By Anne Lee

The idea of flexible milking times to create a three milkings over 48 hours schedule stems from an understanding of what’s going on at an udder level in terms of milk, fat and protein yield.

Research from the 1950s and 60s showed that milk accumulates in an approximately linear fashion until 16 hours after the last milking and after that it begins to decline.

Based on that information early adopters of the 3in2 milkings schedule stuck rigidly to the 16-hour milking intervals with milking carried out about 5am and 9pm on day one followed by only one milking the next day at 1pm.

This achieved a reduction in total milkings without unduly penalising milk production but the night milking was often unpopular.

Over time farmers evolved this to where a 12-18-18 hour interval is the most common. But the 12-hour interval can still make for a long day which is why DairyNZ added two more attractive times in year two of its flexible milking project to compare with OAD and TAD.

The three-in-two intervals included:

  • 12-18-18 hours
  • 10-19-19 hours
  • 8-20-20 hours

The rate of milk accumulation in terms of milk yield in the study followed a similar linear pattern as earlier studies with the decline coming in at milkings with longer intervals – beyond 16 hours.

Protein composition followed a similar trend to milk yield but fat continued at the same rate in a linear fashion showing no sign of declining even at the longer intervals tested.

There was a small but statistically insignificant difference in milksolids production between the three different 3in 2 intervals, indicating farmers can be more flexible in setting their milking times.

There was a small cost to both fat and total milk yield when there were consecutive long milking intervals.

Based on that knowledge farmers could consider altering milking times slightly so instead of even intervals in the longer situation the shorter interval could be followed by a slightly longer interval than the next – 8-22-18 for example – although this has not been investigated.