“Dirty” is a term used to describe cows that have endometritis, an internal infection of the uterus, which most commonly develops following calving.
Endometritis generally affects 10-20% of a herd (average 17%) and leads to poorer reproductive outcomes, including reduced submission rates (take longer to cycle), reduced conception (higher number of empties) and six week in-calf rates. The bacteria, pus and inflammation associated with the infection impacts overall cow health and welfare and, by negatively impacting on the next season’s mating, will also cost you financially.
Endometritis can occur in any cow but some are at greater risk (hence the term “at-risk”!) than others. The at-risk group includes those that have had an assisted calving/twins/retained foetal membranes, calved prematurely and/or aborted, were induced/sick/down, or are skinny (less than condition score three). Needless to say (but SO critical that I’m going to say it anyway!) identification of these cows therefore requires excellent record keeping!
However, unfortunately the at-risk group are not the end of the story as up to two thirds of cows with endometritis may be outside of this group. Metrichecking (using a metricheck device to detect pus within the vagina) is a convenient and efficient system used to detect infected cows in a herd.
The timing of metrichecking is crucial – three to four weeks following calving is optimal. If done too early (less than two weeks after calving) we may treat infections which are on the way to self-resolving. If done too late (greater than four weeks after calving) the cervix closes and pus may not be detected in the vagina despite infection being present in the uterus. Consequently cows need to be metrichecked in “batches”. A straightforward approach to easily identify each batch is to tail paint all cows post-calving with a particular paint colour – one colour for the first four weeks of the calving period, then a different colour the next four weeks and so on.
Ideally this approach to metrichecking would be applied to the whole herd but, if this is not a viable option for you, there are alternate approaches that can be employed. Once cows with endometritis have been identified an antibiotic is infused through the cervix to treat the infection. Ideally treated cows are rechecked three weeks later to ensure treatment has been successful.
So, consider the effect “dirty” cows might have on your herd and discuss the pros and cons of potential management plans with your vet to work out the most suitable approach for you.