Use of milk sampling to support selective dry cow decision making.

Blanket Dry Cow Therapy (BDCT) has been widely practiced in the UK dairy industry (and the world) since the adoption of the NIRD 5 Point Plan in the late 1960’s.  It has been proven to have benefited udder health and the control of mastitis, especially contagious pathogens.  However, pressure is now mounting for the dairy industry to reduce the amount of antibiotics used in milk production.

Selective Dry Cow therapy (SDCT) has therefore gained momentum both in the UK, but also across other parts of the world.  The Netherlands have been a world leader in this area, partly due to regulatory control and the enforced reduction in the use of antibiotics in the dairy herd.  SDCT can be introduced successfully, without any impact on mastitis control and new intramammary infection rates.  However, to do so needs careful management and the availability of good individual cow records.

Decisions are based on individual somatic cell counts, clinical case history, teat condition and levels and type of bacteria present in the herd. Usually cows are selected for teat sealant only if the last 3 cell counts prior to drying off are below 150,000 – 200,000 and the cow is defined as at low risk of mastitis, i.e. has had no clinical mastitis for at least 3 months and preferably none in the lactation.  However, every farm is different due to the complexities of the number and type of mastitis causing bacteria commonly seen on the farm, other risk factors such as suitability of housing, so it important that the advice of the farm’s veterinary surgeon is sought.

However, accurate individual cow udder health information is essential.  This will include all incidences of mastitis (dates – whether treated or not), any treatment given, quarter affected, product used and number of treatments.  Plus, individual monthly Somatic Cell Count (SCC) data.

Some form of sampling method and device is required.  For pedigree registration an ICAR approved sampling device is needed.  However, for commercial herds all that is required is a reliable sampling device, such as the Ambic Milk Sampler AMS/200, that will take a small but representative sample of milk.  For SDCT purposes this will be for the SCC result, but the sample could be used for bacteriology test, milk composition, progesterone testing and for inhibitory substances (antibiotic residue) test.

After the cow has been milked. The sampling bottle is removed, agitated and then a sample poured into a small test bottle that has the cow ID and date of milk sample written on it.  The sampling bottle is then emptied and placed back on to the sampling device ready for the next cow.

The samples collected can then be suitably packed and sent off for analysis.  The results do need to be in a usable format so that each cow’s results over her lactation can be readily monitored.  Discus with your veterinary surgeon how to interpret the results for selecting cows for selective dry cow therapy.