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Extension > Agriculture > Dairy Extension > Milk quality and mastitis > Benchmarking herd SCC

Benchmarking herd SCC

Jeff Reneau
Professor, Dairy Management

October 8, 2011

Is your herd's Somatic Cell Count (SCC) higher than you want? Are you wondering what to do about it? Understanding herd SCC dynamics can help direct your attention to where the trouble is. Is it a herd problem or a few high SCC cows? Is it new infections in fresh cows or lactating cows, or a buildup of chronically infected cows? Benchmarking your herd SCC variables will help. Recent U of MN analysis of the Minnesota DHI herd summaries has resulted in development of a MNDHI SCC Benchmarking Scorecard (Table 1). Using your DHI #302 Herd Summary report for data, place your herd numbers for each variable in the table below to see where you stand compared to other Minnesota DHI herds in 4 different SCC categories.

Table 1. MN DHIA SCC Benchmarking Scorecard.

DHI Herd Summary Variables

SCC Categories (x 1000)

Your Herd

< 200

200-299

300-399

> 400

SCC Average

157

251

353

513

 

% > 200,000

16.4

24.7

32.9

43.4

 

% NIR Lactating1

8

10.4

12.4

14

 

% Chronic Lactating2

8.3

14

20

27.8

 

% NIR Fresh3

11.6

13.5

15.1

15

 

% Chronic Fresh4

6.2

11.1

17.7

26.5

 

RHA Milk lbs

23,186

22,275

20,610

18,906

 

RHA Fat lbs

865

831

780

728

 

RHA Protein lbs

706

681

636

589

 

1 NIR Lactating = new infection rate in lactating cows that on a previous test day were less than 200,000 SCC and are now greater than 200,000.
2 Chronic Lactating = lactating cows with 2 or more consecutive monthly test days greater than 200,000 SCC.
3 NIR Fresh = new infection rate in cows that calve with SCC greater than 200,000 on the first DHI test day.
4 Chronic Fresh = cows that on their last DHI test of a previous lactation were above 200,000 SCC and also on their first test day after calving were greater than 200,000.

 

Now using the DHI #370 SCC Flex report or the DHI #421 Test Day Bulk Tank report identify which cows are the culprits contributing the most SCCs to your herd SCC. By using these reports, you can quickly characterize your herd SCC problem.

Clinical mastitis is annoying and can be a serious herd problem. However, greater than 70% of a herd's SCC will usually come from sub-clinically asymptomatic infected cows (cows with SCC greater than 200,000). One of the greatest assets of monthly individual cow DHISCC testing is being able to accurately characterize the SCC dynamic in your herd. Figure 1 is a diagram of herd SCC dynamics. The level of your herd's SCC will depend on the number and duration of infections and the rate of new infections. High or increasing levels of new infections in both lactating cows and fresh cows signals immediate problems in dry or lactating cow management. On the other hand, in some high SCC herds the problem is the result of a buildup of chronically infected cows. Whether the problem in your herd is characterized by new infections in fresh cows and/or lactating cows, or is a buildup of chronically infected cows, each will require different problem solving solutions to achieve success in lowering and maintaining a lower herd SCC.

Drs Bey (left) and Farnsworth

Figure 1. Diagram of herd SCC dynamics.

Figure 2 is a modification of a flow chart developed by Quality Milk Production Services at Cornell University but using MNDHI data. Using your herd SCC benchmarking results and identifying those individual cows contributing most to the problem, you can use this flow chart to help develop an effective action plan. For example, if only a few cows (<5%) are contributing to your BTSCC problem, this is not a herd problem but an individual cow problem. Follow the flow diagram and suggested action list to narrow your options in dealing with these problem cows. If you have more than 5% of cows contributing to the problem, you should consider this a herd problem and will need to explore more deeply into the herd SCC dynamics. The flow chart below provides suggestions to narrow your investigation in the discovery of causes as well as suggesting some of the appropriate SCC lowering actions.

Your herd SCC records are critical to helping you, your veterinarian and your other dairy consultants in conquering your high SCC problem.

Drs Bey (left) and Farnsworth

Figure 2. Flow diagram for high BTSCC problem solving.

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