Drying Off
Drying off cows on a seasonal dairying farm often comes with a sigh of relief. After a long season, all staff are looking forward to a well earned break. The cows too seem to relish the change of pace where they don’t have to trudge to the shed night and morning. One thing’s for sure, they get really grumpy when you try to get them back to the shed a week later!
There are some special things happening at drying off. The udder begins to involute (shut down) and many protective and restorative mechanisms kick in which will ultimately prime it for a successful start to the next lactation. This includes the formation of a keratin plug in the teat end in most cases.
In the rush to get the cows out of the shed for the final time, stop for a minute and think about the process, because it is a critical point in lactation and one that can set you up for success or failure in the coming months. There are a few seemingly small things that can have a big impact.
Drying off date.
If you farm in a system where feed may run short and cows are on the thin side, don’t leave drying off too late. Keep a close eye on thinner cows, particularly if they are young. You must dry them off in time to gain the required condition before calving, and if you leave it too late you will run out of days to gain the required weight to calve in ideal body condition. Condition scoring the whole herd two months before the normal drying off date will give you time to act if needed.
Remember that drying off is a 10-14 day period where the cows will not gain weight – in fact, they might lose it – and factor this in as you consider drying off date relative to condition score targets.
Alternatively, if body condition and feed supply are not a problem you might like to maximise lactation length and shorten the dry period. Be careful you don’t run in to milk withholding issues with your antibiotic dry cow therapy choice. Long acting products can catch you out and trigger residue violations. Careful planning, eg treatment selection according to confirmed calving dates, can neatly sidestep the issue.
Drying off Nutrition and Management.
The best way to dry cows off is “abrupt cessation”, ie rapidly changing from the current frequency (this may be twice a day) to not at all. Temporary Once a Day milking or skip-a-day practices are not good for mastitis control.
For cows doing less than 5L per day this is not a problem – just do it.
Between 5 and 10L per day, cows will handle drying off fine provided nutritional and management changes are implemented immediately after the last milking.
If cows are making in excess of 10L milk per day it can be a challenge shutting that production down and nutritional changes must be made at least a week before the last milking. This usually involves reducing feed intake substantially, and this should be done fairly steadily, rather than suddenly.
Abrupt cessation does not mean all cows have to be dried off on the same day – it can be staggered to make the workload manageable. This is particularly important if a number of treatments and procedures are being done at the time. Staggering could be as simple as doing the last two rows/spins each milking until the herd is done.
After drying off, send the cows to a clean paddock, to minimise the teat end challenge while milk may be dripping. Keep feed levels down to maintenance for 7-14 days, at which point they may be brought back into the shed for a post dry off checkup.
Drying Off Treatments
The dry period presents an unparalleled opportunity to clear up udder infections. Antibiotic Dry Cow Therapy (DCT) has a long udder contact time, which pushes cure rates sky high. Make sure cows get DCT if they have had any clinical cases during the year or any evidence of infection on herd test results (above about 150,000 ISCC on any herd test). These antibiotic treatments must be prescribed by a vet who has knowledge of your herd.
The use of Intramammary Teat Sealants (ITS) is often highly beneficial as well. These plug the teats immediately, whereas the natural teat plug can take some weeks to establish. There is good evidence that for high risk cows that using both DCT and ITS is well worthwhile. Alternatively, ITS can be used in low ISCC cows as a simple preventative of calving mastitis.
Drying off may also be the last time for a month or two that you get a chance to treat for parasites, vaccinate, supplement with trace elements or perhaps even ear tag. If doing these procedures, make sure you are well organised; not only to achieve a good job but minimise time on concrete for the cows waiting in line.
For further advice on treatments, drying of nutrition or management don’t hesitate to contact the clinic.
Mastitis Diagnosis
Properly detecting mastitis is a very important part of both control and treatment. Infected cows pose a risk to other cows in the herd, as their infection can be spread (sometimes very quickly) to other cows via the milking machines and udder handling by staff.
Infected cows left untreated produce less and less milk, and if the infection gets into the deeper tissues there is long term damage to the udder. Not only this, but the infection gets progressively harder to treat. If the cow develops a chronic (long term) infection, her somatic cell count may rise, increasing the risk of culling and decreasing her value for sale.
Most mastitis is moderate. There is some clotting or discolouration of the milk, but the rest of the body is unaffected. All mastitis enters via teat, and can only be passed between quarters via the milking machine or the hands of the assistant.
Lumps appear in the milk due to pH change, tissue debris and inflammatory fluid. The milk may become watery, bloody and even smelly. The changes can range from severe to mild but is considered clinical if visible or subclinical if invisible but smouldering away. Further milk tests may be required to clarify infection status. These may be the likes of a Rapid Mastitis Test (RMT) which breaks up the DNA of bacterial and pus cells and makes it clot, giving a thick gel when the infection is present.
Mastitis can be found at any stage of lactation, including the dry period(!) Swollen quarters or hind leg lameness can be a giveaway. In these cases, only strip the quarter if it is hot and painful, otherwise you may be losing the keratin plug for no good cause.
As most mastitis occurs around calving, good colostrum mob mastitis detection can nip problems in the bud. This mob can become a quarantine mechanism, with only clean cows entering the main milking herd. Stripping daily to examine the milk and a further close examination (possibly including RMT or conductivity) as cows exit the colostrum mob should be done, and affected cows either monitored or treated.
If cows are to be treated, a milk sample can be taken prior and frozen. This can be cultured if necessary down the track for useful information. Strip treated cows just after the end of treatment and again at the end of the drug withholding period.
For the first 6-8 weeks, a weekly strip is advised or strip targeted cows after herd test or whenever the filter sock gets clots. If things are going well after that, milking staff remaining vigilant for swollen or sore quarters may be all you need.
What is Mastitis?
The root words contributing to the term mastitis are mast (udder/breast) and itis (inflammation). Some people think of the udder as a bag of milk and mastitis a problem when the milk goes bad, but that is only part of the story.
The udder is in fact a very fleshy tissue, and while it has tiny milk producing pockets (alveoli) and milk ducts the vast majority of it is cells and blood vessels. Therefore when the udder gets inflamed we have an inflamed tissue, or an inflamed organ (which, believe it or not, is classified as a skin gland by those in the know).
Being a skin gland, the only way infection can reach the udder is from the outside. The teat end is designed to keep bacteria and other nasties (such as yeasts, eg thrush) on the outside. It has a tight circular ring (sphincter) and sticky layers of keratin to stop would be intruders in their tracks. Infection only occurs when the teat canal is open/damaged and there is significant challenge (numbers of bacteria) on the outside.
Infection progresses
Infection may come from the environment, particularly mud and dung. A common environmental bacteria (Streptococcus uberis) is often the culprit in environmental infections. A faecal organism (E.coli) can result in a type of mastitis which makes the cow sick or even kills her.
If infection takes hold it moves up the teat canal and into the milk tissue. From there it may multiply rapidly on the surface of the milk tissue or invade the tissues, forming small abscesses which become very difficult to treat. Bacteria can also end up in the lymph nodes (glands) and the cow can be sore or lame.
Occasionally the bacteria or the toxins they produce will reach the bloodstream, making the cow very sick, or even killing her. Emergency intensive care is required to get the cow back on her feet.
Cure or Cull?
Some mastitis infections clear up without treatment, but we have no way of knowing which ones those will be. The best way to economically maximise cure rate is to treat visible (clinical) mastitis with antibiotics immediately. The best opportunity to cure a cow is the first time you see mastitis. The second and third time around it gets progressively harder to cure, so make sure you give a decent treatment first up!
If infections are ongoing, they either show up as repeat clinical cases or subclinical mastitis. While subclinical mastitis is not visible to the naked eye there are significant numbers of somatic cells (pus cells) pouring out with the milk. These cows can be very difficult to cure, and options include either giving an extended course of treatment, waiting until the end of the season, or even considering culling the cow. It is best to discuss these individual cows with us, and we can give you solid advice about these big decisions.
Milk Quality Consultations
Nowadays there is a legal requirement for veterinary consultation before any prescription drugs can be administered to animals. This is why we have a formal sit down before prescribing Dry Cow Therapy (DCT) for any herd. However, good mastitis management is not just about DCT, and we have found the annual consultation is not just a good time to prescribe, but it is a chance to set up a very successful total control package.
Good mastitis control requires data. There is no way to assess progress without accurate and timely information. This comes from sources including Milk Processor bulk cell counts, Herd Tests, Treatment records and drug sales. All of this data can now be recorded and processed electronically, making detailed analyses available at the click of a mouse. The Mastitis Focus Report, MINDA and Infovet are all good examples of this.
A good mastitis control plan will always have elements of continuous improvement. In fact it involves cycles of measuring, choosing, doing and reviewing – and the improvement follows.
It looks something like this:
The annual mastitis consultation (often called Annual Mastitis Review) is the key structured meeting in this process. A second meeting is often staff training on farm, which is part of the implementation. If you want to have an Annual Mastitis Review we will need to get data organised in advance. This could involve getting your treatment records summarised, or getting reports from your herd improvement company. There might be an easier option such as Infovet where one software package does all the work for us. Regardless of the method, we need good data to save time and make more informed and valuable decisions during the consultation.
An Annual Mastitis Review presents a really good opportunity for you to make progress (Gain) and keep ahead of the game (Maintain) in mastitis control. We also find it very professionally rewarding to accurately measure your status and your progress. Don’t settle for anything less than a decent Annual Mastitis review this drying off!
Udder Health
Mastitis is the main internal udder condition we deal with. Other udder conditions are essentially “external” and skin related. Listing the conditions in approximate order of importance:
Trauma
The milk vein supplying the udder is huge, and roughly 200L of blood circulates through the udder per minute. Therefore any haemorrhage from the vein can lead to rapid blood loss. This is a true emergency. Lie the cow down, get pressure on the vein and call the vet immediately.
Quite often the teats can be cut, either from the cow standing on them as she gets up or perhaps as she jumps a wire. This too is a relative emergency. If not stitched within 12 hours prospects of saving the teat are slim. A vet will quickly assess the likelihood of recovery based on the type and extent of the damage.
Long term teat end damage
Milking machines place unnatural stresses on cow’s teats, and over time they can develop “RSI” of the teat ends. Normal teat ends are soft and smooth, with a very small orifice. Long term changes induced by milking include roughened teat ends, small haemorrhages, the opening of the teat orifice and firmness/swelling. There is a scale of assessment for damage and regular monitoring is advised, particularly if problems have been observed. Solutions include equipment change, milking technique change or adjustments in pulsation and vacuum.
Short term teat damage
Traumatic milking processes, where there are gross stresses on the teat can result in short term discolouration (red or blue) of the whole teat. Large haemorrhages may appear at the teat end. Swelling may appear at the teat base and the orifice can be extremely open (up to 2mm wide)
Teat and Udder Skin conditions
Like any sensitive skin, the teats and udder can be affected by excessive environmental dampness or dryness, abrasions or cuts, sunburn, frostbite and chemical damage. Cows are also prone to photosensitisation from plant allergies or facial eczema, which affects light coloured teats. There also infections such as herpes virus which can make a real mess of teat skin in the short term.
Staph bacteria normally live on the skin of the teat and even within the teat canal. However, with long term teat end damage these normally harmless bacteria can take a hold of teat ends and cause nasty lesions. Things can get even worse if bacteria become involved and the teat end can become an ulcerating mess.
There are some very good pictures available as online and hardcopy resources we can access. We recommend you contact us if you have any concerns or questions, or maybe next time when out on farm we take a closer look at udder and teat health on your farm.
Mastitis Prevention
In the mastitis world, it is fair to say that “an ounce of prevention is worth a pound of cure”. While treatment is often very effective at clearing up mastitis, the infection is often some days old before it is infected and the cow has already taken a hit in health and production.
Preventing mastitis is not only much better for the cow; farm staff involved in treating and managing the case are put under much less pressure and have the opportunity to do much more productive and pleasurable things with their time if a case is prevented in the first place.
Naturally, there are many “would be” and pretender products and practices that claim to prevent mastitis. Talk is cheap, but science (while costly) is trustworthy. As veterinarians, we are committed to evidence based medicine when advising you on mastitis prevention.
There are some proven prevention practices which have great research evidence and have been proving themselves in recent times. We have long experience with all of these.
Proven Strategies
Every mastitis problem is solvable and preventable.
It is just a matter of methodically working through all the possible causes and developing a step by step continuous improvement process on your farm. Prevention is a huge cornerstone in this process, and we have great advice to offer in that regard.
Somatic Cell Count
Soma means body. Somatic cells are body cells, which do not belong in the milk..... at least not too many of them.
Milk is formed by a specialised skin gland – the udder. As milk is filtered from the rich blood supply deep in the udder tissue there are a small number of skin like cells that naturally come adrift during the process. These number about 20-30,000 cells per ml in the finest quality milk. As a cow ages and during late lactation the udder sheds more of these cells, and as milk volumes drop during late lactation these become more concentrated per ml and might creep up towards 100,000.
Above these levels, any rise in somatic cell count is abnormal and is a very accurate indicator of infection. When infection strikes the udder responds like any other part of the skin/body by sending in a defending “army” of white blood cells.
During an episode of mastitis, there is in fact a war raging. On one side we have the bacteria, on the other side we have the defending army of the immune system. The battle is intense, as the defending army releases all sorts of “smart bombs” to kill off the enemy. Most of the cells from both armies die in the process and on a microscopic level there is a BIG mess. The dead soldiers and all the weapons of war congeal and make the clots we see as clinical mastitis.
During a case of clinical mastitis, the somatic cell count can rise to 10 million cells or more per ml within 2 days. Above this level the milk becomes too thick to measure. At times there is major damage to the udder tissue and blood leaks out as well, further elevating the somatic cell count.
The infection may take a few days to cure, but the somatic cell count will take weeks to settle down. It is often 3 weeks before it drops below the 400,000 cells/ml mark. The cleanup process after the battle takes a long time.
On an individual cow basis a somatic cell count below 100,000 is considered normal, and above 150,000 is considered infected somewhere in the udder. Above 500,000 is serious. This number is a composite average of the four independent quarters of a cow, so there will be overs and unders contributing to the average. The count is usually only made at Herd Testing, where a representative milk sample is siphoned off at milking time and analysed in a laboratory to give an Individual Somatic Cell Count (ISCC). If wanting to compare quarters within a cow, quarter samples can be taken and analysed in the laboratory, but alternatively, there are simple cowside tests that give indicative results.
Cowside tests measure components of the milk which change during infection. If strictly measuring the somatic cell counts, the detergent base of the Rapid Mastitis Test (RMT) is used to lyse (break up) somatic cell DNA, which then clots like mucous. Milk from each quarter is squirted in to a special “paddle” and mixed with RMT reagent. A positive thickening indicates quarter Somatic Cell Counts (SCC) in excess of 500,000. A similar mechanism is used within the milkline to detect high cell count for the whole cow during milking (Cellsense).
Other cowside tests generally measure the sodium content in the milk. This rises as blood products leak in to the milk and therefore the electrical conductivity of the milk rises. This is measured with a simple voltmeter in either a hand held electrical device or an inline reader. Some sophisticated milking machines measure a combination of falling yield and rising conductivity to pinpoint potentially infected cows during milking.
On a herd basis the average or “bulk” somatic cell count (BMSCC) can be measured in samples of vat milk. These are routinely taken on a daily basis as the milk is collected, and analysed within 24 hours of pickup. All cows in the herd contribute to the result. Given that infected cows crank out large numbers of cells, quite a small proportion of the herd (5-10%) with high ISCC can have a significant effect, ie one bad apple can spoil the whole bunch.
A good level for a BMSCC is below 100,000. Many milk factories pay premiums for milk below 150,000 and all penalise at higher levels (350,000-400,000). Milk consistently above 400,000 will eventually be refused by the processor as it fails to reach international standards. High BMSCC milk is more costly for the factory to process, as it contains inflammatory products which hinder some production processes, such as cheese culture. The shelf life of high SCC milk is shorter than normal.
Down on the farm the BMSCC is an important indicator of the udder health of the herd. As a rule of thumb, approximately 10% of the herd are infected with mastitis for every 100,000 BMSCC, for example at 200,000 there are approximately 20% of the herd infected. An infected herd produces less milk, with an extra 2% available for every halving of BMSCC below 400,000. Many farmers set goals to maintain an average BMSCC below 100,000 to optimise milk production and significantly reduce the risk of high BMSCC penalties.
BMSCC trends and patterns both from daily milk production and Herd Test information (possibly 4 times a year, but can be analysed to cow level) can assist mastitis diagnosis, management and control on farm. Farmers are notified by the Dairy Company if milk is substandard, and data is available online to look at daily and seasonal patterns. It is easy to set goals for BMSCC and monitor them.
Dairy Company average BMSCC is of interest at a national level, and hundreds of millions of dollars could be made by improving it. Programs such as Countdown Downunder and SmartSAMM have a national industry approved BMSCC goals. At farm level the potential gains are usually in the tens of thousands, and industry approved economic calculators are available to work out the potential for each farm. If you would like us to estimate the cost of mastitis on your farm, please contact the clinic for a no obligation estimate calculation.
Treating Mastitis
Effective treatment of mastitis is more of a science than an art, and lots of good information is available to assist treatment decisions. The well proven scientific principles around clinical mastitis treatment include:
Milk Withholding
Keeping antibiotic out of the vat is a critical part of treatment these days. Dairy Companies and end user consumers have very high standards and heavy penalties for infringements. All products should be well labelled with the mandatory withholding period.
The “missus T” (MRST acronynm) is an excellent risk management summary to avoid the costly and painful milk residue violations. Remember also that calf meat withholding periods apply if the cow is treated prior to calving or a calf sucks antibiotic milk.
Mark all cows (Dry cow treated and lactating cows),
Record them temporarily and permanently,
Separate the treated mob from the milkers and
Treat thoroughly with a legitimate proven treatment
High Cell Count cows
Cows developing long term infections require special treatment. If late in lactation the most cost effective option is to treat with Dry Cow Therapy, drying the cow off early if necessary. Earlier on in the lactation and if the cow has a low cell count history, lactating therapy may be worthwhile. Cowside tests including RMT and culture are advisable and the cow’s history should be taken into account.
Dry Cow Therapy
The single most effective treatment of mastitis is Dry Cow Therapy (DCT). Antibiotics get exposed for udder bacteria, giving stunningly good cure rates, ie in the 90s for streps and the 70s for staphs. Plan your DCT well in advance and make sure it caters for the different needs of your herd.
If you are finding any aspect of mastitis difficult make sure you contact the team at the clinic. Mastitis might be getting you down, but you can conquer it!
Tirau Veterinary Centre has been an integral part of our local community for over 40 years. Our customers know by experience that they can rely on us for sound advice and treatment options and that their animals are in the very best hands with our team.
