Abstract High yielding crops such as maize (Zea mays L.) and fodder beet (FB; Beta vulgaris L), are commonly used to extend lactation and increase animal productivity from pastoral dairy systems. Financial modelling to compare costs and benefits of different crops is useful for decision making, but such modelling often fails to account for potential animal health risks which can be associated with feeding supplements. A multi-component, whole-farm modelling approach was used to predict milk solids (MS, milk fat + protein) production and the economic farm surplus (EFS: operating surplus – adjustments) between 2016 and 2018 for an irrigated farm in Canterbury (South Island) and a non-irrigated farm in the Waikato (North Island), of New Zealand. The financial risk of the dairy business was measured using the ratio between mean return on assets (ROA) minus an assumed 5% risk-free ROA, and the standard deviation of ROA was calculated from 300 combinations of climate, milk, and feed price, land appreciation, and interest rate. Four scenarios of autumn and spring supplementation of pasture were considered at each geographical location; imported maize silage (Base), a crop of maize silage grown on the milking platform (MSC; area used to produce milk), a crop of FB grown on the milking platform (FBC), and a FB crop with an outbreak of acute (1% stock fatality) and subacute ruminal acidosis (5% decline of feed intake) across the entire herd (FBAC). The MSC scenario improved EFS by 5.8% compared with Base in both the irrigated and the dryland system. The predicted response to MSC reflected greater milk production, lower feed expenses, and shorter crop rotation, compared with either Base, FBC, or FBAC. While FBC increased EFS by 4.8% compared with Base under irrigation, EFS was similar to Base under dryland conditions ($2711 and $2759/ha, respectively). The limited advantage of growing FB under dryland conditions reflect reduced herbage supply due to the extended crop duration of FB compared with maize silage. Model predictions suggest that FBAC will increase the financial risk by reducing milk production and EFS by 6.5% (irrigated) and 7.1% (dryland) compared with Base. In the absence of any adverse health risks, farm performance from the FBC scenario was comparable to that of MSC under irrigated conditions. However, in dryland conditions, and when the potential economic cost of acute and sub-acute ruminal acidosis is considered, there is little advantage to growing FB on the milking platform.

中文翻译：

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饲料甜菜支持牧场早期和晚期泌乳的牛奶生产，是否值得冒险？

摘要 高产作物，如玉米 (Zea mays L.) 和饲料甜菜 (FB; Beta vulgaris L)，通常用于延长牧区奶牛系统的泌乳期和提高动物生产力。比较不同作物的成本和收益的财务模型对于决策很有用，但这种模型通常无法考虑可能与饲料补充剂相关的潜在动物健康风险。2016 年至 2018 年间，坎特伯雷（南部）灌溉农场的乳固体（MS、乳脂 + 蛋白质）产量和经济农场盈余（EFS：运营盈余 - 调整）采用多组分、全农场建模方法进行预测。岛）和新西兰怀卡托（北岛）的一个非灌溉农场。乳制品企业的财务风险是使用平均资产回报率 (ROA) 减去假设的 5% 无风险 ROA 之间的比率来衡量的，并且 ROA 的标准偏差是根据气候、牛奶和饲料价格的 300 种组合计算得出的，土地升值和利率。每个地理位置考虑了秋季和春季补充牧草的四种情景；进口玉米青贮饲料（基础），在挤奶平台（MSC；用于生产牛奶的区域）上种植的玉米青贮作物，在挤奶平台（FBC）上种植的一种FB作物，以及一种爆发急性（ 1% 的牲畜死亡率）和亚急性瘤胃酸中毒（采食量下降 5%）在整个畜群 (FBAC)。在灌溉和旱地系统中，MSC 情景与 Base 相比将 EFS 提高了 5.8%。与 Base、FBC 或 FBAC 相比，对 MSC 的预测反应反映了更高的牛奶产量、更低的饲料费用和更短的作物轮作。虽然 FBC 与灌溉条件下的 Base 相比将 EFS 提高了 4.8%，但 EFS 与旱地条件下的 Base 相似（分别为 2711 美元和 2759 美元/公顷）。在旱地条件下种植 FB 的有限优势反映了与玉米青贮相比，由于 FB 的作物持续时间延长，牧草供应减少。模型预测表明，与 Base 相比，FBAC 将通过将牛奶产量和 EFS 减少 6.5%（灌溉）和 7.1%（旱地）来增加财务风险。在没有任何不利健康风险的情况下，FBC 情景中的农场性能与灌溉条件下的 MSC 性能相当。然而，在旱地条件下，