Aktivitet som sjukdomsmarkör på kalvar i gruppsystem
Since long, Sweden has had exceptionally low calf mortality compared to most
other countries. The tradition has been to keep calves in individual pens. With
increasing number of cows per herd there is now a larger interest in more efficient
and economical group systems for housing calves. However it has been noticed
that bigger herds have more health problems and higher calf mortality than
smaller herds. The early signs of disease are harder to detect when the animals are
not fed manually. Studies show that the health of the calves influences how
productive and healthy they become as cows. The health of calves has therefore
become more important and there is a need for systems that can help detecting
diseases among calves.
Respiratory diseases are often difficult to detect in calves. In Kvigprojektet (?the
heifer project?) only half of the cases of pneumonia confirmed by veterinarians
had been detected by the farmers. In a group system it is not easy to identify
which one of the calves that suffers from diarrhoea. Diarrhoea among calves is
rarely caused by bacterial infections and should therefore not be treated with
antibiotics but with oral electrolyte therapy. In a pilot study it has been shown that
the number of visits where the calf was not allowed milk in an automatic milk
feeder decreased when the calf had an infection. This is an example of
information from automatic systems that is not used.
The aim of this study was to investigate the possibility of using activity measures
as indicators of disease among calves in group housing systems. Up until now
activity measuring has only been used as an instrument for research. If activity
measuring could be developed to help identify disease among calves in group
systems this could be a valuable help for farmers, in trying to detect calves in an
earlier stage of illness. This in turn could help avoiding unnecessary use of
antibiotics and also increase the growth rate of the calves.
The material used in this study consisted of 113 calves, of which 31 were
considered to be healthy and 82 calves were considered as ill at some point during
the time in the group pens. All calves got a pedometer (Icetag analycer) fastened
to one of their hind legs before entering the pens. The pedometer measured the
activity of the calves in percent per 24 hour period.
The classification of calves as healthy or ill was based on criteria from clinical
examinations performed by veterinarians 3-4 times per week. Of the 82 sick
calves a comparison of sick and healthy periods were made within each calf.
There was a significant difference in activity, where the sick calves had lower
level of activity than healthy calves (t=4,52, p