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National mastitis survey: lessons to be learned...

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01 November 2010, at 12:00am

RICHARD GARD reports on some of the findings of the second national mastitis survey

FOR the second year Intervet/Schering-Plough Animal Health has collected information about mastitis from 10% of the 11,256 dairy producers in England and Wales. 

There are some rather surprising findings, which have been examined by Andy Biggs and James Allcock. Impressions gained from work with clients may not reflect the overall trends and there is no doubt that changes have taken place, even from 2009 to 2010. 

All regions of the UK are represented and herd sizes from below 50 cows to over 500. Two-thirds are between 100 and 250 cows. Three-quarters of the herds are Holstein Friesian with Friesian and Channel Island breeds also included.

The majority of the farmers (80%) indicated that their herds had a cell count below 200,000 cells per ml with 9% below 100,000. Only two farmers admitting to a cell count above 350,000 cells per ml.

It is worth considering how these cell count data compare with the situation in practice herds, as cell count is relatively easy to collate. Some of the management aspects of the survey may be more difficult to interpret for lessons learned of value to dairy clients.

Higher milk yields

More than 75% of the farmers indicated that over half of the cases of clinical mastitis occur within the first 100 days of lactation, generally after the first month of lactation, presumably coinciding with peak yield. This may indicate the issue of energy balance related to yield perhaps, but nutritional management was not part of the survey.

However, between the 2009 and the 2010 study, more of the herds recorded higher milk yields, both in terms of yield per cow and gross milk sales. In excess of 150 of the herds reported sales of over 2 million litres in the year up to the summer of 2010.

With some herds already feeding winter rations because of a shortage of grass, an early spring may be an important element for the next annual sales or the margin of sales to feed purchased will be cut.

Approximately 30% of the farmers expect to treat fewer than 20 quarter cases of clinical mastitis per 100 cows per year, with half indicating 20 to 50 quarter cases. It appears that farmers are using combination antibiotic therapy regularly to treat clinical cases (around a third of the dairymen who completed the survey).

Overall, a third of the farmers select Cobactan as their first- line treatment but it is not clear whether this is the same third who indicated that they use combination therapy. The aim would be to promote a compatible injection together with an intramammary and, glancing at the product literature, combination therapy indicates higher concentrations of antibiotic in the infected quarter and therapeutic levels in the blood plasma.

It would be interesting to know whether there is an increasing use of combination therapy for treating clinical mastitis, whether the regime is seen to be successful and if a full course of injectable is used or just an initial booster dose.

Most (80%+) of the farmers use teat sealant in combination with dry cow therapy, roughly half routinely and others some of the time.

More information would be welcomed about the treatment of high cell count cows. Over half of the farmers indicate that they treat these animals but the detail of cow selection, the therapy used and the value perceived is not within the report.

There is information about mastitis in heifers with 16% of the farmers reporting that more than one in 10 heifers suffered mastitis during their first lactation. It would help to know whether these cases are related to difficulties with aspects of milking, issues of not getting in calf or not settling into the milking herd environment.

No bacteriological tests

Bacteriological milk testing does not seem to be high on the list of actions for these farmers. Fewer than 20% had tests carried out on three or more occasions in the year. A third said that they never utilised bacteriological tests.

Of the results that were available, the proportions were Strep. uberis (36%), Staph. aureus (31%) and E. coli (23%). These figures are consistent year on year and over two-thirds of the farmers report difficulties with clinical mastitis treatment. These farmers regularly use four to six intramammary tubes per case with 10% of the farms using up to 10 tubes.

As expected, there is a variety of teat preparation options with around half of the herdsmen not washing teats before milking. Pre-dipping or pre- spraying is applied to about a third of the herds, with medicated wipes and dry wiping being used by a few enthusiasts. Herdsmen are wearing gloves for milking on 70% of the farms. 

Nearly all the farms apply post- milking disinfection in some form with an even split between spraying and dipping. Over half of the farmers say that the cows are foremilked before applying the clusters. Within the survey, automatic cluster flushing is utilised by a few farmers as an alternative to dipping or spraying, whereas a large number of the farmers (44%) indicate that cluster disinfection is carried out.

Contaminated milk transfer

At various meetings, Roger Blowey has surprised audiences by demonstrating that one or two millilitres of contaminated milk can be transferred between cows from the short milk tube.

Various options are available for cluster flushing including a bucket of disinfectant, use of a jug and bucket, manual sprays, air wash and automated dipping and flushing.

Roger has reported on the cluster flush mechanism developed by Vaccar utilising sanitised water and compressed air. The system is fitted to existing milking units and enquiries indicate that over 500 of the systems have been installed in recent years with a similar number of installations from other manufacturers.

One of the claims for cluster flushing is that the farmer has “substantially reduced vets bills”.

The value of this survey is possibly linked to whether what is taking place matches veterinary advisers’ expectations of the management of herds under their care or whether it encourages a more detailed approach to herd management awareness. One of the aspects that Andy

Biggs raised is the waiting time for cows in the collecting yard. The effects on mastitis could be related to standing time. Standing time is recognised as a bad thing in relation to lameness (or reduced mobility), dietary issues and fertility performance among others, as the cows are not eating or lying down. One of the measures could be the yield of the herd in relation to the number of milking units.

Standing time increasing

A common concern is the higher production with management and facilities not keeping pace with performance. As yield increases and the number of milking units remains the same, the milking time and standing time will increase unless positive steps are taken to arrange milking into yield groups. Three-quarters of the farmers indicated that they had monthly milk recording for the herd but the survey does not indicate whether cows are grouped for milking. Are the herds in the survey, with increasing yields, suffering mastitis problems that will need to be addressed not by bigger and better therapy but by milking time management?

An analysis of the national survey is available from the Cobactan folk as a print-out or computer thumbstick. There is a great deal of data here and any suggestions for further points of analysis or additions to the next national survey are being sought (tim.hickman@sp.intervet.com).

It may be possible to have updates to the survey introduced via the web but the option, introduced this year, for the farmers to provide information online rather than by post was only taken up by 42 farmers. However, being able to download details and conclusions from a website may be of interest to both farmers and veterinary surgeons.

There are clearly many points of detail related to the control of mastitis that continually need to be addressed.