Department of Animal Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2012 Mar;95(3):1170-6. doi: 10.3168/jds.2011-4388.
Premilking udder preparation (including forestripping and duration of lag time-the time between first tactile stimulation and attachment of milking unit) might influence milking measures such as milking unit on-time, incidence of bimodality, and milk flow rates in Holstein cows milked 3 times daily. Holstein cows (n=786) from an 1,800-cow commercial dairy herd were enrolled under a restricted randomized design to determine the effect of 9 different premilking routines. Lag times were 0, 60, 90, 120, and 240s and included forestripping or no forestripping for a total of 9 treatments (no forestripping for 0 lag time); the study was conducted from February to November 2008. All cow-treatment combinations were compared with the control: predipping plus forestripping and drying with 90s of lag time. Cows were initially assigned to 1 of 3 treatments for a period of 7d and upon completion of the first 7-d period were reassigned to a different treatment until all treatments had been completed. From one treatment period to the next, cows had to switch stimulation method with no restriction on lag time. Cows did not receive all treatments during the duration of the trial. Early- to mid-lactation cows (EML; 17-167 DIM) and late-lactation cows (LL; 174-428 DIM) were housed in 2 different pens. Milk yield was significantly different between dip + forestrip and dip+dry for 2 of the treatments for EML cows compared with dip + forestrip and 90 s of lag-time (DF90); however, this was not thought to be due to treatment because the significant lag times were very different (60 and 240 s) and neither was an extreme value. Milk yield did not differ with treatment for the LL cows. Milking unit on-time did not differ when comparing all treatments for EML with treatment DF90; however, an increase in milking unit on-time occurred when lag time was 60s or less for LL cows. The highest incidence of bimodal milk curves was when lag time = 0 and this was independent of stage of lactation; a lag time of 240 s had the second-highest incidence of bimodal milk curves for EML and LL cows. Milk harvested in the first 2 min was lower for lag times of 0 and 240 s when compared with DF90. Increasing the lag time for all cows appeared to improve overall milking time efficiency (although lag time had no effect on EML cows).
预挤奶前乳房准备（包括擦洗和延迟时间-第一次触摸刺激到挤奶装置连接之间的时间）可能会影响挤奶措施，如按时挤奶、双峰模式发生率和荷斯坦奶牛的奶流量，这些奶牛每天挤奶 3 次。在一项受限制的随机设计中，从一个拥有 1800 头奶牛的商业奶牛场招募了 786 头荷斯坦奶牛，以确定 9 种不同预挤奶方案的效果。延迟时间为 0、60、90、120 和 240 秒，包括擦洗或不擦洗，总共有 9 种处理（0 延迟时间不擦洗）；该研究于 2008 年 2 月至 11 月进行。所有奶牛-处理组合均与对照组进行比较：预擦洗加擦洗，干燥，延迟时间为 90 秒。奶牛最初被分配到 3 种处理中的 1 种，持续 7 天，在完成第一个 7 天周期后，被重新分配到另一种处理，直到所有处理都完成。从一个处理周期到下一个处理周期，奶牛必须切换刺激方法，延迟时间不受限制。在试验期间，奶牛没有接受所有处理。早中期泌乳牛（EML；17-167 DIM）和晚期泌乳牛（LL；174-428 DIM）被安置在 2 个不同的畜栏中。与预擦洗+90 秒延迟时间（DF90）相比，2 种 EML 奶牛的处理中，擦洗+预擦洗与擦洗+干燥的产奶量有显著差异，但这并不是由于处理，因为显著的延迟时间非常不同（60 和 240 秒），而且都不是极值。对于 LL 奶牛，产奶量与处理无关。与 EML 相比，所有处理的挤奶装置按时完成率都没有差异，但对于 LL 奶牛，当延迟时间为 60 秒或更短时，挤奶装置按时完成率会增加。当延迟时间=0 时，双峰奶曲线的发生率最高，且与泌乳阶段无关；对于 EML 和 LL 奶牛，延迟时间为 240 秒时，双峰奶曲线的发生率第二高。与 DF90 相比，延迟时间为 0 和 240 秒时，前 2 分钟采集的奶量较低。所有奶牛的延迟时间增加似乎都提高了整体挤奶时间效率（尽管延迟时间对 EML 奶牛没有影响）。
