At any time, it is estimated that one cow in four is affected by sub-clinical mastitis (high SCC), and the cost of high-SCC/mastitis in Ireland is estimated to be about €30m per annum.
On average, there are about 40 mastitis cases per 100 cows in Irish dairy herds. Proper use of a good, licensed teat dip/spray, and good hygiene, are priorities, while ensuring the milking machine is in perfect working order. All the rules and practices of good mastitis control should be carefully followed throughout the year. Animal Health Ireland (AHI), Teagasc and co-ops are doing a lot of mastitis control work.
They have established the “Cell Check/Mastitis” programme, and every farmer should follow it. This programme is broadly similar to what has been developed by Teagasc over the years, and is proved to be highly effective when properly carried out.
The objective of this programme is to maintain a national average bulk milk SCC of 200,000, or less, by 2020. The only barrier to achieving this objective will be to get sufficient farmers to participate in the programme. A study by AHI indicates that net farm income on dairy farms can be increased by €10,000 by reducing SCC from 350,000 to less than 200,000. In the last 10 days of May this year, 15 to 20% of herds had SCCs over 300,000.
High SCCs also cause very significant costs at processor level. According to the Teagasc milk quality handbook, a 100-cow dairy herd with average SCC of 400,000 would incur additional mastitis-related costs of €11,700 compared with a similar herd with a 100,000 SCC. Co-ops are paying a bonus for milk with less than 200,000 SCC, and in some areas, almost 60% of dairy farmers are not availing of this bonus for some of the year. However, the supply to one large southern co-op is averaging well under 190,000 this year, due to their excellent mastitis programmes carried out in conjunction with Teagasc for decades.
It is difficult to pinpoint any particular reason for continuing problems with SCC. The biggest problem is that only about 50% of our herds are milk recorded and often very poor use is made of recording reports. 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, often due to unsuitable sprayers. Proper usage of teat spray is 15 mls per cow, and teats 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, and culled when the opportunity arises. In summary, it can be concluded that the main reasons for high SCCs include 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 average over 200,000, it indicates some 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 problems.