The weighting for the somatic cell count (SCC) trait has been an interesting discussion point. There is a common, misunderstood, perception that SCC can be an issue particular to OAD milking. Unfortunately, this opinion frequently comes from TAD farmers who have negative experiences brought about from putting their herd onto OAD late in a dry season (when there appears to be few other options); this can result in a bulk count doubling and running into the grading zone.
The majority of the OAD farmers admit they must be vigilant with mastitis, treating and culling appropriately. However, if best practice is observed, bulk counts are kept under good control. A statistic that supports this, and really blows me away, is that the average SCC for OAD farmers (supplying milk to Fonterra) is actually lower than TAD counterparts across the season.