Do Swedish dairy cows need to sleep more?

22.12.2009 - (idw) Schwedischer Forschungsrat - The Swedish Research Council

Are Swedish dairy cows getting sufficient sleep? The exact duration of sleep a dairy cow needs is unknown today. However, new research at the Swedish University of Agricultural Sciences (SLU) aims at studying how much sleep a dairy cow needs and if there are any connections between the need for sleep and serious health problems such as mastitis and lack of energy early in lactation. It is well known that people need sufficient sleep in order to feel well. Research on humans and different animal species has shown that sleep deprived individuals use more energy than when they get sufficient sleep, but cows have not been studied. Today's high producing dairy cows are often housed in free stall systems where they are affected by the sounds and activity in their immediate vicinity throughout the day. This disturbance can reduce their possibility of obtaining a sufficient level of sleep.

-- We want to examine how much a Swedish dairy cow needs to sleep, says Dr Sigrid Agenäs, a researcher at the Department of Animal Nutrition and Management at SLU. Sleep deprivation can increase the energy requirement and decrease the immune function. The two major health problems in Swedish dairy production are mastitis and energy deficiency. Energy deficiency develops in early lactation when the animals are not able to eat enough to cover their daily energy need for milk production. Maybe sleep deprivation adds to this problem, says Sigrid.

In this two year study, funded by the Swedish research council Formas, the sleep pattern of dairy cows will be determined by the use of EEG (electroencephalography). This means that the electrical activity of the brain will be recorded. This method has previously been used on dairy calves in Finland but needs to be adapted and developed before it can be used on dairy cows.

-- When we have developed a good method we will combine EEG-measurements with behaviour recordings where we will examine how the animals behave in the barn. Thereafter will we analyse the relationship between the dairy cows' sleep pattern and their milk production, says Per Peetz Nielsen, also a researcher at the Department of Animal Nutrition and Management at SLU.

Previous research has shown that if you prevent animals from eating and lying down they prioritize to lie down before eating. Besides these behaviours the dairy cows spend time ruminating, waiting to be milked, being milked, drinking and on social behaviours.

-- There are reasons to believe that low ranking dairy cows have the highest level of sleep deprivation since, because of their low rank, they have to wait longer for access to the feeding area or to be milked, says Per.

To study sleep in dairy cows using non-invasive EEG measures is a new research area incorporating behaviour, health, physiology and animal welfare. Besides the effect on production the research group will also study the link between sleep and the dairy cows' immune defence. Research has shown that the immune defence is affected negatively by sleep deprivation.

At the end of this project the scientists will also develop a more simple method to measure sleep on dairy farms without expensive equipment. At present, there is a rule of thumb for the proportion of dairy cows in a herd that should be able to lie down at the same time. In the near future dairy farmers might even be able to evaluate if the cows are getting sufficient sleep!
For more information please contact:

Per Peetz Nielsen, phone: 018-67 48 16, e-mail:
Sigrid Agenäs, phone: 018-671633, e-mail: