Chris Glassey, Roshean Woods, Charlotte Reed, Nauvoo Puriri, Gavin Scott, Alison Hodgkinson, Racheal Bryant
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引用次数: 0
摘要
新西兰奶农几乎没有关于其牛群饮食中剩余氮(N)的实时信息,以帮助管理农场规模的氮损失。通过了解管理对散装乳尿素(BMU)的影响,农民有可能利用乳成分来确定饲粮氮过剩的变化。本研究考察了在坎特伯雷和怀卡托选定的38个低或高BMU的奶牛场放牧管理与BMU浓度的关系。测定牧草在放牧前后的质量、多年生黑麦草在放牧期间的叶期、牧草的植物和化学成分(粗蛋白质(CP)和代谢能(ME)含量)。低BMU的牧群放牧前牧草量大(+153 kg DM/ha)、叶期早(+0.13叶数)、放牧间隔长(+11 d)。与此一致的是,低BMU农场的牧草CP低于高BMU农场(-2.7%)。我们确定了低和高BMU组之间放牧管理的差异,这可能与通过提供较低CP%的牧草减少牧群日粮中的N剩余有关。未来的工作应该确定这与其他农场管理因素(如补充和氮肥使用)的重要性。
Grazing management practices on Waikato and Canterbury dairy farms diverging in bulk milk urea content
New Zealand dairy farmers have little realtime information on surplus nitrogen (N) in their herd’s diet to help manage farm-scale N loss. By understanding the influence of management on bulk milk urea (BMU), farmers could potentially use milk components to identify changes in dietary N surplus. Our study examined the relationships between grazing management and BMU concentration on 38 dairy farms selected for low or high BMU in Canterbury and Waikato. Measurements included pre- and post-grazing herbage mass, perennial ryegrass leaf stage at grazing, and botanical and chemical composition (crude protein (CP) and metabolisable energy (ME) content) of herbage on four occasions over a year. Herds with Low BMU tended to graze pastures with a greater pre-grazing herbage mass (+153 kg DM/ha), a more advanced leaf stage (+0.13 number of leaves), and longer grazing intervals (+11 days). Consistent with this, herbage on Low BMU farms had lower CP (-2.7%) compared with High BMU farms. We identified grazing management differences between Low and High BMU groups, which could be linked to reductions in N surplus in the herd’s diet through the lower CP% of pasture offered. Future work should determine the importance of this in relation to other farm management factors such assupplement and N fertiliser use.