Mid-lactation once-a-day (OAD) milking

Late-season OAD experiment

Once-a-day (OAD) milking compared with twice-a-day (TAD) for three months in late lactation.

Key results

• 13% decrease in milksolids production while cows were on OAD

• Approximately a 5% decrease in milksolids at the season level

• ¼ body condition score (BCS) unit increase at dry off

• Approximately 2% decrease in dry matter intake

Experiment details and results

Details

Duration: January - end of lactation 2013

Cows: 52 Holstein-Friesian cows in two herds: Herd 1 milked twice a day (TAD), Herd 2 milked once a day (OAD)

Measurements:

• Cows feed intake
• Milk production
• Somatic cell count (SCC)
• Body condition score (BCS) gain

Results

Production:

• Production per cow dropped 13% while cows were being milked OAD.
• The 13% loss in milksolids production in this trial occurred when production was past its peak.
• Cows had already delivered about two-thirds of their season’s total yield.
• The overall impact on the season’s production was approximately 5%.

Feed intake:

• A small decline in feed intake.
• The decline in feed intake by the OAD herd was not as great as expected.
• Cows milked OAD ate about 2% less than cows milked TAD.

This small decrease in intake needs to be considered if milking OAD during a dry summer. Once-a-day milking will not solve a feed shortage problem. Although intake levels were similar, the OAD herd had a better energy balance because less energy was being put into milk production and walking. This resulted in OAD cows being on average a ¼ of a BCS unit more at dry-off than the TAD cows and therefore had less BCS to gain during the dry period to achieve calving BCS targets. BCS improvements take time; it wasn’t until after six weeks of OAD milking that there were detectable differences in BCS.

Somatic Cell Count and future lactations:

Although SCC was not greatly affected in this trial, it did increase in OAD cows as lactation progressed and milk volume decreased. The impact on SCC of switching cows to OAD milking in mid/late lactation needs to be considered, especially in the first few days.

To avoid grading when making the change to OAD the SCC needs to be able to double. Cows with high SCC or mastitis are not good candidates for OAD systems. Consider drying them off early. An option to prevent the large spike in SCC when switching, is to stagger it over a few days so they are not all spiking at the same time.

Cows that had been milked OAD were then followed into the next season where there was no reduction in milksolids yield when they commenced TAD milking again after calving. This disproves the 'mammary memory' myth that implies putting a cow on OAD will negatively impact future lactations.

These cows will likely have a higher BCS at dry-off, are more likely to reach the BCS targets at calving, and reap the production and reproduction benefits.

In this trial OAD milking did not extend the cows’ days in milk, cows were dried off individually based on their milk production and BCS. BCS was the deciding factor for drying off all the TAD milked cows (≤4.0), compared with the OAD herd which had 2 of 4 cows dried off due to production (<5 L/day for 5 days).

If contemplating milking OAD post-Christmas, these performance factors need to be considered alongside other farm-specific variables such as lifestyle and milking-associated costs.

You can access the full research article here.