Very often the best way to investigate mastitis/SCC problems is to be present during milking, and this was a regular part of the Teagasc/Dairygold programme.
Investigations during milking often reveal the reasons for problems that will not be revealed by testing the machine, particularly regarding milking and hygiene practices.
If cows are restless in the parlour, it may indicate electrical problems, cows being packed too tightly, a milking machine fault, or poor milking practices.
Teat end damage is a major tell-tale sign that something is wrong.
Taking clusters off under some vacuum is still fairly common in problem herds.
This may be due to faulty shut off valves or poor milking technique.
Clusters should be taken off and put on without any noise of air or vacuum.
Otherwise, there will be teat end damage which will lead to mastitis and high SCC. Teat end damage also results from vacuum being too high, poor pulsation or inadequate fall in milk line (very common in older machines).
Inadequate use of teat disinfectants is quite common, which is often due to faulty sprayers or the wrong type of sprayers.
The proper usage of teat spray is 15 mls per cow sprayed evenly all around.
In a minority of high SCC herds, it is difficult to identify the cause, and a lot of investigation is required. Disinfecting clusters between cows was found to be a major deterrent to spreading mastitis within infected herds.
Alternatively, if there are only a few problem cows, they could be milked last.
In summary, it could be concluded that the main reasons for high SCCs include the following — faulty milking machines, faulty milking technique such as taking cluster off under vacuum, poor hygiene, inadequate teat disinfectant, inadequate SCC records and culling, problems with power supply, and inappropriate antibiotic use in problem herds.
The aim should be to keep SCCs consistently under 200,000 and have very few cases of mastitis.
The SCCs of first lactation animals should be consistently under 80,000.
If the SCCs of first calvers and other young cows are rising, there is certainly something wrong and urgent action should be taken.
If SCCs are averaging over 200,000, it indicates a level of infection in the herd which is likely to give rise to sporadic outbreaks of mastitis.
Diseases such as BVD can depress the immune system and give rise to SCC issues.