Dairy NZ

Milking cows OAD in early lactation affects total lactation yield. This research is part of the DairyNZ Strategic Lactation Management Research Programme which aims to define optimum milking frequency and nutrition regimes, allowing farmers to make more informed decisions around management techniques that influence milk production.

Project Background

Two experiments were undertaken during the 2009/10 season. At DairyNZ's Lye Farm, milking OAD for three weeks immediately post-calving, milking OAD for six weeks immediately post calving and milking twice-a-day (TAD) throughout were compared. At WTARS in Taranaki cows were feed restricted for three weeks in early lactation to simulate a flood or severe weather with one herd milked OAD and one TAD.

Research Conclusions

This research has confirmed, under New Zealand conditions with New Zealand cows, evidence from previous overseas studies that showed that the longer you put cows onto OAD after calving, the greater the drop in immediate milk production followed by a subsequent carry-over loss.

Individual cows milked OAD for three weeks in early lactation produced 15% less milksolids (MS) during that period and 7% less total MS over the full season than cows milked TAD. This translates to a MS production decline of 4% over the full season in the situation where a herd is milked OAD for the first three weeks of calving. This equates to approximately $10,870 annual revenue lost per 100 cow herd (assuming 400kg mature cow MS and $6.50 per kg MS payout).

Trial cows milked OAD for six weeks after calving produced 12% less MS (on an annual basis) than those milked TAD.

Milking cows OAD during a feed restriction in early lactation reduced MS production by 50% more than the restriction alone in this trial, indicating that the negative effects of feed restriction and milking OAD are additive.

There was no difference in liveweight or BCS loss, submission rate, either three or six week in-calf rate, or final empty rate between those cows milked OAD or TAD.

Implications for farmers

Our advice to farmers is to be cautious. If you are going to milk OAD minimise the period of OAD and pay close attention to feed management throughout the season. This is vital to ensure the effects of OAD on milk production are minimised.