Early lactation once-a-day (OAD) milking

A short period (≤ six weeks) of once-a-day (OAD) milking during the calving period reduces workload and allows more time for other tasks on-farm. However, research suggests it has short and long terms effects on milk production.

Key considerations for early lactation once-a-day milking

• Milking individual cows OAD for as little as three weeks immediately after calving reduces whole-lactation milksolids (MS) yield.
• The total production loss depends upon the duration of OAD and is due to both immediate and long-term reductions in daily milksolids (MS) yield.
• Milking OAD post-calving improves cow energy status, but body condition score is not improved until five to six weeks in milk.
• Milking cows OAD during a temporary feed shortage in early lactation decreases milksolids (MS) yield by more than the feed restriction on its own.
• While OAD milking improves cow energy status during a feed restriction, it does not prevent BCS loss.
• Although OAD milking reduces potential milksolids (MS) production, it allows farmers more time to focus on other important management issues. Depending upon the individual farm system, the benefits from getting these management decisions right could offset the negative effects of OAD on cow milk production.

Benefits of early lactation once-a-day 

• Reduced workload during the peak season.
• Improved cow health.
• Better cow energy status (indicated by blood metabolites and hormones).
• Gradual improvement in body condition score as a result of the better energy status.

Challenges of early lactation once-a-day 

Reduced kgMS/cow/day for the season, even after returning to twice-a-day milking.

• Herd OAD for 3 weeks from planned start of calving: 1-2% less kgMS for the season.
• Herd OAD for 6 weeks from planned start of calving: 3-5% less kgMS for the season.
• Cow OAD for 3 weeks post-calving: ~7% less kgMS for the season.
• Cow OAD for 6 weeks post-calving: ~12% less kgMS for the season.

Strategies to maximise the labour benefits of milking OAD while minimising the loss of milk revenue include:

• Milking the herd once-a-day for a set time from the planned start of calving (variation in OAD time for different cows) as shown in Figure 1, or
• Once-a-day milking during the colostrum period (e.g., every cow is OAD for their first one to two weeks post-calving) as shown in Figure 2.

Figure 1: OAD milking for a set period e.g., OAD for the first 3 weeks of calving regardless of how long individual cows get.

Figure 2: OAD milking for a set time for each cow from calving.

Early lactation once-a-day researach in pasture-based systems

A study was carried out on DairyNZ’s Lye Farm in 2009/10 with 150 mixed age, Holstein -Friesian x Jersey cows, separated into five groups.

• Group 1: milking twice-a-day (TAD) for the entire lactation.
• Group 2: milked OAD for 3 weeks immediately after calving and TAD thereafter.
• Group 3: milked OAD for 6 weeks immediately after calving and TAD thereafter.
• Group 4: milked 3X a day for three weeks immediately after calving and TAD thereafter.
• Group 5: milked 3X a day for six weeks immediately after calving and TAD thereafter.

Cows were offered a generous pasture allowance of 30-40 kg DM/cow/day (target post-grazing residuals of 1800 kg DM/ha). They were also fed 2 kg DM/cow/day of concentrates (13 MJ ME/kg DM) for two weeks pre-calving; 4 kg DM/cow per day from calving (July) to November; followed by 2 kg DM/cow per day until mid-November, and pasture only thereafter.

Body condition score loss during the first four weeks post-calving was similar between cows milked OAD and TAD.

• By five-six weeks in milk, cows milked OAD had a greater BCS (~0.2 units).
• By late lactation, the differences were negligible (see Figure 2 below).
• Previous research has found that longer durations of OAD milking following calving will achieve greater improvements in BCS.

Post-calving milking frequency did not affect reproductive performance. Cows temporarily milked OAD or three times (3X) a day post-calving had similar anoestrous intervals and submission, conception, and pregnancy rates to those milked TAD, agreeing with previous research on short-term effects of milking frequency.

Thus, the differences in energy status and BCS were not sufficient to alter reproduction in this experiment. It remains unclear from this work if short-term early-lactation OAD milking can improve reproduction when cows calve below target BCS and/or are underfed, causing poor BCS during early lactation. Anecdotal evidence from South Island herds suggests short term use of OAD has a beneficial effect on reproductive performance.

Read the full article here.

Farm systems implications of milking once-a-day for a short period

At the farm level, several approaches can minimise the total milksolids loss when using short-term OAD milking in the immediate post-calving period. Confining OAD milking to the colostrum period only or milking the whole herd OAD for a set period, such as three weeks from the planned start of calving, may be useful.

Milking the herd OAD for a set time period (like figure 1 above) reduces milk production loss as more cows have shorter OAD milking duration as calving progresses (as opposed to a set time per cow).

Models predict that milking the herd OAD for three or six weeks from the planned start of calving and then TAD thereafter will reduce annual farm MS production by 1-2% or 3-5%, respectively. Milking OAD during the colostrum period only (i.e., eight milkings) and then TAD thereafter will reduce MS production by about 2%.

Example of milk revenue loss

300 cow herd producing 350kg MS/cow/year: 2% loss of milksolids production at $6.00/kg MS

• 2% of 350kg MS/cow/year = 7kg MS/cow/year
• 7kg MS/cow/year* 300 cows = 2,100kg MS/year
• 2,100kg MS/year * $6.00/kg MS
• = $12,600 reduction in milk revenue

This example only looks at milk revenue loss, it does not consider savings made or other benefits such as reproduction, which can increase profitability.

A herd-based OAD milking strategy is likely to be more effective at reducing workload and improving farmer/worker stress during calving. Less time spent on milking-related activities may save labour costs. In addition, more time is available for other tasks (e.g., grazing management, animal health, etc.).

If these areas are managed more effectively, any positive effects on animal husbandry and, therefore, milk production may partially compensate for the negative effects of OAD milking.

Once-a-day milking during a feed shortage in early lactation

In pasture-based dairy systems, extreme weather events such as floods, heavy snowfall, or storms can result in severe feed shortages that will negatively impact not only milk production but also reproduction and animal welfare.

If there is an acute feed shortage in early lactation careful consideration should be given to the consequences of once-a-day (OAD) milking as a management strategy, including financial impact.

It is likely more profitable to supplement feed than to use OAD milking to reduce feed demand and BCS loss.

Pros and cons of OAD milking during a feed shortage in early lactation

• Allows more time to spend on non-milking activities such as supplement feeding and pasture management, or repairs in the case of a natural disaster.

• Can reduce stress on people during a difficult period.

• If supplementary feed is delayed or unavailable, once-a-day may reduce the risk of metabolic disorders, improve cow energy status and potentially improve reproduction.

• Results in additional losses in milksolids production.

• Does not reduce feed demand.

• Does not alleviate body condition score loss.

Acute feed deficit study

120 mixed age (≥3 years) Holstein-Friesian and cross-bred cows, at ~five weeks post calving.

Put into four groups for a three-week period:

1. Fed and milked twice-a-day (TAD)
2. Fed and milked once-a-day (OAD)
3. Underfed by 40% and milked twice-a-day (TAD)
4. Underfed by 40% and milked once-a-day (OAD)

Figure 1 (below) shows cows that were underfed and milked twice-a-day produced 9% less milksolids over the season, and cows that were underfed and milked once-a-day produced 13% less milksolids over the season.

Figure 1. Milksolids (MS) yield from cows fed to recommended levels (FED) or underfed (UF) and milked either twice (2X) or once-daily (1X). The three-week treatment period is represented by the shaded area.

Figure 2 (below) shows that in underfed cows milked twice-a-day, blood concentration of β-hydroxybutyrate exceeded 2mmol/L putting them at risk of clinical ketosis. It also shows a lower risk of ketosis when underfed cows are milked once-a-day. Average β-hydroxybutyrate concentrations did not exceed 1 mmol/L.

Figure 2. β-hydroxybutyrate concentrations of cows fed to recommended levels (FED) or underfed (UF) and milked either twice (2X) or once-daily (1X). The three-week treatment period is represented by the shaded area.

Figure 3 (below) shows cows milked once-a-day during a feed deficit still lost ~0.2 BCS units during the 3-week feed shortage - the same as cows milked twice-a-day and underfed. The lack of an effect of once-a-day milking on BCS loss in underfed cows may be because BCS is a relatively crude measure of energy status and three weeks may not have been long enough to detect subtle changes in energy stores using this method.

Figure 3. Body condition score (BCS) of cows fed to recommended levels (FED) or underfed (UF) and milked either twice (2X) or once-daily (1X). The three-week treatment period is represented by the shaded area.

Read the full research article here.

Supporting research from Ireland

A 2021 study was carried out in Ireland with 4 test groups.

1. TAD - control group
2. OAD4 - 4 weeks of OAD milking after calving, TAD for the remainder of the season
3. OAD6 - 6 weeks of OAD milking after calving, TAD for the remainder of the season
4. OAD8 - 8 weeks of OAD milking after calving, TAD for the remainder of the season

The key findings in this study were:

• Milking cows once daily for six or eight weeks in early lactation reduces milk yield.
• Milking time was up to 35% less when cows were milked once-a-day.
• From week five of lactation, somatic cell score was similar between treatments.

This study is consistent with the New Zealand research, indicating about a 0.8% per week impact to milksolids production and therefore ~1% reduction in total kgMS/cow for the season if milking OAD for the colostrum period.

Read the full research article here.