de Vries A, Conlin B J
Department of Animal Science, University of Minnesota, Saint Paul 55108, USA.
J Dairy Sci. 2003 Nov;86(11):3516-26. doi: 10.3168/jds.S0022-0302(03)73956-3.
Total economic effects of decreased estrus detection efficiency (EDE) are a function of the economic loss per day and the length of the decrease. A stochastic dynamic dairy herd simulation model was used to determine whether estimates from permanently different EDE rates in herds of 100 and 1000 cows could approximate net returns due to temporary decreases in EDE. The default EDE was 65% and was either permanently or temporarily decreased to 55, 45, or 35%. Temporary decreases in EDE were assumed to continue until identified using cumulative sum or Shewhart control charts. Marginal changes in net return were greater at lower permanent rates of EDE, with losses ranging from 0.73 to 1.24 dollars per extra day open. Temporary decreases in EDE typically yielded smaller effects on net return than permanent decreases, but estimates were not consistently significantly different. However, temporary (30 to 960 d) decreases in EDE affected projected herd economic performance for several years after EDE was reset to 65%. Total losses in net return due to temporary decreases in EDE ranged from 4.44 dollars (accepting more false alarms) to 12.53 dollars (fewer false alarms) per cow for the 100-cow herd. For the 1000-cow herd, total losses in net return ranged from 0.95 to 10.43 dollars per cow. Total losses were not dependent on magnitude of decreased EDE because lower EDE could be detected earlier, thereby compensating for higher daily losses; for example, 35% EDE resulted in lower total losses than 55% EDE. Decreases to 55% EDE were detected sooner by cumulative sum charts, whereas decreases to 35% EDE were detected earlier by Shewhart charts. Both control charts used together can identify unexpected decreases in EDE more efficiently, thereby minimizing potential economic losses.
发情检测效率降低（EDE）的总体经济影响是每日经济损失和降低时长的函数。采用随机动态奶牛群模拟模型，以确定100头和1000头奶牛的牛群中因EDE暂时降低而导致的永久不同EDE率估计值能否近似净收益。默认的EDE为65%，永久或暂时降至55%、45%或35%。假设EDE的暂时降低会持续，直到使用累积和或休哈特控制图识别出来。在较低的EDE永久率下，净收益的边际变化更大，每多一天未受孕的损失在0.73至1.24美元之间。EDE的暂时降低通常对净收益的影响小于永久降低，但估计值并非始终存在显著差异。然而，EDE暂时降低（30至960天）会在EDE重置为65%后的几年里影响预测的牛群经济表现。对于100头牛的牛群，由于EDE暂时降低导致的净收益总损失为每头牛4.44美元（接受更多误报）至12.53美元（接受更少误报）。对于1000头牛的牛群，净收益总损失为每头牛0.95至10.43美元。总损失不取决于EDE降低的幅度，因为较低的EDE能更早被检测到，从而弥补每日较高的损失；例如，EDE降至35%导致的总损失低于降至55%。累积和图能更快检测到EDE降至55%，而休哈特图能更早检测到EDE降至35%。同时使用这两种控制图能更有效地识别EDE的意外降低，从而将潜在经济损失降至最低。
