Once a day milking a practical option for summer dry conditions

DairyNZ recommends once a day (OAD) milking as a key option in managing cow demand for feed during dry summer conditions when pasture quality and quantity often limit cow performance.

“Get the balance right,” says DairyNZ senior farm systems scientist Dr Dawn Dalley. “It is far better to plan to go OAD before feed runs short than to be forced into it by a severe shortage of feed.

“OAD or 16 hourly milking are good options to take the pressure off cows when summer feed supply is limited, especially if cows are walking long distances to be milked. OAD can also reduce stress on staff, and free time to do other tasks such as feeding out.”

Research in Taranaki on part-season OAD milking has shown that after switching to OAD in mid-January, cows gained 0.2 - 0.4 BCS units by dry off, whilst cows which remained on twice a day milking only increased condition score after drying off. Post Christmas OAD will reduce the stress and energy used by cows walking to the shed and if implemented correctly can have a minimal impact on milk production.

“Average per cow milk production may be used as a trigger to determine when cows can be milked OAD”, says Dawn. “The trigger will depend on the breed, BW, and the range of per cow production in the herd as some low producing cows may dry themselves off.

“In the Taranaki trials, milking high genetic merit Jersey cows, the trigger used to start milking OAD was average herd production of 1.2 kg MS/cow. Where these cows were well fed the drop in production was only 0.1- 0.15 kgMS/cow/day.

“The drop in milk production depends on the level of production and is greater where cows are eating low quality feed. Trials have shown that if cows are producing an average of 0.85 kgMS/cow/day OAD milking will cause little or no reduction in milk yield for the majority of the herd, so long as feed quality and quantity is maintained. Cows producing more than 1.2 kg MS/cow/day may experience a small drop in production of between 5-10%.”

Milking OAD for a period over summer when feed supplies are limited will help to:

• Achieve BCS and pasture cover targets later in the season, so that cows are dried-off and calve in good condition, thereby minimising negative effects on next season’s performance because of the present season’s feed shortage • Maximise days in milk by avoiding drying cows off in summer or being forced to dry cows off early because they have very low BCS. The farm should have more cows fit to milk to a later date once feed conditions improve than if twice a day milking had been continued • Ensure the optimum level of profitability without compromising next season’s reproductive performance, milksolid production and cow welfare.

Dawn advises that milking OAD in summer will decrease total cow feed demand by up to 10%. “If this does not look like being enough to balance feed supply and demand then other actions (culling or drying some cows off, accepting greater body condition loss or buying in feed) will need to be done in conjunction with OAD,” she says. “All of the herd, light condition cows or just the young cows, which are most at risk can be milked OAD.

“During the transition to OAD it is critical to manage feeding well: maintain feed quality and quantity at twice a day levels for at least the first week. If MS/cow drops by 0.2 kg/day or more, this indicates that cow requirements are not being met. Underfeeding during the transition to OAD may exacerbate SCC issues as the somatic cells will be concentrated in a smaller volume of milk.”

DairyNZ’s predecessor Dexcel undertook trials at WTARS in Taranaki which showed that the bulk SCC will rise during the first 24-48 hours of OAD as the udder adjusts to less frequent milking. “Generally SCC concentrations stabilise within a week,” says Dawn. “Often a high bulk SCC is caused by a few cows with persistently high cell counts.”

Milking all cows OAD might not be an option if the bulk SCC is over 220,000. “If there is any doubt on cell counts, schedule a herd test just prior to going OAD or check the whole herd with a paddle/rapid mastitis test,” says Dawn. “The cows identified with mastitis can be dried-off or culled to decrease overall feed demand or continue to be milked twice a day. Once the cell count for the rest of the herd has stabilised it may be possible to gradually put higher cell count cows onto OAD, but this can only be successful if careful monitoring is done. Attention to detail during milking is critical, especially just after going OAD. Check for swollen quarters or cows which are not milking-out well.”

For more information on the seasonal management of mastitis and milking OAD visit the Tight Management pages on the DairyNZ website: www.dairynz.co.nz/tightmanagement

ENDS

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