Neal M, Neal J, Fulkerson W J
Risk and Sustainable Management Group, University of Queensland, St. Lucia, Queensland 4072, Australia.
J Dairy Sci. 2007 Jun;90(6):3044-59. doi: 10.3168/jds.2006-645.
Although several forage species such as perennial ryegrass are predominant, there is a wide range of forage species that could be grown in subtropical and temperate regions in Australia as dairy pastures. These species have differing seasonal patterns of growth, nutrient quality, and water-use efficiency, as demonstrated in a large experiment evaluating over 30 species at the University of Sydney (Camden, New South Wales, Australia). Some species can be grazed, whereas others require mechanical harvesting, which incurs a further cost. Previous comparisons of species that relied on yield of dry matter per unit of some input (typically land or water) did not simultaneously take into account the season in which forage is produced, or other factors related to the costs of production and delivery to the cows. To effectively compare the profitability of individual species, or combinations of species, requires the use of a whole-farm, multiperiod model. Linear programming was used to find the most profitable mix of forage species for an irrigated dairy farm in a warm temperate irrigation region of New South Wales, Australia. It was concluded that for a typical farmer facing the prevailing milk and purchased feed prices with average milk production per cow, the most profitable mix of species would include a large proportion of perennial ryegrass (Lolium perenne) and prairie grass (Bromus willdenowii). The result was robust to changes in seasonal milk pricing and a move from year-round to a more seasonal calving pattern.
尽管多年生黑麦草等几种牧草品种占主导地位，但在澳大利亚亚热带和温带地区，仍有多种牧草品种可作为奶牛牧场种植。这些品种在生长季节模式、营养品质和水分利用效率方面存在差异，悉尼大学（位于澳大利亚新南威尔士州坎登）进行的一项评估30多个品种的大型实验证明了这一点。一些品种可以放牧，而其他品种则需要机械收割，这会产生额外成本。以往对品种的比较依赖于单位某种投入（通常是土地或水）的干物质产量，没有同时考虑牧草生产的季节，或与生产成本和向奶牛供应成本相关的其他因素。为了有效比较单个品种或品种组合的盈利能力，需要使用全农场多时期模型。线性规划被用于为澳大利亚新南威尔士州一个温暖温带灌溉地区的一家灌溉奶牛场找到最有利可图的牧草品种组合。得出的结论是，对于一个面临当前牛奶和购买饲料价格且每头奶牛平均产奶量的典型农场主来说，最有利可图的品种组合将包括很大比例的多年生黑麦草（Lolium perenne）和草原草（Bromus willdenowii）。该结果对于季节性牛奶定价的变化以及从全年产犊模式转变为更具季节性的产犊模式具有稳健性。
