Guidelines on the Disease during the Conversion Period

• To create and maintain recording and monitoring systems;
• To find out what is causing mastitis on your farm;
• To achieve acceptable mastitis levels by the end of the conversion period, particularly to minimise the presence of contagious mastitis in the herd; and
• To learn to dry off cows without blanket antibiotic dry cow therapy.

• The vet should be told about the standard requirements.
• It is a good idea to ask the vet to help with the monitoring and assessing of the mastitis situation during the conversion period.

• The farm should set up a mastitis treatment recording system.

• The standards require that all treatments for disease should be recorded, including those involving no drugs.
• The mastitis records should include the following: name/number of the cow, affected quarter/quarters, dates, duration, frequency and type of treatment, length of the withdrawal period (both statutory and organic) and outcome of the treatment (e.g. success/failure/lost quarter/cull/removal to suckling etc.).

• The farm should start sampling milk from mastitic cows for bacteriological examination.

• For a good targeting of mastitis control measures, it is important to know what is causing mastitis in a herd.
• The best starting point is to contact the vet for advice on where to have the bacteriological examinations done (see Practical Advice at the end of this chapter).

• If the farm is not a member of a milk recording scheme, they should consider starting monthly milk recording that includes SCC measurements, and learn to use the Californian Mastitis Test (CMT). (See Practical Advice at the end of this chapter).

• It is important to keep an eye on the somatic cell counts throughout the lactation to be able to identify subclinically infected cows.
• Decision-making about drying off and culling should be based on SCC recordings and bacteriological examination.
• CMT will help the herdsman to monitor the situation in between recordings and to identify infected quarters. It is also helpful in determining when to include milk in the bulk tank after a case of clinical mastitis.

• A system to analyse mastitis records (both treatments and SCC) every six months should be set up to find out what the mastitis levels on the farm are like.

• It is a good idea to get the vet involved in this.
• It is a good idea to calculate simple mastitis indicators for the herd (see Practical Advice at the end of this chapter).

• Once the first analysis of the mastitis situation has been carried out (within the first year of conversion), a mastitis control or reduction policy should be formulated.

• It is a good idea to get the vet involved in this.
• The mastitis parameters and the information on causative bacteria should be considered, and the causes for high levels or spread of contagious mastitis should be identified.
• If a reduction of mastitis levels is considered necessary on financial/animal welfare/milk quality grounds, a written mastitis control/reduction strategy should be planned and written targets should be set within the second year of conversion.
• It is important to consider each farm on an individual basis and to design mastitis control strategies and set targets that take into consideration the unique features of each farm, rather than expecting all farms to achieve a common standard.

• If the farmer is interested in alternative methods of mastitis treatment and prevention:

• All the available alternatives should be considered carefully (see Treatment);
• The need to learn the methods correctly should be emphasised
• The treatment outcomes should be recorded carefully to provide useful information on the use and efficacy of the new method; and
• Milk should be withdrawn from the bulk tank for an adequate period even when no statutory withdrawal period exists.

• If the farmer wants to carry on using antibiotics as the main treatment strategy in clinical mastitis cases, the following should be pointed out:

• Once organically certified milk is sold from the farm, milk from the treated cows should be withdrawn from the bulk tank for twice the statutory period or for 7 days if antibiotic preparation used ex-label.
• The milk from the treated cows should not be given to the calves until the statutory withdrawal period is over.
• If an animal is treated more than twice in a year with antibiotics, it loses its organic status and has to undergo a new conversion period to regain it.
• To use antibiotics in a prudent way, the farmer has to record all treatments, including quantities and batch numbers of the drugs used. The choice of an antibiotic should be based on a sound understanding of mastitis epidemiology in the herd (i.e. routine bacteriological examination of all mastitic cows).

• The use of antibiotic dry cow therapy (DCT) should be phased out gradually during the conversion period.

• Initially, cows that would benefit from DCT should be identified, based on lactation period, SCC recordings, mastitis incidence and bacteriology during the previous lactation and cow characteristics (bag size, teat condition, age of the cow, earlier mastitis history etc.).
• Special precautions should be taken to ensure that no antimicrobial residues are left in milk when it is included into bulk milk after calving (use of cow-side test recommended).

• Dry cow management should be improved during the conversion period to insure minimum mastitis risk for dry cows.

• Improvement of dry cow management, particularly during the first two weeks of the dry period when the cows are vulnerable, is important (i.e. clean and dry housing conditions with daily bedding, avoid putting recently dried off cows on contaminated paddocks etc.).
• The cows should be dried individually, considering their yield and mastitis/SCC history.
• Abrupt drying off has been shown to be more effective, but requires the ability to separate the dried off animal from the sight and sound of the milking herd, on a limited diet.
• Teat sealants and teat plugs at drying off should be considered to prevent infection in the first two weeks (reapply daily if needed). During the summer months, tar should routinely be used to repel flies.
• The farms should aim at stopping routine (all cows treated) antibiotic DCT 12 months before the first organic milk production date. If the herdsman still feels it necessary to treat some selected cows after this point, he should contact his certifying body for further advice and permission.

Practical advice on:

• The local veterinarian might be able to carry out the bacteriological work. If not, she or he will be able to advise you on the nearest commercial laboratory or VI centre that will do it.
• Often, the cheapest way to get bacteriological examinations done on milk samples is to freeze the samples over a period of time and send a number of them to a laboratory at the same time (be sure to agree with the laboratory that they will accept frozen samples beforehand). A good time to start sampling is at the beginning of the calving season.
• Some commercial laboratories offer considerable savings when multiple samples are submitted; e.g. £16.50 for the first sample and £3.00 for each additional sample.
• Taking good milk samples for bacteriology requires skilled practice and great care. Advice should be sought, preferably from the farm’s own vet.

• If the farm is going to collaborate with their veterinary practice in mastitis control, they should ask the practice about the preferred mastitis-recording format. The best form of record keeping in the parlour is on individual cow cards that are easily accessible and show a cow’s whole disease and event history at one glance, but a day-book or a desk top diary is just as good, as long as everybody involved in milking keeps good records.
• Every recording of a case of mastitis should include the following information: date, cow number/name, quarter, treatment (duration and frequency included), and length of milk withdrawal and outcome (success/failure/other outcome).
• To get the most out of the records, they should be summarised and analysed every six months or more often. The farm’s veterinarian is capable of doing this if data is submitted to him regularly.

• The best practice is to get the farm’s veterinarian to do this once or twice a year from summarised farm records.
• The key mastitis parameters are:

Number of cases/100 cows (no. of cases recorded divided by no. of milking cows multiplied by 100): if this figure is above 35 cases/100 cows or if it is higher than during the previous observation period, the farm should take action to improve the situation;

Proportion of the herd affected (no. of cows with at least one case of mastitis in the observation period divided by no. of milking cows): if this figure is high, you are probably dealing with an environmental mastitis problem; the estimated national average is around 25%; and

Recurrence rate (no. of quarters that have had one or more cases of mastitis in the observation period divided by no. of all affected quarters multiplied by 100): if this figure is high, your treatments are probably not very effective and/or you are dealing with chronic infections that are difficult to cure; the national estimate is around 18%.

• This is a kit that will help the milker evaluate somatic cell counts in milk from different udder quarters immediately.
• It is particularly useful on organically managed farms where mastitis remedies that have no statutory withdrawal periods are used. It will help the herdsman to decide when to put the milk back into the bulk tank, in order to avoid high bulk tank somatic cell counts and putting mastitic milk into the supply chain of organic milk.
• It will also help the herdsman to recognise affected quarters when the obvious symptoms are mild or he can only see a "clot in the filter".
• It is easy and quick to use, reliable and relatively cheap for what it does.
• The reagent must not be allowed to freeze and needs to be warmed up in hot water if it is very cold.
• You can get a starter kit from most veterinary practices or dairy suppliers.