Rumination ruminations and sleep
We know that rumination is highly influenced by the amount of physically effective fiber (peNDF) a dairy cow consumes. The amount of NDF, particle length and digestibility all affect how long she needs to chew on that fiber. We also know that some things can depress rumination such as illness and anxiety. Sick cows stop ruminating and nervous cows stop ruminating. This made me wonder if rumination is a good indicator of cow comfort. Cows at ease, lying or standing will ruminate in the classic lazy dozing state while cows at dis-ease or ill-at-ease do not.
We were conducting “cow watch” for a trial comparing forage digestibility and monitoring chewing behavior and it struck me that cows will ruminate in the holding pen and milking parlor, and even in headlocks, if they feel comfortable. When they are not at ease they don’t ruminate. Could monitoring rumination in these situations indicate cows comfort with the facilities and routine and even people; vet, breeder, milkers? Even cows in highly over-stocked barns can be seen ruminating. Do these situations account for the anomalies of healthy, high-production cows in overstocked situations? Even though there may be no stall space to lie down, if ruminating while standing, can we assume the cows are still comfortable, at ease?
This made me wonder about the notion that cows are in a state of “sleep” when they are in the classic drowsy state of rumination. We all know the health benefits of adequate sleep on metabolism, immunity and endocrine system in people, the same must hold true for cows. Between sufficient sleep and rumination can we monitor or improve overall cow health?
Not much is known about cow sleep. Researchers in Finland are testing a non-invasive EEG (electroencephalography) technique to monitor brain activity of cows. Past technology involved restrained animals and invasive electrical implants. The new technology involves external “snap-on” electrode sensors placed on the cow’s forehead. Early indications are that this is a valid method to monitor brain wave patterns. The researchers indicate that cow sleep is divided into 3 types of brain wave patterns; drowsing, NREM (non-rapid eye movement; head up but motionless) and REM (rapid eye movement; head back on body or ground, not supported by neck), in contrast to awake patterns. Cows sleep in many intervals throughout the day, and that total sleep time is only about 3 hours/day of NREM and 45 minutes/day of REM with about 6 hours/day of drowsing. It’s not clear if the drowsing state is synonymous with rumination. The authors state that in humans this drowsy state is simply transitional period from wake to sleep but in cattle it is longer and the significance of this period is not yet understood.
I will be watching more closely not just to how many cows are ruminating post meal but the situations where they are and are not ruminating to discern if there are stress points in their lives that can be alleviated. It may be that rumination can tell us more about animal well-being than simply if we have enough peNDF in the diet to maintain rumen well-being.
Article by Kurt Cotanch, Miner Institute
Ternman, E. et al. 2012. Sleep in dairy cows recorded with a non-invasive EEG technique. Applied Animal Behaviour Science. 140:25-32.