The correct recommended programme is to metricheck the cows in batches when they are 8 – 21 days past calving. For convenience or cost saving, you may have tried doing the whole herd just once in October. Anecdotally, it has been noticed that less cows come back dirty with this system. It would appear, that by waiting, a number of cows will self-cure, so less metricuring is needed.
A study on 15,000 cows in the North Island investigated this idea. They split the cows into two groups:
It was found that when dirty cows were rechecked at the following metricheck, there was no difference in the proportion of dirty cows between those that were treated and those that were left to self-cure.
So, on the face of it, it seems that metrichecking and treating early is often unnecessary because the cows will cure themselves. However, when the two groups of dirty cows were followed through to mating, those cows that were treated immediately had significantly better reproductive statistics.
Treated cows had a 9.6% higher 6-week in-calf rate (WIC rate) and a 3.25% lower 84-day not-in-calf rate. On a whole herd basis, this translated to a 2.4% higher 6-WIC rate, a 1.65% lower 84-day empty rate, and the cows that were treated every 21 days conceived 2 days earlier. What appeared to be dirty cows self-curing may largely just have been the metricheck devices` lack of accuracy in finding dirty cows after more than 21 days post-partum.
Checking cows in batches every 8 – 21 days post calving will give the best balance between giving cows a chance to self-cure and ensuring that dirty cows are not missed.
