Dahl Mohammad, Wieland Matthias
Department of Internal and Preventive Medicine, College of Veterinary Medicine, University of Mosul, Mosul 41002, Iraq.
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States of America.
Res Vet Sci. 2025 Feb;183:105510. doi: 10.1016/j.rvsc.2024.105510. Epub 2024 Dec 17.
Delayed milk ejection (DME) could compromise udder health and milking performance. The objectives of this systematic review and meta-analysis were to (i) explore the current evidence, assess the risk of bias, and identify the knowledge gaps in published studies that investigated the effect of DME on udder health and milking performance in dairy cows, and (ii) quantify the magnitude of the difference in milk yield per milking session (MY), milking duration (MD), and peak milk flow rate (PFR) between cows with and without DME. We performed the current systematic review and meta-analysis according to PRISMA 2020 statement. We tracked the pertinent peer-reviewed publications from PubMed using the following syntax (delayed milk ejection OR disturbed milk ejection OR bimodal milk flow OR bimodality) AND (bovine OR cattle OR cows), and additional relevant studies from the identified articles' reference lists. We calculated the pooled-mean difference in MY (kg), MD (seconds), and PFR (kg/min) between cows with and without DME using the random-effects models. The selection process identified 15 studies as the final number of studies qualified for review, including six interventional and nine observational studies published between 1980 and 2023 conducted in seven countries, including the USA, Germany, Italy, Switzerland, Netherlands, New Zealand, and Portugal. The results indicated that while the DME had a minimal influence on the udder health, it can reduce MY by 1.55 kg per milking session (95 % CI = -2.10, -1.00). The observed evidence here suggests that DME can negatively influence the milking profitability.
乳汁喷射延迟（DME）可能会损害乳房健康和挤奶性能。本系统评价和荟萃分析的目的是：（i）探索现有证据，评估偏倚风险，并确定已发表研究中关于DME对奶牛乳房健康和挤奶性能影响的知识空白；（ii）量化有或无DME的奶牛每次挤奶的产奶量（MY）、挤奶持续时间（MD）和峰值奶流率（PFR）之间差异的大小。我们根据PRISMA 2020声明进行了本次系统评价和荟萃分析。我们使用以下语法在PubMed上追踪相关的同行评审出版物：（乳汁喷射延迟或乳汁喷射紊乱或双峰奶流或双峰性） AND （牛或牛群或奶牛），并从已识别文章的参考文献列表中获取其他相关研究。我们使用随机效应模型计算有或无DME的奶牛在MY（千克）、MD（秒）和PFR（千克/分钟）方面的合并平均差异。筛选过程确定了15项研究作为最终符合评审条件的研究数量，包括1980年至2023年期间在七个国家（包括美国、德国、意大利、瑞士、荷兰、新西兰和葡萄牙）发表的六项干预性研究和九项观察性研究。结果表明，虽然DME对乳房健康影响极小，但它会使每次挤奶的产奶量减少1.55千克（95%CI = -2.10，-1.00）。此处观察到的证据表明，DME会对挤奶盈利能力产生负面影响。
