Metrichecking is done to diagnose endometritis, the infection of the lining of the uterus post-calving. Affected cows appear clinically healthy and can even be cycling but will be unable to conceive until the infection has resolved.
Risk factors for the development of endometritis include twin calvings, assisted calvings, retained foetal membranes and other deficiencies and health problems around calving. However, even cows that have had a very uneventful start to the season may have endometritis and require treatment. Research shows that by just checking ‘at risk cows’ 20% of the affected cows in the herd may be missed and without treatment, they are likely to conceive later or not at all.
In the past, we have checked herds once, late in the season. We thought that animals self-cured given time. Recent research has shown these "self-cures" have reduced chances of getting in-calf. So rather than truly self-curing they become harder to be detected with a metrichecker. For cows where infection lingers for months causing chronic inflammation and damage, there is potential the infection will also be more difficult to cure.
Most herds should have over 60% of their animals calved by week 3, with close to 90% calved at 6 weeks. If we were to only do one check a month out from the start of mating (week 9 of calving), we are jeopardising the reproductive chances of 60-70% of the herd and only checking 20-30% of the herd in the best window to detect and treat them.
We recommend checking cows in batches between 8- 18 days post-calving so we can catch infected cows early and treat them well before the planned start of mating.
Return on investment for whole herd metrichecking breaks even where only 2 % of the herd is infected and there is a 4 to 1 return for checking and treating early, mostly from cows getting in calf earlier.
If your autumn cows are calving now, call us if you have any questions about metrichecking your herd and how this can improve repro results in the upcoming mating season.
Dr Jenetta Fosyth, BVSc - Farm Vet at Te Kauwhata.