Once-a-day milking

The main effect of permanent once a day milking (OAD) is a reduction in daily milk yield per cow, at least initially, resulting in reduced feed demand by cows and hence reduced greenhouse gas emissions.

The economic impact of any reduced production is often compensated by reduced input costs, particularly labour. The effect on profitability depends strongly on pay-outs for milk solids and reductions in labour costs. In addition, the effect on production, emissions and profitability is likely to change over time, as farms adapt to OAD and adjust the genetic make-up of their herd.

A big risk from an emissions perspective is that any reductions in emissions are short-lived. Farmers operating OAD systems will often increase stocking rate and/or increase imported feed and/or increase the rotation length. All of these things could counter the emission reduction gains made. Selection for cows suited to OAD may mean that, over time, OAD cows increase their feed demand and return to their previous productivity levels.

From a profit perspective, decreased milk revenues must be matched by cost savings; this will be more difficult when milk pay-outs are high.

Modelling indicates that this approach (with the qualifications noted above) could reduce emissions by 6–7%. However, how OAD is implemented will influence this. It's critical to start by finding out what your on-farm greenhouse gas emissions are.

For more information, see: 

• The DairyNZ website
• The LIC website
• Page 55 of this report by NZAGRC for the Biological Emissions Reference Group (BERG) in 2018