It's almost accepted as gospel that a high somatic cell count (SCC) cow in a small herd can throw off the entire bulk tank even if the rest of the herd is doing well. When it comes to large herds, the conventional wisdom is that a few high-count cows can get diluted by their herdmates.
Think again, says Ed Kreykes, a veterinarian consultant in Sanborn, Iowa.
Recently, he and a team of veterinarians and nutritionists evaluated a 1,500-cow Midwest herd that was averaging more than 90 lb. of milk/cow/day and rolling at over 30,000 lb./cow/year. The herd was in expansion mode and hanging on to every cow it could as it filled new barns.
There were several older cows in the herd producing well over 100 lb./cow/day but that also had extremely high cell counts. In fact, two of these cows were each contributing 3% of the herd's total bulk tank SCC.
Culling the top six SCC cows from the herd would mean a loss of 600-plus lb./milk/day. But by doing so, the dairy's quality premium would jump 16¢/cwt. on all milk shipped. Based on the herd's annual milk shipments, the impact could net more than $30,000 annually.
Culling these cows would also save some 60 tons of dry matter feed annually. At today's feed prices, that could add another $8,000 in annual savings—or more.
Even more important, removing these cows from the herd would reduce the chance of spreading their mastitis to uninfected herdmates, Kreykes says.