After three months of trials, cows receiving a molasses-based liquid supplement increased rumination time by 25 minutes per day on farm A (397 versus 422 minutes per day) compared to cows not receiving supplements. On farm B, cows receiving liquid supplements increased rumination time by 20 minutes per day (466 versus 486 minutes per day) compared to cows not receiving supplements during the first 40 days of lactation.
So why is rumination important? What are the implications of increased rumination?
What we know about the importance of rumination time is summarized below.
- Cows spend one-third of the day ruminating. Rumination facilitates digestion, particle size reduction and subsequent passage from the rumen. Rumination also stimulates saliva secretion, which may improve rumen pH and function.
- The time that cows spend ruminating is controlled by dietary and management factors such as fiber amount, particle size, degree of overcrowding, grouping strategies and other potential stressors in the management environment.
- Rumination time can be reduced by “non-ideal” environment and management factors.
- Rumination reflects cow health and is highly sensitive to the cow’s state of well-being. Cows have reduced rumination time when under acute or chronic stress.
- Rumination time responds to stressors 12 to 48 hours sooner than traditional measures, such as elevated body temperature, depressed feed intake and decreased milk yield.
- Cows prefer to ruminate while lying down: Greater than 90 percent of rumination occurs in stalls. A recent study reported that a 2 percent increase in resting was associated with a 7 percent increase in rumination. On the other hand, management that impairs lying down time also reduces rumination.
- Dominance hierarchy also affects rumination activity. Lower ranked cows ruminated 35 percent less than higher ranked cows, possibly due to shorter rumination bouts, lower feed intake and compromised well-being.
- Research shows that cows with greater lying and ruminating times a week before calving have greater dry matter intake and milk yield during the first two weeks after calving. Cows with less rumination before calving tend to have less rumination after calving. Shorter rumination time is associated with increased risk of metabolic disorders.
- Rumination time (minutes per day) changes in response to different events. Average rumination equals 450 to 550 minutes per day. Calving reduces rumination time by 170 to 255 minutes per day; estrus reduces rumination by 75 minutes per day; and mastitis reduces rumination by 40 to 120 minutes per day.
On-farm use of rumination monitoring can be beneficial for:
- Identifying nutritional problems
- Improving reproductive performance
- Detecting health problems earlier, such as metabolic disorders, mastitis and lameness
- Gauging management effectiveness on grouping and stocking density
- Changing treatment or culling decisions. Cows can be monitored after treatment to decide whether it is working or not.
Overall, given that rumination is highly sensitive to changes in cow health and comfort, increased rumination time by cows receiving molasses-based liquid supplements indicates that cows had better cow comfort and health status. This is consistent with the research findings from the two farms where cows receiving liquid supplements during the transition period had dramatically decreased incidence of fresh cow metabolic diseases and increased milk yield.
In short, monitoring rumination allows for earlier identification of problems and intervention. Feeding a molasses-based liquid supplement is an effective strategy to increase rumination time, an indicator of improved cow health and performance. 
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Kai Yuan
- Senior Research & Technical Adviser
- Quality Liquid Feed
