“Rumination is so sensitive to the cow’s state of being. Resting as a biological process, and rumination, are so closely intertwined,” Dr. Rick Grant, of the Miner Institute said. “Management that impairs lying time almost has to decrease rumination response,” no matter the diet being fed.
Rumination is impacted by external factors as well as internal rumen functioning. Rumination is the regurgitation of fibrous matter from the rumen to the mouth, and the return back to the rumen. This biological process is impacted by the forage’s nutritional and fiber content. Dietary fiber form and digestibility do play a role. Increasing feeding time and dry matter intake has a positive effect on rumination. Yet on any given diet, a cow will control rumination in response to external stressors.
The bulk of the cow’s ruminating time occurs in the evening. Low light, quiet environments, and a comfortable resting place are precursors to good rumination. Providing an environment conducive to maximizing rumination helps the cow to meet their natural need to ruminate. Just like humans and sleep, the optimal rumination time for cows is about eight or nine hours per day.
Cows simply prefer to ruminate lying down. Their favorite posture is sternal recumbency, with left-sided laterality, thought to position the rumen for best functioning. Because cows sleep for only short periods of time, rumination — which mimics deep sleep, producing similar physiological responses — is an important part of healthy dairy cow functioning.
“As managers, all we can do is mess that up and bring it down,” Grant said.
Rumination is not only a requirement for healthy cows; it can be a very early indicator of stress or illness. By monitoring decreases in rumination times, management changes can be made to alleviate stressful situations, or to begin treating a sick cow. Stress can be assessed via rumination decreases up to 48 hours prior to any other indicators being evident.
Deviations from the herd’s or the individual cow’s baseline rumination time is an early sign of some stressor. But rumination time is not measured by the percentage of cows lying down, Grant cautioned. While dividing the number of cows ruminating by the number of cows in the stall will give you an idea of cow comfort, it does not predict resting time and rumination, or assess changes in time spent ruminating from the baseline.
By creating an environment conducive to rumination, and keeping a close eye on any changes from the baseline rumination time, dairy herd managers can: spot illness early; assess the responses to any treatments; monitor the impact of environmental changes such as pen groupings; modify rations; and even spot cows in estrous. Looking at rumination can allow managers to spot problems before they become more extreme, and alter grouping strategies. Crowding, dominance and cow hierarchy, inability or hesitancy to lie down, and illness will all decrease rumination time.
“The more dominant cow is typically going to have more rumination activity,” Grant explained.
“Healthy cows clearly maintain higher rumination,” than so cows that will become ill after calving, Grant said.
Cows that have increased lying and ruminating times two to six days prepartum also show increased dry matter intake, and increased milk yield postpartum. While all cows will decrease rumination at parturition, it will increase again by about 50 minutes/day after calving. Cows who demonstrate low rumination after two to six days in milk are more likely to ultimately show clinical disease. Retrospectively, ill cows show a greater decrease in rumination, and this decrease lasts much longer after calving, than is seen in healthy cows.
During the first week postpartum, cows demonstrating high rumination times return to higher rumination levels more rapidly following calving than do those which demonstrated lower rumination times. Higher-rumination cows recover fully by three days in milk, while those ruminating less take 15 days in milk to reach the same rumination levels.
“Intense rumination through the transition period can be so important to the farm,” Grant said. “Healthy cows clearly maintain higher rumination. That’s tremendously economically important to the farmer.”
Rumination issues correlate to metabolic problems. Cows that develop issues within 30 days of calving demonstrate reduced rumination postpartum compared to healthy cows. Ketosis, abomasal displacement and indigestion all show symptomatically as reduced rumination time, sometimes several days before any other symptoms are apparent.
Indicator of other issues
Lameness is also predicted by decreases in rumination times. Rumination decreases occur 10 days prior to a diagnosis of lameness. While the correlation isn’t as clear as it is in metabolic issues, potentially monitoring rumination times, in conjunction with other indicators such as resting activity, could help managers spot lameness earlier.
Heat stress, too, shows up with reduced rumination times, prior to other symptoms being apparent. Cows will stand up to cool down, so rumination time decreases. By closely monitoring rumination, the environment can be adjusted for heat stress prior to any impact on milk production. High production cows, in particular, are very sensitive to changes in resting times.
“Rumination is really sensitive to the effectiveness of the heat abatement you have on your farm,” Grant said, so rumination monitoring can also help to gauge the effectiveness of various cooling systems.
Grant expects that rumination monitoring will become a practical tool, and a common one, on dairy farms moving forward. Because the cows’ rumination time is impacted early on, when under stress, it can provide the farmer with a simple tool to identify issues before they become a major concern. This will not only increase cow comfort and health, it can prevent needless culling and can keep milk production from dropping.
“The bottom line here is ‘earlier’,” Grant said.
Dr. Rick Grant of the Miner Institute presented this workshop at the 2015 Cornell Nutrition Conference, held in Syracuse, NY, Oct. 20-22.