Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Co. Cork, P61 C997, Ireland; Department of Chemical and Life Sciences, Waterford Institute of Technology, Waterford, X91 K0EK, Ireland.
Department of Chemical and Life Sciences, Waterford Institute of Technology, Waterford, X91 K0EK, Ireland.
J Dairy Sci. 2021 Aug;104(8):8870-8884. doi: 10.3168/jds.2020-19898. Epub 2021 May 21.
The objective of this systems-scale study was to investigate grazing season timeframes on pasture and milk production and on milk processability of dairy systems with compact spring-calving dairy cows grazing white clover (Trifolium repens L.) based grassland. Fifty-four primiparous and multiparous Holstein-Friesian dairy cows were used in a one-factor study with 3 systems (n = 18) and repeated over 2 yr (2008/09 and 2009/10). The 3 systems were: early spring calving with annual fertilizer N input of 100 kg·ha applied in spring (ES100N; 2.1 cows·ha; grazing February to November), early spring calving without fertilizer N (ES0N; 1.6 cows·ha; grazing February to November) and late spring calving without fertilizer N (LS0N; 1.53 cows·ha; grazing April to January). Annual pasture production was affected by an interaction between grazing system and year: Mean annual pasture yields for 2008 and 2009 were ES100N; 10.35 and 9.88, ES0N; 8.88 and 8.63, LS0N; 9.18 and 10.31 t of dry matter (DM)·ha (SEM 0.39). LS0N had higher pasture DM yield in 2009 due to higher clover DM production and biological N fixation compared with the other systems. Clover stolon and root mass in the following February was correlated with stolon and root mass in the previous November with 64% of stolon mass present on LS0N in February (R = 0.84). There were no detectable differences in per-lactation milk yield (6,335 kg·cow), fat, protein and lactose yields (271, 226, 297 kg·cow, respectively), cow liveweight (585 kg) or body condition score (3.02). Although winter grazing favored subsequent clover DM production, biological N fixation and pasture DM production, delaying calving date in spring and extending lactation into the following winter led to inefficient use of this pasture by the grazing herd and lowered the quality of late-lactation milk for processing purposes. Hence, a mean calving date in mid- to late-February is recommended for zero-fertilizer N input clover-based grassland.
本系统规模研究的目的是调查在春季短日照条件下，以白三叶草（Trifolium repens L.）为基础的草地放牧的奶牛牧场和牛奶产量以及牛奶加工性能的放牧时间框架。在一项为期 2 年（2008/09 和 2009/10）的单因素研究中，使用了 54 头初产和经产荷斯坦-弗里森奶牛，分为 3 个系统（n = 18）。这 3 个系统是：春季施氮 100 公斤/公顷的早春产奶牛（ES100N；2.1 头/公顷；2 月至 11 月放牧）、不施氮的早春产奶牛（ES0N；1.6 头/公顷；2 月至 11 月放牧）和不施氮的晚春产奶牛（LS0N；1.53 头/公顷；4 月至 1 月放牧）。年度牧场产量受到放牧系统和年份的相互作用影响：2008 年和 2009 年的平均年牧场产量分别为 ES100N；10.35 和 9.88，ES0N；8.88 和 8.63，LS0N；9.18 和 10.31 吨干物质（DM）/公顷（SEM 0.39）。LS0N 在 2009 年的牧场 DM 产量较高，因为与其他系统相比，它的三叶草 DM 产量和生物固氮量更高。第二年二月的匍匐茎和根质量与前一年十一月的匍匐茎和根质量相关，LS0N 二月的匍匐茎质量中有 64%（R = 0.84）来自前一年十一月。泌乳期内的牛奶产量（6335 公斤/奶牛）、脂肪、蛋白质和乳糖产量（271、226、297 公斤/奶牛）、奶牛活重（585 公斤）或体况评分（3.02）均无显著差异。虽然冬季放牧有利于随后的三叶草 DM 产量、生物固氮和牧场 DM 产量，但春季产犊日期的推迟和随后冬季泌乳期的延长导致放牧牛群对这种牧场的利用效率降低，并降低了加工后期泌乳牛奶的质量。因此，建议在 2 月中旬至下旬为无氮肥输入的三叶草草地推荐平均产犊日期。
