626. Udder infections in the ‘dry period’: IV. The relationship between the new infection rate in the early dry period and the daily milk yield at drying-off when lactation was ended by either intermittent or abrupt cessation of milking

Abstract

1. Records were collected from a herd where many cows were producing relatively high daily yields of milk at the time of drying-off. Animals giving 7 lb. of milk or less daily were dried off by intermittent milking, and those giving over 7 lb. daily were dried off by ‘stop’ milking. The data from 113 dry periods were analysed so that a comparison could be made of the new infection rate in the early dry period according to level of production at drying-off.2. The new dry-period infection rate was found to increase with yield at drying-off. This was not due to age differences between the groups of cows.3. The rise in total infection rate with yield was due mainly to an increase in Str. agalactiae infections.4. A high proportion of clinical quarters were detected in the dry period by the cowmen.5. The yield in the lactation following the dry period studied was not related to yield at drying-off.6. New dry-period infections were significantly (P <0·01) more numerous in quarters of cows that had been hand-stripped during lactation compared with quarters of machinestripped cows.