Aktivitet som sjukdomsmarkör på kalvar i gruppsystem

Sammanfattning: 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<0,01). When only comparing healthy and sick periods for calves with diarrhoea, calves were less active during the sick periods (t=3,53, p<0,01). 41 calves had respiratory disease and also here a significant difference in activity was found (t=2,51, p<0,01). 18 calves had diarrhoea and respiratory disease simultaneously, however in these no significant difference could be found (t=1,66, n.s.). The conclusion from this study is that activity level can be used as an indicator of disease in calves in group housing systems. More research is needed to identify and establish activity levels which are applicable in the practical situation to indicate early stages of disease.