Milk production per cow has risen severalfold over the past century, driven by advances in genetics, nutrition, animal health, and farm management. While this represents significant progress, it has also increased the demands placed on the modern dairy cow, particularly as she transitions from pregnancy to lactation.
A cow’s ability to cope with these demands depends greatly on how well she is prepared during the dry period.
Speaking at the 12th annual DMC Hollard Conference, held recently near Durbanville in the Western Cape, veterinarian and CowManager performance specialist Dr Marco de Groot compared the modern dairy cow to an elite athlete.
“The dry period is like a cow’s pre-season, and calving is her Rugby World Cup final,” he said.
Just as an athlete’s performance on match day depends on the preparation that comes before, a cow’s ability to cope with calving and early lactation is shaped by what happens while she is dry.
Poor feed or water intake, heat stress, overcrowding, and chronic pain can undermine that preparation and deplete the reserves she needs after calving, often before obvious signs of illness appear.
“A dry cow needs a fully charged battery to cope with the enormous metabolic, physical, and immune [system] demands,” De Groot said.
Transition alerts
Behaviour-monitoring technology, such as CowManager, can help farmers detect this ‘battery drain’ earlier by identifying subtle changes in a cow’s normal routine.
The CowManager ear sensor monitors eating, rumination, activity, and ear temperature. It generates a transition alert when a dry cow’s combined behaviour falls more than one standard deviation below the average for her group.
“A transition alert is a risk alert for dry cows,” De Groot explained.
“Cows with these alerts are more likely to develop health alerts after calving.”
An alert doesn’t confirm illness but signals a change that warrants investigation. In an individual cow, this may reflect reduced rumen function, mild inflammation, pain, or chronic stress.
When alerts increase across a group, farmers should examine possible environment- or management-related causes, such as heat stress, overcrowding, inconsistent feeding, inadequate access to water, or frequent group movement.
What the data shows
According to data that De Groot presented, more than 42% of monitored dry cows worldwide generated at least one transition alert, compared with about 40% in South Africa. More than 72% of cows that caused alerts during the dry period subsequently generated health alerts after calving.
German veterinarian and researcher Dr Stefan Borchardt examined this relationship using CowManager and herd-management records collected from a high-production dairy herd in Germany between April 2023 and April 2025. The dataset included 1 123 first-lactation cows and 2 257 cows in their second or subsequent lactation.
Borchardt compared cows that recorded no alert days, one alert day, or two or more alert days during the dry period. Older cows were found to generate more alerts than first-lactation animals and experienced the greatest consequences when alerts persisted.
Alerts were associated with higher rates of dystocia, stillbirth, retained foetal membranes, metritis, milk fever, and displaced abomasum. Alerted cows were also culled earlier in lactation, while older cows with two or more alert days produced less milk.
The production loss was substantial. At a milk price of R7,5/ℓ, De Groot valued the average shortfall per transition-alert cow at about R2 500, equivalent to roughly 333ℓ of milk during the lactation.
The total financial impact could be considerably higher, as this estimate excluded delayed reproduction, premature culling, veterinary treatment, medicine, and additional labour.
De Groot said these poorer outcomes may partly reflect the effects of sustained reductions in eating and rumination before calving. Affected cows may enter lactation with poorer rumen function and begin drawing on their body reserves sooner, deepening the negative energy balance and reducing their ability to cope with the metabolic and immune demands after calving.
“What you have before calving is what you’ll get after calving,” he added.
Three farms, three practical changes
To show how behavioural data could guide day-to-day management, De Groot shared three examples from commercial farms he had visited.
- Improving water access
In the first example, close-up cows on a German dairy were housed in an older building with a low ceiling, one water trough, and a dead-end corner. De Groot said this restricted the cows’ access to water and increased competition between them.
The farm added a second trough and created an outside extension, which also removed the dead end. After the changes, water intake increased, competition declined, and the number of transition alerts decreased.
De Groot noted that alerts rose again during periods of summer heat stress, but the overall improvement indicated that limited water access had contributed to the original problem.
- Feeding more frequently
The second example came from a Dutch farm where the dry cows were fed only once every two days. CowManager’s group data showed repeated periods when eating and rumination declined while inactivity rose.
De Groot said that a decline in eating isn’t necessarily concerning if rumination continues, as the cow may still be processing feed already consumed. However, when eating and rumination both decline while inactivity increases, it may indicate an empty feed bunk, unpalatable feed, or inadequate rumen fill.
CowManager flags these sustained changes, which may last several hours, as low-feed-intake alerts. At herd level, fewer low-feed-intake alerts are generally accompanied by fewer transition alerts.
The farm changed from feeding the cows every second day to feeding them daily. This provided fresher feed and reduced the number of low-feed-intake alerts in the dry-cow group.
- Reducing movement stress
In the third example, cows were moved directly from a cubicle barn into a large, straw-bedded close-up group. De Groot said the abrupt change in environment and social structure led to more competition, greater inactivity, and an increase in transition alerts.
Look beyond the individual cow
As working benchmarks, De Groot said that no more than 5% of dry cows should generate a transition alert on any given day.
Similarly, health alerts should affect no more than 5% of cows during the first 30 days in milk (DIM), while more than half of the herd should show signs of their first oestrus between eight and 42 DIM.
De Groot said the timing of low-feed-intake alerts may be more informative than the total number recorded.
Alerts occurring at roughly the same time each day may indicate a gap in feed availability, while a recurring weekly pattern could point to inconsistent feeding or staff routines. An increase in these alerts after cows have been moved may expose social stress, overcrowding, or unsuitable housing.
Examining these patterns can help farmers identify where and when problems arise and determine whether management changes improve the cows’ behaviour.
De Groot advised farmers to introduce changes separately. This makes it easier to determine which intervention produced the improvement and avoids exposing dry cows to several changes simultaneously.
“My takeaway for you is to limit the number of pen moves as far as possible and ensure that dry cows always have feed available. Even small interventions may lead to fewer transition alerts,” he concluded.
For more information, email Dr Marco de Groot at [email protected].
