AABP members Dr. Ron Erskine and Dr. Roger Thomson discuss milk ejection with Dr. Fred Gingrich. Only 10% of the milk is in the cistern with the remainder requiring ejection from the alveolar component of the udder due to the effects of oxytocin. We discuss how a properly timed pre-milking routine can delay milk ejection and how this delay affects mouthpiece vacuum, teat end vacuum, and its associated affects on teat health. Milking routine not only can impact udder health, but also has implications for cattle well-being. Inappropriate mouthpiece and teat end vacuum causes pain and our guests discuss “interviewing the cow” by evaluating the teats, cow behavior, and residual milk volume with strip yields as an important evaluation step. We also discuss that bulk tank somatic cell count should not be utilized as a stand-alone metric for udder health and a holistic approach looking at records and parlor evaluations are a better system for identifying if there are concerns with milk ejection. Dr. Erskine references his research that demonstrated that proper milk ejection does not decrease unit on time but the savings is that cows that have delayed milk ejection (maximum milk flow rate more than one minute after unit attachment) produce 7 pounds less milk per milking. This research was presented at the 2019 AABP Annual Conference in the Research Summaries session. AABP members can access this recording through the AABP online CE portal by searching for the 2019 St. Louis Conference Research Summaries session or reviewing the proceedings paper titled “Effect of bi-modal milk letdown on milk production” at this link. 

 Relevant publications:

 Erskine RJ, Norby B, Neuder LM, Thomson RS. Decreased milk yield is associated with delayed milk ejection. J Dairy Sci. 2019 Jul;102(7):6477-6484. doi: 10.3168/jds.2018-16219. Epub 2019 Apr 25. PMID: 31030923.

 Moore-Foster R, Norby B, Schewe RL, Thomson R, Bartlett PC, Erskine RJ. Herd-level variables associated with delayed milk ejection in Michigan dairy herds. J Dairy Sci. 2019 Jan;102(1):696-705. doi: 10.3168/jds.2018-14561. Epub 2018 Oct 19. PMID: 30343911.

 Moore-Foster R, Norby B, Schewe RL, Thomson R, Bartlett PC, Erskine RJ. Herd-level variables associated with premilking stimulation time in Michigan dairy herds. J Dairy Sci. 2019 Mar;102(3):2544-2550. doi: 10.3168/jds.2018-14943. Epub 2019 Jan 11. PMID: 30639006