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Tasmanian Institute of Agriculture

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Published: 11 Apr 2019

Milking cows rotary dairy

Lesley Irvine, TIA

Anyone can see that milking once-a-day has its attractions, but is it a profitable option? At the 2019 Tasmanian Dairy Conference, Paul Edwards from DairyNZ presented the results from two recent studies comparing twice-a-day (TAD) milking systems to once-a-day (OAD) milking systems.

Milking regime















OAD (12%)

Switch TAD/OAD3



Tactical OAD

Switch Other4




1Whole-herd, full-season

2Part-herd, full-season

3Whole-herd, part-season

4Part-hard, part-season

The studies focused on strategic OAD milking – that is, farms that milked their herd OAD for the whole season.

Production difference

One of the studies compared 302 OAD herds and 2424 TAD herds. The study paired the OAD herds with similar TAD. It showed there was an 11% decrease in milk production in the first year of milking OAD. Milk production returned to the pre-OAD milk production level by the fourth year of OAD milking. However, compared to their paired TAD milking herds, OAD milking herds were still 11% behind the TAD herds as the TAD herds had also increased production during the four years. There was less of a production impact on the lower producing OAD herds.

OAD milking slide

Reproductive performance

Given that OAD milking results in lower milk production, to retain profit parity with TAD herds, there must be benefits that improve profitability and/or cost reduction for OAD herds. There are several ways this can occur:

  • Improved reproductive performance – OAD had tighter calving spreads
  • While replacement rates were the same between OAD and TAD herds at 20%, the reasons cows were culled were different
    • Less cows were culled because they were empty in OAD herds
    • More cows were culled because of low production and udder reasons (e.g. blind quarters, mastitis, cell count, slow milker, udder breakdown) in OAD herds

Economic performance

The second study compared New Zealand DairyBase data from 2005/06 to 2015/16. This data included 99 OAD herds and 927 TAD herds. The data showed OAD herds did not reduce costs relative to TAD herds and had decreased profitability relative to TAD herds.

The greatest opportunity to reduce costs in OAD herds is with labour as you are only milking once-a-day. Labour also accounts for over 20% of costs on a dairy farm. However the study showed there was only a very small increase in the cows milked per full time equivalent on OAD farms.

Key messages

Paul’s key messages about OAD milking from the two studies were:

  • A decrease in milk production of 2-16% is likely in the first year. Herds with existing low per cow milk production have the lowest decrease in production. The decrease in milk production will be greater in higher producing herds.
  • Costs need to be reduced to maintain or improve profitability but on average this wasn’t achieved.
  • If target costs aren’t achieved it doesn’t mean OAD milking is unprofitable (just might be less profitable than equivalent TAD herd).
  • There are many drivers for adopting OAD.
  • It is important to examine the systems changes and prepare a budget if considering OAD.