By: Anne Hardie

Milking frequencies are still evolving as farmers seek the best mix for staff, environment and logistics, with many now using a range of frequencies through a season.

LIC FarmWise consultant in the Top of the South, Brent Boyce, has produced a paper on the subject which looks at combining three milkings in two days (3in2), once-a-day (OAD) and twice-aday (TAD) milkings on dairy farms. He concludes there is still work to be done to understand how milking frequency can be adjusted and how the ever-evolving modern cow can be bred to achieve more milk from fewer milkings.

However, marginal analysis to date shows increased profitability if productivity is maintained and costs are reduced. Less-tangible benefits come into play as well such as reduced laminitis, improved condition score and reproductive results, as well as the human cost through fewer milkings.

He says there is a myriad of reasons for altering milking frequency on individual farms and sudden climatic changes can force a spot decision to move to 3in2 or OAD. If it occurs in early lactation before Christmas, the herd can simply return to TAD if conditions improve, while if it is later in the season, remain on the reduced milkings.

OAD in early spring reduces the workload and stress on staff and cows through that early calving period and modelling undertaken by DairyNZ estimates an entire herd milked OAD for two to three weeks from the planned start of calving will only reduce milk production for the season by 1-2%. That compares with a 7% loss for the whole season if every individual cow was milked OAD for their first three weeks of lactation. The benefits of OAD during this period improves cow energy status and body condition score (BCS), but only after five to six weeks from the cow first being milked OAD.

When using OAD over the mating period, Boyce says production losses will depend on the length of time on that regime and the level of feeding. Some farmers place all non-cycling cows on OAD at the start of mating, regardless of whether the cows are in good condition or not and even when feed is ideal, but he points out that some of those cows will be non-cycling due to an infection, laminitis, age, mastitis and social pressures.

He doesn’t recommend 3in2 over the mating period as the cows will continue to produce at high levels and it conflicts with timing for the AI technician. From observations over 17 years, he says the end of the five to six weeks of AI appears to be the earliest time in the lactation to change from TAD to 3in2 to avoid compromising production.

Post AI or Christmas, OAD and 3in2 come into play to avoid hot afternoon milkings, feed challenges, cow condition, declining production, slowing grazing rotation and using summer crops.

The drop in milkings also has staff and family benefits. DairyNZ’s work on OAD post-Christmas shows the cow’s production will drop by about 10% which equates to a 4% loss in production for the whole season when spread over the full lactation.

While cows produce 10% less milksolids, their feed intakes only drop 3%, with the extra energy given to weight gain. So the cow’s condition score is better at dry off than their TAD peers.

From observation, Boyce says farmers can expect the somatic cell count (SCC) to increase between 25,000 and 100,000 above the existing levels when switching to OAD mid-season.

Farmers switching from TAD to 3in2 at Christmas report little or no production loss and DairyNZ backs that as long as the milking interval is no more than 18 hours.

Boyce says a practical guide for choosing when to switch to 3in2 is when most of the cows are not leaking milk in the yard at the start of the morning milking.

“Farmers switching from TAD to 3in2 at Christmas report little or no production loss and DairyNZ backs that as long as the milking interval is no more than 18 hours.”

He says it is not necessary to alter the allocated areas grazed between the milking times when on 3in2 from Christmas to March.

From March onwards, the morning milking on day one should be the same time and the evening milking brought forward with the shorter daylight hours. This ensures the first cows milked can be sighted going to their paddock from the milking.

On day two, the mid-day milking needs to be brought forward if the time between milkings becomes too long from the morning milking. He says good rostering spreads night milkings between staff and gives everyone a sleep-in on day two.

Changing the frequency of milking throughout the season reduces time spent in the dairy for the farmer, staff and cows, which Boyce says adds up to big savings compared with TAD.

Extensive lactation data recorded across the Top of the South shows farms are producing between 350 and 400kg MS/cow from 304 milkings on farms milked OAD all season, equating to 1.15 to 1.30 MS harvested per milking. Farms milking TAD/OAD are producing 400 to 450 MS/cow, equating to 0.88 to 1.00 MS harvested per milking. While those on OAD/TAD/3in2/OAD have production levels between 440 and 495 MS/cow which equates to 0.93 to 1.02 MS harvested per milking.

Boyce says the latter farms are producing at similar or better levels than they did on TAD and with 100 to 125 fewer milkings per year.

Farmers will continue to evolve their systems, with 3in2, OAD and TAD all playing a role and he says the benefits enhance profitability and business sustainability.