Variation is key to cell count levels.
Many producers believe they can cull or treat their way to cell counts below 400,000 cells/ml. While that might work in the short term, it’s not a long-term solution, says Jeff Reneau, a University of Minnesota veterinarian and milk quality specialist.
“Culling a few cows is OK,” he says. “But changing habits is not so easy. People on the brink of 400,000 are going to be in trouble until they make management changes.”
If bulk-tank cell counts drop to between 350,000 and 400,000 cells/ml, there’s an 80% to 90% chance that they will exceed 400,000 at least once in the next 30 days if variation between milk pickups exceeds 25,000 cells/ml. That’s according to an analysis of three years of 1,500 bulk-tank somatic cell count (SCC) records done by Reneau and his graduate students.
Herds that consistently exceed 300,000 cells/ml have a 50% or higher probability of exceeding 400,000 at least once each month. To lower that probability to below 25%, bulk-tank SCCs should be below 200,000 cells/ml, and variation between pickups no more than 75,000.
“We have enough information to get all of our herds under 200,000 cells/ml,” Reneau says. “The problem is with compliance and implementation of recommendations.”
Herd size makes a difference, of course. Herds with fewer than 100 cows are more affected by one or two high cell counts in the bulk tank. Yet even in larger herds, day-to-day variation is 41,000 cells/ml at an average count of 400,000. If the herd’s average is 100,000, day-to-day variation will be just 15,000.
Inconsistent milking procedures, teat dipping and stall management are as much a plague on large dairies as they are in smaller herds, Reneau says. By calculating your day-to-day variation, you can determine if it’s your consistency or the process itself that is the problem.
“If a farm has a higher than desired bulk tank SCC but day-to-day variation is low, compliance and consistency is good,” Reneau says.
Walk around the dairy to see what’s causing the high average. It’s often sanitation: cow prep procedures, bedding management, even nutrition deficiencies that result in immune response dysfunction.
“If, on the other hand, both bulk tank SCC and day-to-day variation are high, you need to be more consistent in applying procedures and think about improving processes,” Reneau says.
Do milkers get every teat end clean? Is each teat dry before unit attachment? Is there at least 90 seconds of lag time before attaching units for every cow? Is every teat of every cow postdipped completely? Is feed available after cows are milked to ensure teat end closure? Is every stall cleaned and groomed after each milking?
Achieving low SCCs is not a matter of luck or the weather, Reneau concludes. It’s about consistency and control.
- April 2012