Animal Sciences Group, Wageningen University and Research Centre, Lelystad, the Netherlands.
J Dairy Sci. 2010 Mar;93(3):942-53. doi: 10.3168/jds.2009-2373.
The objective of this study was to quantify individual variation in daily milk yield and milking duration in response to the length of the milking interval and to assess the economic potential of using this individual variation to optimize the use of an automated milking system. Random coefficient models were used to describe the individual effects of milking interval on daily milk yield and milking duration. The random coefficient models were fitted on a data set consisting of 4,915 records of normal uninterrupted milkings collected from 311 cows kept in 5 separate herds for 1 wk. The estimated random parameters showed considerable variation between individuals within herds in milk yield and milking duration in response to milking interval. In the actual situation, the herd consisted of 60 cows and the automatic milking system operated at an occupation rate (OR) of 64%. When maximizing daily milk revenues per automated milking system by optimizing individual milking intervals, the average milking interval was reduced from 0.421 d to 0.400 d, the daily milk yield at the herd level was increased from 1,883 to 1,909 kg/d, and milk revenues increased from euro498 to euro507/d. If an OR of 85% could be reached with the same herd size, the optimal milking interval would decrease to 0.238 d, milk yield would increase to 1,997 kg/d, and milk revenues would increase to euro529/d. Consequently, more labor would be required for fetching the cows, and milking duration would increase. Alternatively, an OR of 85% could be achieved by increasing the herd size from 60 to 80 cows without decreasing the milking interval. Milk yield would then increase to 2,535 kg/d and milk revenues would increase to euro673/d. For practical implementation on farms, a dynamic approach is recommended, by which the parameter estimates regarding the effect of interval length on milk yield and the effect of milk yield on milking duration are updated regularly and also the milk production response to concentrate intake is taken into account.
本研究旨在量化奶牛在不同挤奶间隔下的日产奶量和挤奶时间的个体差异，并评估利用这种个体差异优化自动化挤奶系统使用的经济潜力。采用随机系数模型来描述挤奶间隔对日产奶量和挤奶时间的个体影响。该随机系数模型应用于由 311 头奶牛在 5 个不同牛群中 1 周内的正常连续挤奶 4915 次记录组成的数据组。所估计的随机参数显示，在不同牛群中，个体之间的产奶量和挤奶时间对挤奶间隔的反应存在显著差异。在实际情况下，牛群由 60 头奶牛组成，自动挤奶系统的占用率（OR）为 64%。通过优化个体挤奶间隔来使自动化挤奶系统的日奶收入最大化，平均挤奶间隔从 0.421 天减少到 0.400 天，牛群的日产奶量从 1883 千克增加到 1909 千克/天，奶收入从每天 498 欧元增加到 507 欧元。如果在相同的牛群规模下达到 85%的 OR，则最优挤奶间隔将降至 0.238 天，产奶量将增加到 1997 千克/天，奶收入将增加到 529 欧元/天。因此，需要更多的劳动力来驱赶奶牛，并且挤奶时间将增加。或者，通过将牛群规模从 60 头增加到 80 头而不减少挤奶间隔，也可以达到 85%的 OR。然后，产奶量将增加到 2535 千克/天，奶收入将增加到 673 欧元/天。对于农场的实际应用，建议采用动态方法，定期更新有关间隔长度对产奶量的影响和产奶量对挤奶时间的影响的参数估计值，并考虑到对浓缩饲料摄入的奶产量反应。
