Department of Applied Economics and Management, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2009 Dec;92(12):6105-15. doi: 10.3168/jds.2009-2213.
The purpose of this paper was to identify effective dairy farm management adjustments related to recent structural changes in agricultural commodity markets because of expanded biofuels production and other market factors. We developed a mathematical programming model of a representative dairy farm in New York State to estimate the effects of changes in the relative prices of important feed components on farm profitability, identify optimal adjustments for on-farm feed production, crop sales, and dairy rations that account for expanded utilization of corn distillers dried grains with solubles (DDGS), and point out potential implications of these adjustments on whole-farm nutrient planning. We mapped out an effective farm-level demand curve for DDGS by varying DDGS prices relative to other primary feed ingredients, which allowed us to compare DDGS utilization at alternative market conditions. Had the relative prices of major feed ingredients remained at their historical averages, our results suggest that there is only modest potential for feeding DDGS through supplementation in rations for dry cows and heifers as a substitute for soybean meal. However, the relatively lower DDGS prices experienced in 2008 imply an expanded optimal use of DDGS to include rations for lactating cows at 10% of the total mixed ration. Despite these expanded opportunities for DDGS at lower prices, the effects on farm net returns were modest. The most important considerations are perhaps those related to changes in the phosphorus (P) levels in the dairy waste. We showed that including moderate levels of DDGS (10%) in rations for lactating cows did not significantly increase P excretion. However, if the rations for dry cows and heifers were supplemented with DDGS, P excretion did increase, resulting in sizable increases of plant-available phosphorus applied to cropland well beyond crop nutrient requirements. Although our results show that it is economically optimal for the dairy producer to incorporate DDGS into these rations, some operations will be unable to accommodate the additional P because of existing nutrient management recommendations, soil P status, and the number of acres available for manure spreading.
本文旨在确定与农业商品市场近期结构性变化相关的有效奶牛场管理调整措施，这些变化源于生物燃料生产的扩大和其他市场因素。我们开发了一个纽约州代表性奶牛场的数学规划模型，以估计重要饲料成分相对价格变化对农场盈利能力的影响，确定农场饲料生产、作物销售和奶牛日粮的最佳调整方案，以考虑到玉米干酒糟及其可溶物（DDGS）的利用扩大，并指出这些调整对整个农场养分规划的潜在影响。我们通过相对 DDGS 价格与其他主要饲料成分的变化，绘制了 DDGS 的有效农场需求曲线，这使我们能够在替代市场条件下比较 DDGS 的利用情况。如果主要饲料成分的相对价格仍保持在历史平均水平，我们的研究结果表明，通过在干奶牛和后备牛的日粮中添加 DDGS 作为替代豆粕来补充饲料的潜力不大。然而，2008 年相对较低的 DDGS 价格意味着可以扩大 DDGS 的最佳利用范围，将其包括在泌乳牛的日粮中，占总混合日粮的 10%。尽管在较低价格下有更多机会使用 DDGS，但对农场净收益的影响不大。最重要的考虑因素也许与奶牛废物中的磷（P）水平变化有关。我们表明，在泌乳牛的日粮中添加适量的 DDGS（10%）不会显著增加 P 的排泄量。然而，如果在干奶牛和后备牛的日粮中补充 DDGS，则 P 的排泄量会增加，导致施用到农田中的可利用磷大量增加，远远超过作物养分需求。尽管我们的研究结果表明，从经济角度来看，奶牛生产者将 DDGS 纳入这些日粮是最优的，但由于现有的养分管理建议、土壤 P 状况和可用于粪肥施用的耕地数量，一些养殖场无法容纳额外的 P。
