Fertility in Dairy Herds - Advanced Part 2 : Benefits of treating the individual cow

Copyright ©NADIS 2017 Benefits of treating the individual cow: 'Oestrus not observed' ('ONO', missed heat, 'not seen bulling') The routine veterinary visit is an important part of the management of fertility. A key part of the routine visit is the examination of cows which have not been seen in heat, but have been calved long enough that they are eligible to be inseminated. Some of these cows may have abnormal ovaries (cystic structures or ovaries that are small and inactive) or have an infection of the uterus several weeks after calving (endometritis or 'whites'). However, a large proportion of cows presented as 'not seen bulling' are likely to have apparently normal reproductive tracts and a corpus luteum (CL) on at least one ovary. The presence of a CL indicates that the cow has probably been in heat and ovulated within the last 5-17 days. If cows which have cycled are not treated then they are likely to carry on cycling, coming in heat roughly every 21 days, until they get pregnant. However, it is likely to be at least seven to ten days before they come into heat again, and, as the previous heat behaviour was missed, it is quite probable that subsequent heats will be missed too.