Dirty Cows

With heads down into calving, milking and calf rearing, time can quickly pass away and before we know it’s time to get ready for mating season. Even though preparing for successful mating starts well before calving, managing dirty cows early can improve reproductive success.

Dirty cows have a condition called endometritis – an infection in the lining of the uterus which becomes inflamed and produces pus. A pus-filled uterus is a poor environment for a developing embryo and consequently affects conception rates.

Who is most at risk?

Understandably, the cows most at risk of developing a uterine infection are those that have, or have had, an assisted calving, retained membranes, stillborn, twin births, rotten calving, down cows, mastitis, metabolic conditions, or calved in a body condition score of 4 or less.

Even so, studies indicate that almost 1 in 5 cows (18%) with no risk factors or health issues are also likely to have an infection. This represents a large proportion of the herd that may be missed!

Why is it important to diagnose endometritis?

Dirty cows often don’t show signs of illness and appear as normal healthy cows. Recent studies also indicate there is a high prevalence of endometritis within NZ dairy herds, with an average 1 in 4 cows (25%) diagnosed as metricheck positive. This does vary greatly across herds, with some only having a handful of metricheck positive cows to other herds having up to 50-65% of the herd affected.

Delaying treatment of cows with endometritis leads to:

• More non-cycling cows

• Reduced 6-week in-calf rate

• Reduced conception rates

• Higher empty rates

• Less days in milk

• Higher culling rates due to poor reproductive performance

Keeping endometritis in check with Metrichecking

Endometritis is detected by inspecting vaginal mucous collected after insertion of a MetricheckTM device. Anywhere from the mere presence of flecks of pus to lots of pus, changes in colour or a foul odour is likely a sign of infection.

Metrichecking has been shown to be a quick, simple and reliable method of detecting endometritis.

Metrichecking the whole herd is preferred, not just ‘at-risk’ cows as this will give a far greater positive benefits on reproductive performance.

Metricheck scores

Photo sourced from Dr S. McDougall (Anexa FVC).

In a NZ study involving >15,000 cows, treating metricheck positive cows earlier resulted in a 9.6% higher 6-week in-calf rate and a 3% higher 12-week in-calf rate, compared to delaying metrichecking until closer to mating (ie. using the traditional approach of treating cows a month prior to mating). When treatment is delayed, the cervix is often closed, thereby preventing pus from escaping the uterus and making it harder to detect dirty cows. Early treated cows were also found to conceive 8 days earlier

Turning a dirty cow into a clean cow

Metricheck positive cows are treated with an infusion of antibiotics directly into the uterus. Unlike other antibiotics, these have a nil milk withhold. Using the scoring system pictured right, any cow with a score of 2 or greater should be treated (ie. mucous with flecks of pus, obvious pus, foul odour).

Treatment leads to excellent cure rates (up to 90%) so a single treatment is usually sufficient to treat the majority of affected cows. At times though, a cow may require further treatment, so it is useful to re-check all previously treated animals again prior to mating.

Research suggests some cows will over time naturally cure themselves. But leaving this to chance is a gamble as a negative metricheck result does not mean she has cured the infection and inflammation may still be present in the uterus.

Treating endometritis early can give a 4:1 ROI (return on investment). Finding, treating, and curing affected animals early will give them the greatest chance of getting back in calf earlier. So don’t wait to treat cows just prior to mating!