PDF(Pubmed)
Abstract：
The primary objective was to investigate the association between delayed milk ejection (DME) and the average milk flow rate, milking unit-on time, and duration in a low milk flow rate in Holstein dairy cows in a large dairy herd with suboptimal premilking teat stimulation. Our second objective was to study the association between peak lactation milk yield and the occurrence of DME. This longitudinal field study was conducted at a 4300-cow dairy farm with a thrice-daily milking schedule over a 1-week period. We analyzed data from 61,677 cow milking observations from 2937 cows. Delayed milk ejection was defined as present if the 30-60 s milk flow rate was ≤3.1 kg/min. The mean average milk flow rate (MAMF, kg/min), mean milking unit-on time (MMUT, s), and mean duration of a low milk flow rate (MLMF, s) were calculated as the mean values from the 21 milking observations. General linear multivariable models revealed associations of DME with MAMF, MMUT, and MLMF. A multivariable ordinal logistic regression model revealed an association between peak lactation milk yield and DME. Cows with lower peak lactation milk yield had greater odds of exhibiting a higher frequency level of DME. The observed associations between DME and milking performance indices suggest that DME can negatively affect milking and parlor efficiency. Peak lactation milk yield may serve as a proxy to estimate cows\' risk of recurrent DME. Future research is warranted to test if alleviating DME through, for example, a modified milking routine influences the milking performance indices described herein.
摘要：
主要目的是调查延迟排奶（DME）与平均牛奶流速之间的关系，挤奶单位时间，在大型奶牛群中，荷斯坦奶牛的牛奶流量较低，挤奶前乳头刺激欠佳。我们的第二个目的是研究泌乳峰值产奶量与DME发生之间的关系。这项纵向田间研究是在一个4300头奶牛的奶牛场进行的，在1周内每天进行三次挤奶。我们分析了来自2937头奶牛的61,677头奶牛挤奶观察结果的数据。如果30-60s牛奶流速≤3.1kg/min,则将延迟的牛奶排出定义为存在。平均牛奶流量(MAMF，kg/min),平均挤奶单位时间(MMUT，s),和低奶流量的平均持续时间(MLMF，s）计算为21次挤奶观察的平均值。一般线性多变量模型揭示了DME与MAMF的关联，MMUT,MLMF。多变量有序逻辑回归模型揭示了泌乳峰值产奶量与DME之间的关联。泌乳峰值产奶量较低的奶牛表现出更高的DME频率水平的可能性更大。观察到的DME与挤奶性能指标之间的关联表明，DME会对挤奶和客厅效率产生负面影响。泌乳峰值产奶量可以作为估计奶牛复发DME风险的替代指标。未来的研究有必要测试是否通过以下方式缓解二甲醚，例如,修改的挤奶程序影响本文所述的挤奶性能指标。
