantly (p< 0.05) within species category.
Abbreviations: CH, Chicory; PRG, perennial ryegrass; PL, ribwort plantain; RC, red clover; SEM, standard error of means; WC, white clover.

扫码查看原文

原文链接：https://onlinelibrary.wiley.com/doi/epdf/10.1002/glr2.12037

内容来源：Grassland Research（草地研究）第1卷第4期（投稿：2022-12-05；接收：2022-12-14；刊发：2023-01-20）

DOI：https://doi.org/10.1002/glr2.12037

引用格式：Hearn, C., Egan, M., Lynch, M. B., Fleming, C., & O'Donovan, M. (2022). Seasonal variations in nutritive and botanical composition properties of multispecies grazing swards over an entire dairy grazing season. Grassland Research, 1(4), 221–233.

文章信息编译者：贾倩民 兰州大学草地农业科技学院 青年研究员

说明：该文仅代表编译者对论文的理解，如需参考和引用相关内容，请查阅原文。

期刊介绍

Grassland Research是我国草业科学领域第一本国际学术期刊，季刊，由中国草学会和兰州大学共同主办。该刊受中国科技期刊卓越计划高起点新刊项目支持，由国际出版集团John Wiley & Sons Australia, Ltd.提供出版及宣传服务，于2022年正式出版。

Grassland Research论文刊发范围广，综合性强。从分子到全球变化层面，全维度聚焦草业科学及其在人类可持续发展中的作用。期刊将刊登天然草原，栽培草地、草坪和生物能源作物，以及草地生态系统三大板块的基础性和应用性研究成果、综述、论点等类型的文章。优先考虑发表青年学者优秀研究成果，期待成为青年科学家喜爱的国际学术交流主阵地。

在创刊前三年，Grassland Research将免收版面费，以OA形式通过全球化出版平台Wiley Online Library出版

排版 | 陈媛

执行编辑 | 范思佳

审核 | 彭京伦 武艳培 王新宇