Bulk tank somatic cell count (BTSCC) is one of several parameters used by state milk regulatory agencies to insure consumers a safe, wholesome milk supply. For dairy producers, this means BTSCC is one item that must be constantly monitored and managed. Failure to manage BTSCC could result in a potentially serious loss of income for the farm. This loss of income could occur in three different ways:
- Withholding the milk of individual cows from the bulk tank in order to keep the BTSCC below the regulatory limit of 750,000 cells per milliliter of milk.
- Forcing the producer to sell the milk as manufacturing grade milk which significantly lowers its value.
- Significantly lowering the production of individual cows and the entire herd when somatic cell counts are elevated.
Somatic cells are a naturally occurring product of a cow’s immune system. Somatic cells consist primarily of immune system cells, such as leukocytes, that are utilized by the animal to destroy disease causing organisms. All cows in the herd contribute to the BTSCC. However, some cows contribute to a much greater degree than others. Knowing how much individual cows contribute to the BTSCC is a highly effective tool for managing the BTSCC.
One of the most accurate and least expensive methods of monitoring somatic cell counts in individual cows is available through the Dairy Herd Improvement (DHI) somatic cell count (SCC) program. Milk samples can be taken by a DHI field technician or by a dairy producer and shipped to the DHI lab for analysis. The results are usually available to the producer within 2 to 5 days.
Analyzing one set of individual cow milk samples for SCC can give an idea of how much specific cows are currently contributing to the BTSCC. However, this is not an effective method for managing BTSCC. Individual cow SCC is highly variable and can change dramatically over a short period of time, often within hours or days. In addition, one SCC measurement from an individual cow generally will not give an accurate indication of the cause of the elevated SCC. Routine measurement of SCC (monthly or bimonthly on all milking cows in the herd) gives a much more accurate picture of the possible causes of elevated SCC and possible management techniques to lower SCC.
For example, the DHI-202 Herd Summary Page contains profiles of SCC by stage of lactation. These profiles can give a better idea of when SCC are becoming elevated during the lactation. Are cows freshening with elevated SCC or are they occurring at specific times during the lactation? Knowledge of the relationship between SCC and stage of lactation allows the producer to examine the specific management practices used at various times during the lactation cycle to determine if changes are needed.
Another example can be found on the DHI-210 Monthly Report on individual cows. The Monthly Report contains current information from the most recent DHI test day, such as milk weights, fat percent, breedings since the last test day and current SCC. In addition, the Monthly Report also contains milk production and SCC from the nine previous test days. This can help the producer to identify cows with chronically elevated SCC and to determine what type of managment action (antibiotic treatment, culling, drying off, etc.) may be needed on individual cows.
SUMMARY AND APPLICATIONS
The DHI SCC program is one of the most inexpensive and effective methods for monitoring SCC in individual cows. The DHI program also has several additional profiles and summaries which provide dairy producers with a wealth of information for managing BTSCC. Dairy producers who are using the PCDART program can also design their own profiles and reports. This allows them to further pinpoint possible causes and management solutions to elevated BTSCCs. One final note: Monthly DHI SCC usually cost less than dumping the milk from five average cows for one day!