Understanding Normal Milk Flow Patterns

Posted: January 4, 2006

Understanding milk flow patterns of individual and groups of cows can help you to evaluate how well people, cows, and equipment are doing in harvesting milk on your dairy.

Information that pinpoints when certain events occurred within a single cow milking, where they occurred (stall id), who was involved (person & cow id), and how much milk was produced over that time period (lbs. per second or per phase) can be very beneficial to understanding, monitoring and evaluating quality of the milking process.

This article describes the phases of optimal milk flow and briefly suggests reasons why milk flow can become abnormal. Practical ways of monitoring milk flow patterns to evaluate performance of people and equipment as well as importance of and reasons for abnormal milk flow patterns will be described in subsequent articles.

Monitoring systems can be used in both parlors and stanchions to capture this information. Automatic electronics and software systems make collection and
perhaps monitoring easier. This data can also be collected for periodic evaluation by trained consultants within milking facilities without data collection electronics. Quality of evaluation and recommendations are then based on the knowledge and skill of your consultant. The ability to apply recommendations to improve milking performance is the hard part and essential to either electronic or non-automated milking systems. This art is based on a trainer or supervisor’s ability to transfer his or her knowledge and skills and then to motivate employees to harvest high quality milk efficiently from each cow.

Figure 1 shows a picture of milk flow from the time the milking unit is attached until it is removed. Time that the milking unit is on a cow (Unit On-Time) is shown on the horizontal axis. Milk Flow (lbs. of milk produced) is shown on the vertical axis. The numbers in the black squares represent seconds into the cow’s milking from unit attachment to detachment. The numbers in triangles represent the unique phases of milk flow during a cow’s milking. The picture represents the milk flow rate or lbs. of milk produced per unit of time that the machine is attached until it is permanently detached from the cow’s udder. This milking rate is represented by the dark line. Milk flow is basically nonexistent when the unit is first attached, increases rapidly in a short time period (if oxytocin is released properly), reaches it’s highest level and remains steady for a period of time, declines rapidly, and then more slowly (milk dribble period) until the milking unit is removed from the cow manually or automatically when milk harvested per unit of time reaches a certain level. By dividing this entire period into five distinct phases, different aspects of the milking process which are affected by people, cow behavior, or equipment function can be monitored on your dairy.

Figure 1. Milk Flow Pattern of a High Producing and Properly Stimulated Dairy Cow

Milk Flow Pattern

  • Phase 1 represents the time period from when the claw vacuum is turned “ON” until oxytocin is released and milk flow is started. Phase 1 is frequently called ‘Delay Time from Attach to First Flow’. This time period should be relatively short. Milk prepping procedure, a cow’s fear of her environment with new surroundings, sore teats due to injury, mastitis or malfunctioning milking equipment, and mistreatment before and during milking may affect milk flow during this very important phase of milking.
  • Phase 2 represents the time period where milk flow increases rapidly within a short time period. This phase ends when lbs. of milk harvested per second stays high and fairly constant. The combination of Phase 1 and Phase 2 should last about 60 seconds. Phase 2 measures the interval from ‘First Flow to Peak Flow’.
  • Phase 3 represents the time period when a steady (constant) and high rate of milk is harvested for a period of time. Providing cows are prepped properly before the milking unit is attached, cows are healthy, and equipment is functioning properly, Phase 3 should be when most of the milk is harvested. This time period is also the time when there is the least stress to the cow’s teats. This phase is commonly called ‘Peak Flow’. A cow’s production level and times milked per day will also affect length of this phase.
  • Phase 4 represents the time period where milk harvested declines at a rapid rate. This period is often referred to as ‘Dropping Flow’.
  • Phase 5 is the final time and a crucial stage of the milk harvest process. It is commonly called the ‘Low or No Flow’ phase. There is usually a trickle or dribble of milk harvested until the individual teats are “dry” or contain a minimal amount of milk. A long Phase 5 is commonly known as ‘over milking’ and can affect teat health. Several factors that are controllable by the end of milking procedures of people and equipment can affect length of time a cow spends in Phase 5 of the milking process.

Sandra Costello, Sr. Extension Associate, Workforce Development & Milking
Penn State Dairy Alliance, Dairy Alliance is a Penn State Cooperative Extension Initiative