Dry Cow Antibiotic Therapy
This document provides guidance for veterinarians authorising dry cow therapy in relation to the Statement on Authorisation of Dry Cow Therapy.
Education is critical to the success of plans to reduce antimicrobial use (AMU). Veterinarians, farmers and the industry need to understand the “why” in order to accept the “how”.
Importantly blanket (whole herd) antibiotic dry cow therapy (BDCT) use is not “banned” and this document outlines in what circumstances BDCT treatment could reasonably be used. The aim of this dairy-industry-wide strategy is to move away from uninformed prophylactic use.
Our overarching goals in relation to AMU are:
- Optimising dairy cattle udder health while limiting livestock associated antimicrobial medicine use.
- Ensuring sustainable efficacy of our antibiotics and protecting public health.
The availability and use of antimicrobial medicines has transformed the practice of human and animal medicine. Infections that were once lethal are now treatable, and the use of antimicrobial drugs has advanced global health as well as animal health, which is a key component of policies to improve animal welfare, food security and food safety.
Preserving the efficacy of these life-saving medications, as well as their availability for both human and veterinary use, is therefore essential to preserve our future. The development of antimicrobial resistance (AMR) compromises this dual objective and impacts our ability to successfully treat infectious diseases.
Veterinarians have the privilege of being solely responsible for the availability of antibiotics on farm. This social license is contingent on maintaining the availability and efficacy of antibiotics for human use into the future.
Increased AMR levels would adversely affect animal health and welfare, as well as dairy farm profitability and sustainability, and is of public health concern. Selective Dry Cow Antibiotic Therapy (SDCT) has an important role in reducing AMU in the dairy industry because reductions in AMU are expected to decrease (or at least stabilise) AMR associated with production systems (McCubbin et al.: Invited Review: Dry Cow Therapy).
The majority of recent clinical trials concluded that SDCT can be implemented in commercial dairy herds without negative consequences for udder health (McCubbin et al.: Invited Review: Dry Cow Therapy).
Stewardship of a medicine means ensuring its use is justified and appropriate. The explanatory notes to Section 1 of the Veterinary Medicines section of the Code of Professional Conduct set out that:
- Justified use means that a valid reason exists to use the veterinary medicine based on accepted medical principles. Veterinarians are expected to make conscientious and judicious use of current best evidence and integrate this with their own clinical expertise and experience when making decisions about the treatment of their patients.
- Appropriate use means the product and the way it is administered are suitable for the situation.
This means that veterinarians may be obliged, and have the autonomy, to say no to some requests for BDCT from farmers.
Commentary on the Statement on Authorisation of Dry Cow Therapy
Whole Herd Antibiotic Dry Cow Therapy
The Statement says that "Veterinarians should only authorise whole herd DCAT to manage animal welfare in herds with indicators of a particularly high prevalence and/or a justifiable risk of infection..."
The word ‘should’ is used to provide advice and recommendations to veterinarians to maintain, or aspire to, high standards of professional conduct. "Should",in this context, is to provide direction to veterinarians that a reasonable number of animals and herds under their care receive SDCT authorisations.
Whether something is "reasonable" can be considered by asking:
- Does it meet the current agreed standards of the profession?
- What would other veterinarians think and do in the same situation?
The objective here is that the overall number of antibiotic dry cow therapy (DCAT) treatments is being actively reduced.
Practically, this may mean for an individual veterinarian, or for a group of veterinarians in a clinic, that they are critically assessing each herd and are making reasonable efforts to increase uptake of alternative treatment approaches (i.e. selective teat sealing treatments) so that the proportion of herds under their care receiving BDCT is actively reducing.
Table 1 of the Statement, quotes SmartSAMM Technote 14 in setting out five indicators of a high herd prevalence of infected cows at dry off and high incidence of new infections over the dry period and states: "for herds to be considered eligible for whole herd antibiotic DCT, it is recommended that all five criteria are met, or three criteria if no individual cow SCC data is available."
This provides an evidence based medicine framework that supports intervention using antimicrobials where it is proven to be appropriate.
Comprehensive udder health improvement plan
The Statement says: "Where a veterinarian authorises whole herd DCAT, they must also ensure a comprehensive udder health improvement plan is implemented."
This means that, where veterinarians for whatever reason find themselves authorising BDCT, they they must also be putting in place an active process to encourage the reduction of the use of these RVMs.
In the traditional sense, where for example the herd meets the Technote 14 criteria, a comprehensive udder health improvement plan should include the usual metrics.
However where the herd does not meet the Technote 14 criteria and yet the veterinarian reasonably decides to authorise a BDCT program a comprehensive, udder health improvement plan is not necessarily a mastitis investigation but should include appropriate steps to address the issues faced by that particular farm or farmer.
If a farm moves to SDCT from BDCT, where mastitis management has been heavily reliant on DCAT, and with no other forms of control or changes in management, the potential for failure and a subsequent negative experience is likely to be high.
This may, for example, expand to include educational processes to enhance a farmer’s understandings and beliefs about the risks associated with AMR, and animal welfare aspects of dry cow treatment programs as well as the ‘why’ such as the wider implications in relation to trade and market access.
Where the decision not to move to SDCT relates to mitigating circumstances such as the capacity of the veterinarian, or the veterinarian’s business, to deliver alternative dry cow treatments programs e.g. where there is insufficient human resource or skills within the business, we would expect there to be plans and efforts to implement the necessary changes to achieve a transition away from BDCT over a reasonable period of time.
This could relate to recruitment activities or the development of education programs and extension tools for veterinarians and farmers to address acceptance of the principles and benefits of better antibiotic stewardship. This may include knowledge and understanding about trade and market access, AMR, and animal welfare.
For stewardship programs to be increasingly successful they will benefit from including social science related aspects that address the social, psychological, and behavioural factors that intersect with decisions around antibiotic use (e.g. cultural differences, incentivisation programs and economic benefits (for both parties), beliefs about animal welfare, pride, authoriser’s and user’s age or other demographics, and a fear of losing clients to vets "down the road who may be less discerning and may say yes to a request for BDCT" i.e. those prepared to continue to authorise BDCT).
Some factors affecting authorising decisions
The following extract (abbreviated) from Antimicrobial Resistance and the Social Sciences: A Narrative Review (available at nccid.ca) relating to AMR and Antibiotic Use – Cultural Factors sheds some light on the way some medicines are “socially transacted throughout the therapeutic process”:
The transactional, relational underpinnings of antibiotic prescribing have also been described in a study conducted in communities along the Mexico-United States border. A relationship has been demonstrated (in human studies) between greater public health knowledge (i.e. on “safe” antibiotic use) and lower rates of antibiotic purchasing. However, the cultural context used between patients and pharmacists generally had a stronger economic, transactional focus rather than a medical one, reflecting beliefs shared by pharmacists and clients on the patients’ right to purchase medications over the counter without the need for information on medical compliance or medical efficacy.
Furthermore, the authors suggest that there is a significant healing power ascribed to antibiotic medicines, and potential individual-level harms are often minimized or ignored in these interactions (28).Another relevant cultural factor addressed in the research literature is the concept of scientific relativity, or the idea that scientific information is re-evaluated by individuals and applied or disregarded based on the individual’s beliefs or opinions.
The program will also benefit from exploration into how contextual factors and interpersonal team dynamics must be understood when developing interventions aimed at mitigating AMR. The leadership and development of these tools would seem suited to clinic groups and representative bodies involvement.
Veterinary authorising behaviours
McCubbin et all reported that antimicrobial prescribing behaviour of livestock veterinarians is dependent on multiple factors, including obligations to ease animal suffering, financial dependency on clients, risk avoidance, advisory skill limitations, producer economic limitations, lack of producer compliance, public health safety, and beliefs regarding degree of veterinary antimicrobial use (AMU) contributions to AMR.
Veterinarians consider economic drivers to be strongly correlated with producer compliance with veterinary recommendations.
Higgins et al. reported most UK veterinarians interviewed preferred SDCT as it aligned with prudent AMU strategies. Regarding veterinary SDCT perspectives, three themes were identified:
- Prioritizing prudent AMU and attempting to maintain producer engagement
- Veterinary experience and ability to influence producer decisions
- Veterinary perceptions about SDCT risks and implementation difficulties, which varied greatly.
With increasing experience in the field, veterinarians were less likely to consider veterinary contributions to AMR as a concern, whereas junior veterinarians were less likely to take a primary prescribing role or make suggestions contradicting senior colleagues, despite an expressed desire to assume more prescribing responsibility.
As senior veterinarians have greater influence on producer AMU, they should facilitate the transition from BDCT to SDCT, where prudent to implement, and increase producer trust of their junior colleagues to further optimize AMU decision. Furthermore, initiatives to mitigate negative veterinary perceptions of SDCT risks and improve producer perceptions of the veterinary community as a “united front” of SDCT support will likely promote industry changes.
VCNZ has a pathway for veterinarians to raise concerns with them in relation to conduct or competence. This process provides an opportunity for veterinarians who are, for example, faced with authorising behaviours by colleagues that appear to undermine good clinical practice to bring it VCNZ’s attention.
For example, in a situation where an initial veterinarian has, using sound judgement, advised against BDCT and the client subsequently obtains BDCT from a neighbouring practice’s veterinarian, the initial veterinarian can notify VCNZ of their concerns.
NZ Food Safety Authority (NZFSA) Audits
This year an AMR Systems Audit team will be conducting nationwide audits of farmers and veterinarians in order to monitor antimicrobial use in animals. These will include reviews of DCAT authorisations.
Below is some guidance for a number of common scenarios that veterinarians may encounter when authorising dry cow treatments. Each scenario should be considered in light of the principles outlined above.
A farm that does not herd test and is not willing to pay for a whole herd RMT test, or does it themselves and we therefore need to trust the results.
Authorising BDCT in this situation is not prohibited by the Statement however it would not meet the principles outlined above nor would it meet an evidence based medicine approach to dry cow treatment.
Veterinarians are not obliged to … provide a requested treatment, providing animal welfare and professional standards are met.
Veterinarians should carefully consider a request for BDCT before deciding whether it is reasonable to authorise BDCT in this situation.
They should also consider the following:
Veterinarians should use their judgement when deciding to accept information they are going to use to rely on for authorising purposes.
It is possible that cost as an ongoing barrier to appropriate stewardship may indicate other important factors impacting the operation of this farm, or it may be an excuse. The former may benefit from further work up, the latter is inappropriate.
Dry cow treatments are generally not considered an urgent situation and benefit from proper planning by both the farmer and the veterinarian. Veterinarians should describe their expectations regarding minimum information and indications of costs well in advance so farmers have sufficient time to budget their finances.
While cost may be a legitimate factor in authorising decisions in some instances, it should be part of a wider strategy for that particular client that is expected to result in meaningful change in DCAT use within a reasonable period of time.
Farmers, Supply Companies and Industry Good bodies also have a role to play in managing AMU and veterinarians can assist with this through education and the advice they provide.
A farm that has done 3 years of selective treatment but the BMSCC has crept up and they want to “reset the clock” using BDCAT to achieve the milk quality premiums offered by the dairy processor.
Veterinarians should use their judgement to apply DCAT where they believe it to be appropriate which may include a situation of increasing BMSCC results.
It would be important for the veterinarian to consider whether this was appropriate in terms of the:
- possible causes
- is the increase material or significant?
- have some infected cows missed SDCT in the previous season?
- have bacteria survived the SDCT i.e. is resistance already building in the herd?
- has there been a failure/breakdown of on-farm udder health controls
- have infected animals been purchased or imported into the herd
- is this an accumulation of chronic infections
- is this an infection with unusual pathogen
- information available (herd testing, bulk milk antibiogram, milk cultures etc),
- solutions (staffing, milking system hygiene systems, age of the herd and culling decisions etc)
- Risk assessment – could BDCT potentially increase the risk of AMR given resistance in the herd is a real possibility if BMSCC is increasing?
- farmer’s drivers, and
- reasonable alternatives
It is also useful to note that in continuing to perform indiscriminate BDCT means that veterinarians are increasing the selection pressure on the commensal bacteria and exacerbating the risk of AMR.
Microbiological culture of milk samples in combination with SCC herd testing would be a an important consideration if it is not in place as it provides the strongest evidence that a cow is infected in late lactation.
Also agreeing to SDCT plan for higher risk individual animals may be appropriate – e.g. cows in their 4th or more season, using teat sealants in the heifers/R1s, and using combination therapy in R2s & R3s.
A variation of the above where they want to lower the SCC threshold from 150,000 so more cows are treated with DCAT and less with teat sealants to achieve milk quality premiums
It appears this is not a BDCT situation and the veterinarians opportunity for judgement applies. The same considerations outlined in Scenario B would apply - can the veterinarian reasonably justify the authorisation of DCAT?
A herd that has always been “BDCAT”, doesn’t meet the Technote 14 criteria but is open to doing some selective treatments this season
This appears to be a positive situation of moving away from BDCT.
It may be an opportunity to safely introduce a combination approach – selective teat sealant application for a low risk proportion of the herd, combination DCAT and teat sealant application and/or only DCAT in the balance.
Farmers that moved to using teat sealants, had dead cows and mastitis as a result and “Will never use teat sealant again”
There is going to be a small proportion of the farmers that veterinarians authorise end of season treatments for that, for one reason or another, the uptake of alternative therapies is a difficult decision.
New approaches may be useful to improve the uptake of alternative approaches and some examples include addressing the competence of farmers administering the products; an understanding of the safety and efficacy of RVM products being used; the animal welfare beliefs of farmers; and, at times, the consequences of incentivisation by processors such as BMSCC incentives.
It may be appropriate for veterinarians to consider addressing issues that relate to better stewardship of RVMs and in particular DCAT in advance of the authorisation process. This may be part of an annual discussion covering the terms of service of the veterinary practice and may act to better outline the importance of managing the use of antibiotics and prepare both the veterinarians and farmers about what is intended.
In this example there appears to be legitimate concerns about the safety of the product used. If the cause has been identified as a hygiene related administration issue and can be addressed it may lend itself to a program of trialling combination or solely teat sealant application in a selected proportion of the herd.
If the cause remains undetermined, which could suggest that there may be an ongoing risk with this particular herd, the veterinarian should perform further investigations to attempt to determine the cause and may be justified in continuing to use a BDCT program.
The rebuilding of the trust and confidence of a farmer over time is important.
Farms that cannot be relied upon to deliver teat sealant in a hygienic enough manner to avoid major complications (training or otherwise) but refuse assistance. We have a responsibility for managing animal welfare risks too
Refer to Scenario E.
In this example the farmer has the primary responsibility for the welfare of their animals. Veterinarians have a responsibility for helping animal owners manage the welfare of their animals.
This situation seems to fit with competence concerns of the farmer and animal welfare risks. Cases such as this may benefit from exploring the barriers for these farmers – e.g. is it a cost related issue? Is it a pride related issue? Is it a skills related issue? etc
While veterinarians have a responsibility for assisting with the management of animal welfare, they are not obliged to continue to deliver RVMs where farmers refuse to engage in appropriate levels of care based on cost alone.
NB: Good stewardship is more than just selling product.
Low BMSCC herds that use BDCT as part of their strategy to stay low and don’t want to move away from this. If BDCT is prescribed then a milking management visit will have limited value. The real issue is education around AMR
Refer to Scenario E.
This is another situation where authorising BDCT is not prohibited by the Statement however it would not meet the principles outlined above nor would it meet an evidence based medicine approach to dry cow treatment.
Veterinarians should carefully consider this before deciding whether it is reasonable to authorise BDCT in this situation.
In this example veterinarians should consider the underlying drivers of the decisions of the antibiotic users (farmers). For example it may be more than just the farmer thinking it’s their right to choose to treat all animals with DCAT – which would be inappropriate and unacceptable.
This desire may be related to other factors such as pride, incentivisation, ease of use, cost, animal welfare, misunderstanding or complacency about the risks of AMR etc.
There appears to be an opportunity across the veterinary profession to better understand the belief systems of farmers. Developing an understanding of the social science aspects of farmers and businesses is an important component of veterinarians' role as stewards of antimicrobials.
Sale and purchase agreements with BDCAT specified in the contract
Veterinarians have the discretion to decide not to authorise BDCT in this situation.
This area is complex and DCV and VCNZ have done some work with Stock and Station Agents in this area to try to include clauses that are more applicable to the expected standards.
There may be an opportunity for veterinarians to encourage purchasers and sellers to consider revising a S&P agreement. Refer to Appendix 1 for example clauses.
Note: The clause (developed in conjunction with DCV and VCNZ) in the appendix could be redrafted by veterinary clinics and circulated to all farmers in advance of each season as standard advice to be included in any future S&P agreements.
Older high producing, low SCC cows, that are higher risk for mastitis with teat seal alone?
Veterinarians should consider if these animals pose a risk to AMR.
Microbiological culture of milk samples would be a useful addition if it is not in place as it provides the strongest evidence that a cow is infected in late lactation. For example this would be a useful process to identify S. aureus carriers and to actively manage these out of the herd.
If they are negative on culture and are low SCC cows it would appear that there is no need for DCAT.
Given some of the risks associated with this group relates directly to their high production improved drying off practices will be critical to better manage this issue.
Veterinarians do have the discretion to use their judgment when authorising RVMs. Where they may reasonably consider animals to be of higher risk of contracting an bacterial infection that is likely to be detrimental to an animal’s welfare they may be justified in authorising an RVM. For other farms with similar animals it may be unnecessary due to other factors that relate to better hygiene practices, transition management, farmer competence, farm infrastructure etc.
If a milking management visit is required what is the standard and who is auditing this?
While there are no current audits of milking management visits there is an opportunity for the profession to work on establishing an accepted standard of good practice. VCNZ would welcome this as it in itself would establish a metric that could be used to establish what is considered ‘reasonable’.
This may be an opportunity for DCV to work with VCNZ to develop good practice guidance for DCT programs.
Dairy NZ has useful resources available here .
If the prevailing standard across the profession does not meet the accepted or agreed standard it will be expected to improve.
(Note that the AMR Surveillance and Monitoring team will be conducting audits in 2023).
The statement says, “Veterinarians must be able to justify each individual animal’s treatment plan. This means ensuring there is sufficient clinical evidence to support a need for DCAT use for each animal for which the product is authorised i.e. full herd test results, or validated diagnostic culture, screening culture, or PCR herd testing systems This is hard where no herd testing has been done or where technical resources are stretched. Is there any interpretive commentary on this?
This statement substantiates to farmers that veterinarians do require herd testing or similar individual cow data to continue to provide DCAT. Concurrently VCNZ recognises that there are going to be circumstances that mean that it may be impractical for this to occur this year. Such situations may include:
- Shortages of staff (veterinarians and veterinary technicians) that have the competence to perform the procedures safely.
- Shortages of competent farm staff
- Farmers that have had negative experiences such as mastitis or lost stock after the use of teat sealants.
However, in the long term a farmer’s refusal to have herd testing, or a similar screening process performed will not be a sufficient justification for authorising BDCT.
With farm staffing a challenge and vet clinic staffing a challenge how does VCNZ view the risk of welfare related issues to cows receiving ITS alone without adequate supervision/training? Or put another way if we can't guarantee good welfare outcomes for the cow due to staffing issues is the VCNZ happy for a vet to prescribe whole herd.
VCNZ recognizes the current resourcing issues and encourages veterinarians to use their judgement in each situation. It also encourages veterinarians and DCV to develop strategies to better manage these issues in the coming years.
What is our first responsibility, welfare or antibiotic risk?
VCNZ doesn’t see this as an either/or situation. Both aspects need to be considered and importantly veterinarians responsibility is to be good stewards for the use of antibiotics. Our aim should be to treat infected quarters with antibiotics to improve the welfare of cows and to help farmers manage the risks around teat sealant use through appropriate training to ensure adequate teat disinfection prior to administration. Any adverse risks should be managed and should not drive our authorising behaviours.
How does one move away from whole herd dry cow, where all 5 measures of infection control is working, and hope it won’t go backward?
Most farms maintain a low BMSCC and low mastitis rates through good mastitis management and use selective dry cow as part of the process. This is achievable on all farms and the opportunity for vets is to assist farms to reach this goal as they move away from whole herd. This may involve a milking time visit, culling plans, mastitis diagnostics, staff training etc. We also remind veterinarians to consider the relevant section of the Code:
Consider whether any other evidence-based treatment or management option might be an alternative or adjunctive treatment to antibiotic therapy or might be used to increase the chances of a successful outcome (such as antisepsis, wound drainage, and vaccination).
The Statement describes a comprehensive udder health improvement plan needs to be implemented where BDCT is authorised. What does this involve?
VCNZ has used this terminology to allow veterinarians to use their judgement to decide what level of oversight is needed for each farm.
There are various ways a veterinarian may gather sufficient information during their “Drying Off Consultations” with farmers in order to authorise dry cow treatments.
Some of the commonly recognised methods include:
- A "Milk Quality Consultation" (sometime known as a "Dry cow Consult") should be conducted for all of their clients where the basic mastitis epidemiological information is collated (e.g. bulk milk cell count, herd test, drug use, current management strategies) in order to make informed drying off decisions. While there may be variation amongst practices about how sophisticated this process is, this is seen as a baseline and is required to authorise DCAT and teat sealants.
- A Mastitis Control Plan - as part of a broader milk quality consultation, recommendations can be made around improvements in mastitis management, such as improving teat spray practices, milking machine maintenance etc.
- A Milking Management Visit which involves attendance at milking and includes assessment of teat skin, teat ends, teat spray coverage plus assessment of the milking machine and environment, et cetera and leads to recommendations for change.
- A Mastitis Risk Assessment visit with a milking time visit that includes dynamic measurements of milking machine function throughout the milking ; Assessing the cow mastitis risk including teat condition, teat end damage, milk–out and cup slip; herd factors, and staff interactions with the cows and milking techniques that may increase the mastitis risk.
- A consultation with the farmer about their goals and concerns. For example this may be more about ensuring the farmer’s processes are appropriate and then working with the farmers to build their trust and confidence as selective DCT programs are introduced.
While the particular method a veterinarian employs to determine their approach to mastitis may not be listed here we expect them to use their judgement to decide what information and level of oversight is needed for each farm system.
One of the key considerations is that the Code expects veterinarians to apply their judgement in each unique circumstance or farm.
That authorising DCAT RVMs for herds should be specific to each individual situation or farm based on the information the veterinarian has for that farm.
It may be appropriate, for example, for SOME herds with older high producing, low SCC cows, that are higher risk for mastitis with teat seal alone to receive DCAT yet in other herds it may be unnecessary It might not be considered appropriate for a veterinarian or clinic to have a policy that all older high producing, low SCC cows, that are higher risk for mastitis with teat seal alone receive DCAT no matter the farm’s circumstances.
Some farms using wintering practices may be at high risk for environmental mastitis, e.g. there may be difficulty keeping product in the teat canals due to trucking after dry-off. Veterinarians would be expected to consider this factor and steps that may be taken to mitigate this issue for each farming system before authorising BDCT.
Hypothetical continuous improvement scenario
A veterinarian has 2/3rd of their herds using SDCT programs.
They are aware that the objective is to use as little BDCT product as possible and preferably none.
Achieving 2/3rd of a practice’s herds using SDCT programs is currently considered to be in the upper quartile for the profession.
This veterinarian, understanding the objectives, wants to continue to reduce their BDCT authorisations but faces human resource constraints given the global shortage of veterinarians and veterinary technicians.
As a result of this they elect to transition 10% of their remaining herds away from BDCT each year until they are able to rebuild their team’s capacity.
They also plan to develop with their neighbouring practices and through DCV better staff training resources and client facing extensions tools to approach the issues the industry is facing with a special focus on social science factors.
Veterinarians have a role in stewardship of antibiotic use on farm.
Currently this privilege and responsibility is at the behest of society and it is important that the expected level of stewardship is met by the profession.
The evidence supports the concept of the justified and appropriate use of antibiotics and the examples outlined here provide guidance to veterinarians.
The Statement: Authorisation of Dry Cow Therapy and this guidance should be seen as a signal to veterinarians that the expectations regarding these authorisations will be more closely scrutinised in the future.
AMR – Antimicrobial resistance
AMU – Antimicrobial use
BDCT – Bulk Antibiotic Dry Cow Therapy
BMSCC – Bulk Milk Somatic Cell Count
DCAT – Antibiotic Dry Cow Therapy
DCV – Society of Dairy Cattel Veterinarians
SCC – Somatic Cell Count
SDCT – Selective dry cow therapy
VCNZ – Veterinary Council of New Zealand
Dry Cow Therapy (DCT) clause
All cattle must be dried off following a recognised (Dairy NZ) dry cow management strategy. At the Vendor's expense and in consultation with the vendor's veterinarians, unless stated otherwise in Clause 13, the following will apply:
All lactating cattle will receive teat sealant authorised by the vendors veterinarian and administration is to be supervised by a registered veterinarian.
2. Individual cow SCC
Individual cattle will also receive an appropriate Antibiotic DCT authorised by the vendors veterinarian where the animal’s :
- Individual/ or Ave herd test SCC is >150,000/ or ^………. cells/mL
- had clinical mastitis in the current season
3. Individual cow SCC and Milk cultures
Individual cow SCC and milk cultures are performed on every cow as an indicator of infection status and to decide on cows suitable for purchase.
4. At risk herds
In consultation with the purchasers and vendors veterinarians, all lactating cattle will receive an appropriate Antibiotic DCT where there are significant risk factors. This DCT will be authorised by the vendors veterinarian: Where the veterinarians do not agree that the cows need to have Dry Cow the purchasers Veterinarians decision will be binding.
Risk factors may include:
- a high proportion, or prevalence, of infected cows at dry off (refer to Dairy NZ SmartSAMM Guideline 14 and Tech Note 14 criteria)
- the risk for new infections is high (e.g. long transport distances, or farm system at destination).