Dairy Advice

Counting the Cost of Somatic Cells 

The somatic (body) cells that are detected in milk are mainly white blood cells, which appear in response to infection.  A low SCC is an indicator of good udder health; a high SCC is an indicator of mastitis. As SCC rises, milk yield falls: a cow can have no visual signs of mastitis, yet still have a raised SCC, which means she would be producing below her potential. 

DairyNZ has developed some good tools that you can use to determine the economic cost of udder health problems (www.smartsamm.co.nz). 

The graph below shows the value of the milk potential that is being lost by farms that are not meeting a benchmark for SCC of 100,000 this SCC target: for an average farm the potential loss is around $27,000 a year; for a large farm with high SCCs the loss can exceed $100,000.



Lowering the SCC offers the chance to recover some of this potential loss.  If the average farm mentioned above spent $13,500 on reducing their SCC to the 100,000 benchmark, they could see a 2:1 return on their investment. 

The challenge is to identify the best strategies for reducing your herd’s SCC.  Many factors influence how high the SCC is, so knowing where to start can be difficult.  One of the easiest steps to take involves your herd’s nutrition.  Sub-optimal nutrition can undermine the performance of the immune system, reducing udder health. One mineral in particular plays an important role in combatting mastitis: zinc.

Zinc is needed for the formation of the keratin plug that sits in the teat orifice. This plug forms a barrier that stops pathogens entering the udder. The material in the plug is turned over quite quickly – around 40% of it is replaced each day – so it’s important to have a steady supply of dietary zinc so new keratin can be formed.

Small amounts of zinc are taken up by cows grazing pasture, but if this dietary intake isn’t meeting needs, then zinc methionine can be custom blended into stockfeed.  When used with other animal health practices, zinc can be very effective at helping to reduce SCC levels.