Jezequel A, Delaby L, McKay Z C, Fleming C, Horan B
Animal and Grassland Research and Innovation Centre, Teagasc Moorepark, Fermoy, Co. Cork P61C996, Ireland; School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
INRAE, l'Institut Agro, Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage, F-35590 Saint-Gilles, France.
J Dairy Sci. 2024 Dec;107(12):11104-11116. doi: 10.3168/jds.2024-25177. Epub 2024 Sep 27.
The objective of this study was to evaluate the effect of sward diversification combined with a reduction of chemical nitrogen (N) fertilizer on the performance of spring-calving grazing dairy cows within a farm systems experiment. Three farmlets were created: a monoculture of perennial ryegrass (Lolium perenne L.; PRG) fertilized with 250 kg N/ha (PRG-250N), a PRG-white clover (Trifolium repens L; WC) sward fertilized with 125 kg N/ha (PRGWC-125N), and a multispecies sward (MSS) comprising grasses, legumes, and herbs, also fertilized with 125 kg N/ha (MSS-125N). Each farmlet had its own herd of dairy cows on a total area of 18.7 ha divided into 20 paddocks. Each herd comprised pure Holstein-Friesian (HF) and HF-Jersey crossbred (JFX) animals, and cows were randomly assigned through the 3 treatments. For 3 years (2021 to 2023), the performances of both swards (grass yield, botanical composition, nutritive value) and grazing animals (milk production and composition, BW, and BCS) were recorded. We found no significant differences in pasture production or sward nutritive value between sward systems, and grazing season length was also similar (264 d). On average over the 3 years, PRGWC-125N contained 150 g/kg DM of legumes, and MSS-125N contained 160 g/kg DM legumes, 130 g/kg DM plantain, and 40 g/kg DM chicory. Both individual cow milk and fat plus protein (milk solids) yield were lower for PRG-250N (5,018 and 452 kg, respectively), intermediate for PRGWC-125N (5,139 and 463 kg, respectively), and highest for MSS-125N (5,297 and 476 kg, respectively) whereas milk and milk solids production per hectare from grazing were similar during the study period (11,523 and 1,016 kg/ha, respectively). Breed also had a significant effect, with the JFX having lower milk yield but higher fat and protein concentration compared with HF. This resulted in higher milk solids production per kilogram of BW for the JFX compared with HF (0.96 and 0.87 kg milk solids/kg BW, respectively). The results of this study highlight the possibility for more diverse pastures to reduce chemical N fertilizer input requirements and maintain pasture productivity while increasing animal performance within pasture-based spring-calving systems.
本研究的目的是在一个农场系统试验中，评估草地多样化结合减少化学氮肥施用量对春季产犊放牧奶牛生产性能的影响。创建了三个小区：一个是用250千克氮/公顷施肥的多年生黑麦草（Lolium perenne L.；PRG）单一栽培小区（PRG - 250N），一个是用125千克氮/公顷施肥的PRG - 白三叶（Trifolium repens L.；WC）草地小区（PRGWC - 125N），还有一个是包含禾本科、豆科和草本植物的多物种草地（MSS）小区，同样用125千克氮/公顷施肥（MSS - 125N）。每个小区在总面积为18.7公顷的土地上分为20个围场，各有自己的奶牛群。每个牛群由纯种荷斯坦 - 弗里生（HF）和HF - 泽西杂交（JFX）动物组成，奶牛被随机分配到这三种处理中。在3年时间里（2021年至2023年），记录了两种草地（草产量、植物组成、营养价值）和放牧动物（牛奶产量和组成、体重、体况评分）的生产性能。我们发现草地系统之间的牧草产量或草地营养价值没有显著差异，放牧季节长度也相似（264天）。在这3年的平均水平上，PRGWC - 125N含有150克/千克干物质的豆科植物，MSS - 125N含有160克/千克干物质的豆科植物、130克/千克干物质的车前草和40克/千克干物质的菊苣。PRG - 250N的个体奶牛牛奶产量和脂肪加蛋白质（乳固体）产量较低（分别为5018千克和452千克），PRGWC - 125N处于中间水平（分别为5139千克和463千克），MSS - 125N最高（分别为5297千克和476千克），而在研究期间，每公顷放牧的牛奶和乳固体产量相似（分别为11523千克/公顷和1016千克/公顷）。品种也有显著影响，与HF相比，JFX的牛奶产量较低，但脂肪和蛋白质浓度较高。这导致JFX每千克体重的乳固体产量高于HF（分别为0.96和0.87千克乳固体/千克体重）。本研究结果突出了更具多样性的牧场在减少化学氮肥投入需求、维持牧场生产力的同时提高基于牧场的春季产犊系统中动物生产性能的可能性。
