Epsilon Open Archive

Abstract

Little is known about rest and sleep in dairy cows, but it has been shown in other species that the total amount of sleep, duration of sleep bouts and distribution of sleep over 24 hours differ depending on health status, age, pregnancy and lactation. Sleep recordings conducted on cows with surgically implanted electrodes have shown that they sleep four hours per 24-hour period.

In this thesis, a non-invasive electrophysiological technique for recording sleep in dairy cows was developed and used to investigate variations in sleep pattern
during the lactation cycle. Non-invasive sleep recordings and behaviour observations were conducted during five hours in eight cows to validate the recording method. The data was scored for sleep and awake states according to standardised methods for human sleep scoring and earlier findings on cow sleep. The behaviours ‘lying with head resting’ and ‘lying with head lifted and still’ were compared with sleep recordings in 13 cows to evaluate the accuracy of sleep time estimates based on behavioural indicators. To investigate whether the research equipment caused a first-night effect in sleep time in dairy cows, nine cows were studied over three consecutive 24-hour periods. Sleep was also recorded in 19 dairy cows on seven occasions to investigate variations in sleep time during a lactation cycle.

It was possible to distinguish sleep and awake states in data recorded with the non-invasive electrophysiological technique in unrestricted dairy cows. Using behaviour estimates only, sleep was greatly overestimated because
drowsing and sleeping can be performed in the same position. The electrophysiological recordings conducted during the first out of three consecutive 24-hour periods provide adequate data on total sleep time in dairy
cows.

In conclusion, the results show that cows sleep less and ruminate more in early and peak lactation compared with late lactation and dry period. Cows lie down to rest and it is therefore important to ensure that they have enough time to do so.