Lopez-Villalobos N, Garrick D J, Holmes C W, Blair H T, Spelman R J
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
J Dairy Sci. 2000 Jan;83(1):144-53. doi: 10.3168/jds.S0022-0302(00)74865-X.
The aim of this study was to evaluate the profitability of dairy herds under three mating systems involving the Holstein-Friesian, Jersey, and Ayrshire breeds. Mating systems were straight breeding and rotational cross-breeding using two or three breeds. A deterministic model was developed to simulate the nutritional, biological, and economic performance of dairy herds under New Zealand conditions. Expected performances per cow were obtained using estimates of breed group and heterosis effects, age effects, and age distribution in the herd. Requirements for dry matter in feed were estimated per cow for maintenance, lactation, pregnancy, and growth of the replacements. Stocking rate was calculated by assuming 12,000 kg of dry matter utilized annually per hectare. Productivity per hectare was calculated as performance per cow multiplied by stocking rate. Profitability was the difference between income (sale of milk and salvage value of animals) and costs (related to the number of cows in the herd and the land area farmed). Under current market values for milk and meat, all of the rotational crossbred herds showed superior profitability to the straightbred herds (Holstein-Friesian x Jersey, NZ$505/ha; Holstein-Friesian x Jersey x Ayrshire NZ$493/ha; Jersey x Ayrshire, NZ$466/ha; Holstein-Friesian x Ayrshire, NZ$430/ha; Jersey, NZ$430/ha; Holstein-Friesian, NZ$398/ha; and Ayrshire, NZ$338/ha). Changes in the value for fat relative to protein affected profitability more significantly in herds using the Jersey breed, and changes in the value for meat affected profitabiity more significantly in herds using the Holstein-Friesian and Ayrshire breeds. Results suggested that, under New Zealand conditions, the use of rotational crossbreeding systems could increase profitability of dairy herds under the conceivable market conditions.
本研究的目的是评估荷斯坦 - 弗里生牛、泽西牛和艾尔夏牛三个品种在三种配种系统下奶牛群的盈利能力。配种系统包括纯种繁育以及使用两个或三个品种的轮回杂交。开发了一个确定性模型来模拟新西兰条件下奶牛群的营养、生物学和经济性能。通过估计品种组和杂种优势效应、年龄效应以及牛群中的年龄分布来获得每头奶牛的预期性能。估算了每头奶牛维持、泌乳、怀孕和后备牛生长所需的干物质饲料量。通过假设每公顷每年利用12,000千克干物质来计算载畜率。每公顷生产力计算为每头奶牛的性能乘以载畜率。盈利能力是收入（牛奶销售和动物残值）与成本（与牛群中的奶牛数量和养殖土地面积相关）之间的差值。在当前牛奶和肉类的市场价值下，所有轮回杂交牛群的盈利能力均优于纯种牛群（荷斯坦 - 弗里生牛×泽西牛，505新西兰元/公顷；荷斯坦 - 弗里生牛×泽西牛×艾尔夏牛，493新西兰元/公顷；泽西牛×艾尔夏牛，466新西兰元/公顷；荷斯坦 - 弗里生牛×艾尔夏牛，430新西兰元/公顷；泽西牛，430新西兰元/公顷；荷斯坦 - 弗里生牛，398新西兰元/公顷；艾尔夏牛，338新西兰元/公顷）。脂肪与蛋白质价值的变化对使用泽西品种的牛群盈利能力影响更为显著，而肉类价值的变化对使用荷斯坦 - 弗里生牛和艾尔夏牛品种的牛群盈利能力影响更为显著。结果表明，在新西兰条件下，在可设想的市场条件下使用轮回杂交系统可以提高奶牛群的盈利能力。
