Most know that the farm record system is only as helpful as the information in it. Likewise, all the recorded data is only as beneficial as knowing how to interpret it.
A short course at the 2017 National Mastitis Council Regional Meeting in Boise, Idaho, titled, “What do you need to know about tracking milk quality from a DairyComp record system?” addressed these points.
Mark Kirkpatrick, DVM, of Zoetis led the course with a focus on the best techniques to document and interpret data for determining milk quality. The two primary points of monitoring he stressed were somatic cell count (SCC) and mastitis incidents. These are more important than ever as herds increase in size. “Somatic cells have so much information that a lot of times gets discounted, when we can really do something with this data, and it’s worthwhile pursuing on a dairy,” Kirkpatrick said. He highlighted how both SCC and mastitis have a heavy impact on net farm income.
He advised dairy producers to be especially familiar with knowing the specific factors that are having a positive or negative impact on income. Factors with the biggest positive impact on productivity include: 21-day pregnancy rate, energy corrected milk (ECM) shipped, heifer survivability, number of heifers and milk shipped. Kirkpatrick shared a study, which found that SCC was the second biggest negative effect on net income after net herd replacement costs.
“If SCC deserves this much effect on a dairy, we’ve got to know what those numbers are,” Kirkpatrick said. Production is also noticeably impacted. Kirkpatrick referenced a data set, which showed that for every hundred thousand increase of SCC there are 5.5 pounds lost in milk production.
The National Mastitis Council recommends that farms use a 200,000 SCC as a “cutoff” to monitor milk quality. In record systems like DairyComp 305, a linear score is used to measure this. “When you look at somatic cells, these aren’t normally distributed,” Kirkpatrick said, explaining the reasoning for using a linear score. “Every time somatic cell count doubles, that increases log linear by an additional one.” The system translates cell count into a log linear score that can be easily measured, added, subtracted and so forth. DairyComp uses a score of 4 to mark 200,000 SCC, making it an important number to regularly monitor. “If you see that climbing above, then you’re in serious trouble,” Kirkpatrick said. For example, if a herd has a cell count above a 4, it also means cell count is high enough that the average cow most likely has a subclinical mastitis infection.
In the pursuit of milk quality, Kirkpatrick pointed to a list compiled by Dr. John Lee. Four major groups in every dairy herd that should take priority are the transition and fresh pens, all lactating groups and the chronically mastitic population. In knowing these groups, he also highlighted the importance of mastitis detection and cure for all clinically infected animals. “Record even if not treated,” Kirkpatrick said. “You’ve got to document every case of mastitis.”
With this data identified, Kirkpatrick addressed the best places to check them in the DairyComp system. “I always want to look at that bulk tank command, and I want to look at that first test somatic cell count,” he said. “If I wanted to make an appointment and only look at two things every month, that’s where I’d look to see big changes.”
Another help equation is the cows at risk of infection and the rate of infected animals. Both risk and rate should rank pretty close together, Kirkpatrick advised, no further than 3 points apart if possible. Rate consists of two parts – chronic and new infections. New infections are particularly important to tracking SCC activity in the bulk tank. “If you’re at a 12 percent new infection rate, you are actively adding new somatic cells to your bulk tank,” Kirkpatrick said. He refers to a 5 percent rate as being a “gold standard” and 8 percent as an indicator of doing very good. “Anytime you are not in a similar place with chronics as you are with new infection rates, you are adding chronics and they’re overrunning the system.”
Kirkpatrick concluded the course by encouraging producers to collect milk culture data. DairyComp has the capability to keep track of different mastitis pathogens from culture, each represented by a different digit. 
Jaclyn Krymowski was a 2017 Progressive Dairyman editorial intern.
