Nicholson C F, Blake R W, Urbina C I, Lee D R, Fox D G, Van Soest P J
Department of Agricultural, Managerial, and Resource Economics, Cornell University, Ithaca, NY 14853.
J Anim Sci. 1994 Jul;72(7):1680-96. doi: 10.2527/1994.7271680x.
Objectives of this study were to compare three nutritional management strategies for dual-purpose herds in Venezuela in 1987 using a deterministic, multiperiod linear programming model of a representative farm. The model maximized discounted net margin (total revenues minus variable costs) from the herd for a 3-yr cow replacement cycle partitioned into six periods. The periods accounted for seasonal variation in forage availability and quality, and the model provided information about optimal animal inventories, animal sales, land in forage, and feed supplements. We compared current nutritional management practices and alternatives allowing optimal supplementation with commercial concentrate, molasses, cassava root, and urea. Iteration between the programming model and results from the Cornell Net Carbohydrate and Protein System assured technical coefficients consistent with predicted animal performance. Compared with management practices relying on commercial concentrate, optimal use of molasses and urea permitted increases in the stocking rate. Productivity and profit were restricted primarily by energy intake, which was constrained by intakes of NDF and DM. Alternative management strategies changed the relative importance of nutrient requirements and feed intake constraints. Thus, optimal interventions to alleviate nutritional constraints will vary with current management. Mobilizing adipose and protein tissues during lactation was optimal for most strategies. Supplementing with molasses and urea instead of commercial concentrate was the most profitable strategy, increasing herd net margin by 16% compared to the predominant feeding strategy in the late 1980s.
本研究的目的是使用一个具有代表性农场的确定性多周期线性规划模型，比较1987年委内瑞拉两用畜群的三种营养管理策略。该模型在一个分为六个时期的3年奶牛更新周期内，使畜群的贴现净利润（总收入减去可变成本）最大化。这些时期考虑了牧草可获得性和质量的季节性变化，该模型提供了有关最佳动物存栏量、动物销售、牧草用地和饲料补充剂的信息。我们比较了当前的营养管理做法以及允许用商业浓缩饲料、糖蜜、木薯根和尿素进行最佳补充的替代方案。编程模型与康奈尔净碳水化合物和蛋白质系统的结果之间的迭代确保了与预测动物性能一致的技术系数。与依赖商业浓缩饲料的管理做法相比，糖蜜和尿素的最佳使用允许提高饲养率。生产力和利润主要受能量摄入量的限制，而能量摄入量又受中性洗涤纤维和干物质摄入量的限制。替代管理策略改变了营养需求和采食量限制的相对重要性。因此，缓解营养限制的最佳干预措施将因当前管理而异。在大多数策略中，哺乳期动员脂肪和蛋白质组织是最佳的。用糖蜜和尿素而不是商业浓缩饲料进行补充是最有利可图的策略，与20世纪80年代后期的主要喂养策略相比，畜群净利润增加了16%。
