What do we know about rumination?
Below are the summary notes adapted from an article titled “Biological importance of rumination and its use on farm” written by Drs. Ric Grant and Heather Dann from Miner Research Institute, Chazy, NY.
Cows spent one-third of the day ruminating. Rumination facilitates digestion, particle size reduction, and subsequent passage from the rumen thereby influencing dry matter intake. Rumination also stimulates salivary secretion and improves ruminal function via buffering
Rumination is controlled by dietary and management factors such as fiber amount and particle size, degree of overcrowding, grouping strategies, and other potential stressors in the management environment.
Cows and nutritional factors (such as dry matter intake, fiber content, particle size, and digestibility) set “ideal” maximum time on rumination. Rumination time can be reduced by “non-ideal” environment and management factors.
Rumination reflects cow health and is highly sensitive to the state of well-being. Cows voluntarily control rumination and stop when disturbed. Cows have depressed rumination activity under acute and 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. Deviation from baseline rumination is sign that rumen function is negatively affected.
A wide range of management factors may depress rumination activity including overcrowding, mixed parity pens, excessive time spent in headlocks, and heat stress. If rumination is chronically depressed by 10 to 20% due to poor management, then we can reasonably predict compromised ruminal function and greater risk for associated problems such as sub-acute rumen acidosis, poorer digestive efficiency, lameness, and lower milk fat and protein output.
Cows prefer to ruminate while lying down: > 90% of rumination occurs in stalls. A recent study reported that 2% increase in resting was associated with 7% increase in rumination. On the other hand, management that impairs lying time also reduces rumination.
When cows are fed the same diet, as stall and headlock stocking density is varied from 100 to 142%, rumination time drops by 24 min/d, rumination while standing increases by 36 min/d, while recumbent rumination decreases 54 min/d.
Dominance hierarchy also affects rumination activity. Lower ranked cows ruminated 35% less than higher ranked cows, possibly due to: shorter rumination bouts, lower feed intake by low-ranking cows, and compromised well-being.
In transition dairy cows, rumination normally decreases by about 70% at parturition and increases by approximately 50 min/d following calving. Research showed that cows with greater lying and ruminating times a week before calving have greater DMI 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.
Changes in rumination time in response to different events: average rumination: 450 to 550 min/d; calving: -170 to -255 min/d; estrus: -75 min/d; heat stress: -20 to -70 min/d; mastitis: -40 to -120 min/d.
On-farm use of rumination monitoring: (1) identifying nutritional problems; (2) improving reproductive performance; (3) detecting health problems earlier such as metabolic disorders, mastitis, and lameness; (4) gauging management effectiveness: grouping and stocking density; (5) modifying traditional fresh-cow checks with fewer disturbances of cows and time in headlocks, less labor, and more focus on high-risk cows; (6) changing treatment culling decisions: cows can be monitored after treatment to decide whether it is working or not.
Overall, rumination is highly sensitive to changes in cow health and comfort. Monitoring rumination allows earlier identification of problems and intervention, earlier gauging of effectiveness of management, and earlier assessment of treatment effectiveness.
