Tail painting technique as an aid to oestrus detection in cattle.

The value of heat detection by tail painting was assessed by simultaneous visual observation and regular plasma progesterone assay in grazing animals; 88.1 per cent of all heats were accompanied by a positive tail paint record and 30.1 per cent of positive tail paint records occurred in dioestrous animals. Conception rates to the first insemination were 57.6 per cent and 57.9 per cent for heifers and cows, respectively. Of seven animals which showed behavioural oestrus but had intact tail paint, three conceived following insemination. These results suggest that tail paint may be a useful aid in heat detection.