Epsilon Archive for Student Projects

Abstract

The aim of this project was to quantify the total sleep time in modern dairy cows during
24-hour periods and to investigate whether the total amount of sleep as well as time
spent in different sleep stages varies between the dry period, early- and peak lactation.
The distribution of sleep time between night and day was also examined. Furthermore,
correlations between sleep and lying time, fluctuations in body temperature and heart
beat were included in the aim. Eight dairy cows of the Swedish Red breed were used in
this study, which was carried out between June and September 2010. In order to
quantify sleep non-invasive electrophysiological recordings were performed.
Simultaneously with collecting sleep data, body position and body temperature were
also recorded. No heart rate data was obtained due to difficulties of maintaining
electrodes for heart beat measurements attached to the skin. One 24-hour data
collection was performed on each cow in the three different stages of lactation. The
electrophysiological data was visually scored according to definitions of human sleep.
Electrophysiological data from one of the eight cows mainly contained artefacts and all
her data was excluded from the data set. Shorter sleep time was obtained in early- and
peak lactation compared with the dry period. The rapid eye movement (REM) sleep time
and REM sleep time in proportion of total sleep was higher in peak lactation compared
to early lactation. It could also be concluded that cows sleep during larger proportion of
the night compared with the day. Indications of a possible correlation between total
sleep time and total lying time was found, but no relationship between sleep and
fluctuations in body temperature. Possible correlations between sleep and heart beat
could not be investigated since no heart rate measurements was not obtained.