Rumination data

Rumination or chewing the cud is a vital part of a cow’s digestion. It helps break down fibrous feed, supports healthy rumen function, and improves nutrient absorption. With wearable technology, farmers can now track rumination time across the herd in real-time, offering new insights into cow behaviour, feed quality, and overall performance. Learn what rumination data means, what’s normal, what affects it, and how to use it to make better decisions on-farm.

• Rumination is a behavioural signal, not a diagnosis.
• Feed type, quality and quantity are the biggest drivers.
• Rumination data can support decisions but not replace stockmanship skills.
• Focus on feeding your cows well, monitoring trends, and managing at-risk cows.
• Always interpret rumination alongside feed quality and availability, management changes, cow behaviour and health, and environmental conditions.

What is rumination and what’s normal?

When a cow eats, she only partially chews the grass before swallowing. Later she regurgitates that feed and chews it again - this is the process of rumination. It increases the surface area of feed particles, making them easier for rumen microbes to digest.

Rumination supports digestion and nutrient absorption. It helps maintain a healthy rumen pH and indicates how well cows are functioning.

Typical rumination time

• Herd average: 7 to 8 hours/day
• Individual range: 2.5 to 10.5 hours/day
• More rumination at night than during the day

Rumination varies throughout the day and is influenced by feed type, pasture allocation, and cow behaviour. Some devices show daily totals while others show hourly patterns. Both can be useful.

Focus on trends, not numbers

Rumination values can vary widely between cows, herds, and devices. What matters most is how it changes over time- not aiming for a specific target.

• Know what’s normal for your herd
• Watch for sudden drops or unusual patterns
• Always interpret rumination alongside other data (feed, health, management changes, weather)

What affects rumination time?

Not all devices report the same numbers. A DairyNZ study showed that cows wearing three different devices (neck collar, rumen bolus, ear tag) had different rumination values, however, the patterns were similar. This is mostly due to different algorithms, different reporting styles (hourly vs rolling average) and different placement on the cow.

A DairyNZ study fitted 100 cows with three different rumination sensors, one on the neck, one in the rumen (bolus), and one on the ear. These cows were monitored for 20 days to compare how each device reported rumination time.

Although all three devices were tracking the same cows, the rumination values reported were different. The patterns were similar, though, for example, when rumination dropped on one device, it usually dropped on the others too.

The study did not manually observe cows’ behaviour while they ruminated, so it was not possible to say which device gave the most accurate number. However, it’s more useful to focus on the direction and size of changes over time rather than the exact value.

Comparing your results with other farms may be misleading. Instead, focus on your own baseline data and track changes over time to assess whether the technology is supporting your goals.

Calving and rumination

Rumination behaviour is predictable around calving. It typically drops sharply just before and during calving, then gradually recovers over the following one to two weeks. However, the speed and pattern of recovery can vary from cow to cow.

This graph shows the average rumination time for 333 three-year-old cows grazing on pasture from 35 days before to 35 days after calving. Cows were milked TAD. The dark green line represents the herd average, while the shaded area shows the range where 50% of cows’ rumination values sit, highlighting normal variation within a herd.

Does more feed equal more rumination?

It’s easy to assume that more feed means more rumination, but that’s not always the case. Cows eating high-quality, highly digestible feed may spend less time ruminating because the feed breaks down more quickly in the rumen. This means rumination time doesn’t always reflect how much a cow is eating; it’s more about the type and quality of the feed.

Seasonal changes in pasture quality also play a role. As pasture digestibility shifts throughout the year, rumination patterns can change. For example, summer pasture tends to be more fibrous and takes longer to break down, which can increase rumination time. In contrast, lush spring pasture may reduce rumination time because it’s easier to digest.

How and when pasture is offered also influences rumination. Offering the same total pasture allocation once or four times a day doesn’t significantly change the total daily rumination time, but it does affect when cows ruminate. Cows may ruminate more at night or between grazing sessions, depending on how feed is allocated.

To get the most out of rumination data, it’s important to monitor pasture cover and post-grazing residuals. These indicators help ensure cows are getting enough energy from the feed on offer, which supports both rumination and overall performance.

Feed type

• High-fibre feeds (e.g. hay, summer pasture) = more rumination (if total DMI is the same or greater per cow)
• Low-fibre feeds (e.g. chicory, plantain, concentrates) = less rumination (if total DMI is the same or less per cow)
  • If the addition of concentrates increases the total DMI, rumination time may increase

How weather can affect rumination

Weather conditions can have an impact on rumination behaviour. During periods of rain and cooler temperatures, cows may ruminate more, but this may occur while standing or grouped as an attempt to preserve body heat. In contrast, windy conditions may reduce rumination time, as cows are more likely to be unsettled. Extreme weather events, such as storms or sudden temperature changes, can cause rumination to drop sharply. This usually happens when cows stop eating or change their grazing behaviour in response to the conditions. If rumination data shows a sudden dip, it’s worth considering if weather might be the cause before assuming there’s a health issue.

Health alerts

Wearables may trigger health alerts based on sudden drops in rumination or changes in other behaviours depending on the device. These alerts are designed to help you spot potential health issues early but they’re not perfect. A DairyNZ report showed sensitivity (how often alerts catch real problems) is moderate (around 70–75%, meaning about 1 in 4 cows with an issue might not trigger an alert). It’s important to understand what these alerts mean, how reliable they are, and what to do when one pops up. Keep in mind that rumination can also drop naturally during oestrus events (heat), which some technologies factor into their algorithms to avoid false positives.

If everything looks normal and the cow is eating, walking, and milking well, it might be a false alert. But if something seems off, it’s worth investigating further. Always check cows physically and interpret data alongside other signs.

Alerts can be triggered by:

• Difficult calving
• Mastitis
• Metabolic disease (e.g. milk fever, clinical ketosis)
• A weather event
• A change in feed

Wearables and reproduction

In addition to supporting cow health and nutrition, wearable data can play a role in reproductive performance, particularly through heat detection. Learn more about how wearables contribute to managing herd reproduction.