Udder Health: focus on dry period outcomes
The dry period isn't just the end of lactation - it's the start of the next productive cycle and her future depends on it being a success.
The dry cows are often called the forgotten cows - they can slip down the priority list when the focus is on the day to day jobs with the milkers. But it would be a missed opportunity not to consider the dry period outcomes that are most relevant to your herd and monitor these outcomes over time.
What counts as a dry period success for you on your farm? A cured cell count? A healthy calf with good colostrum uptake? A quick transition into the highs? No complications with milk fever or ketosis? A low cell count at first recording? Low levels of mastitis in that first month of lactation? Clean, fertile cows a month into lactation?
Most of you are recording a lot of information either through your milk recording, on farm software or via your own spreadsheets, Bray boards or whiteboards - and this data becomes really valuable when it is reviewed, protocols are tweaked and outcomes are monitored.
There are a few dry period outcomes we can review very simply to give us some big win opportunities for udder health - especially for those who are either starting out with selective dry cow therapy (SDCT) or who have made changes to their dry cow protocols recently.
DRY PERIOD CURE RATES:
This looks at what happens to your high cell count cows as they are treated through a dry period. The dry period is probably the only chance of cure for a high cell count cow so it is crucial to know if your treatment choice is working, that your criteria for treatment at dry off is set correctly and to have a plan for any that fail to cure.
Target dry period cure rates: > 85% of high cell count cows curing over a dry period.
CASE STUDY:
This farm had 100% dry period cures in the 5 months leading up to May 2019 but a change in drying off protocols and treatment choice at that time made cure rates drop well below the target of 85% - follow the red line on the graph which tracks cure rates over time. This is a low cell count herd with low levels of clinical mastitis - but the ongoing risk of poor cure rates over the dry period means high cell count cows remain infected and that infection pressure builds up over time in the milking herd.
Criteria for dry cow treatments from July 2020 have now been altered, treatment choice has changed and outcomes will be monitored regularly to make sure things get back on track.
Johne's testing - does stage of lactation affect the result?
All dairy farmers now need to be signed up to one of the 6 Johne's control strategies as per the National Johne's Management Plan. For most herds, this usually involves antibody testing the adult herd quarterly with their milk recording or testing strategically at least twice a year to coincide the results with breeding decisions and calving management.
Johne's antibody levels are always low initially then increase over time as the disease progresses but there can be a couple of years when levels rise and fall before they stay consistently high.
Does stage of lactation affect the milk antibody test?
The stage of lactation can affect antibody levels. When a cow calves there is a flooding of antibodies from blood into milk to make colostrum, so at calving blood antibody levels drop and milk antibody levels can rise.
At the end of lactation the milk volume tends to drop off so there are the same "number" of antibodies in a lower volume of milk, and so we can see a rise in number of infected cows identified on milk testing in late lactation.
Is this a problem?
Johne's management is always limited by not knowing every infected individual - so identifying more potentially infected cows and managing those cows differently at breeding and calving to protect the next crop of calves is always going to be the right thing to do.
Making sure your Johne's control plan is achievable every day of the year is one of the biggest challenges we face in making headway with Johne's. Sitting down as a team to problem solve and share ideas, innovations and new testing opportunities can really help protect the next generation of heifers.
Next Month - can we quantify the Johne's risk of feeding whole milk to calves?
Bovine TB: vaccines and the future
Some of you will have heard the recent news that cattle TB vaccine trials have been given the go ahead - here's a few more details for you, but if you want any more information on TB click on the link to TB Hub below.
Is there a potential TB vaccine for cattle? Yes "CattleBCG".
How well does the CattleBCG work? In the APHA experimental challenge model CattleBCG produces a range of protection: a third of cows are fully protected, a third are partially protected (fewer lesions, less spreading) and a third have no protection - this is similar to the outcomes of the human TB vaccine.
Why can't we use the vaccine now? BCG vaccine affects the skin TB test which is the cornerstone of our bovine TB eradication policy - it would increase the number of cows reacting to the bovine injection and becoming false positives. The World Organisation for Animal Health (OIE) advises cattle must not be vaccinated for TB if the skin test is to be used as a control method.
Are there any tests that can tell between vaccinated and infected cattle? Yes. APHA have developed a DIVA skin test as the most likely candidate to use alongside CattleBCG - if this is approved it will be able to tell if a cow is infected or vaccinated and will only pick up those who are truly infected.
When will we be able to use CattleBCG and the DIVA skin test? Both the vaccine and the test need Veterinary Medicines Directorate (VMD) approval and field trials have been given the green light to get underway this month. Phase 1 will be the DIVA skin test trials which will start in TB free herds in the Low Risk Area and should be completed by Dec 2021 when a decision will be made to continue onto Phase 2 or not. Phase 2 will assess the vaccine and DIVA test in vaccinated herds in the High Risk Areas. All field trials should be completed by 2024 with a timeline of 2025 to roll out the vaccine and DIVA test if all goes to plan.
Bovine TB will never be fixed by a vaccine alone - we will still require strict ongoing biosecurity for both cattle and wildlife but there is an opportunity with vaccine to reduce infection pressure on farm and for it to be part of the toolkit for TB eradication in the future.
Meds News
BoviPhos
Milk fever can be complicated by low phosphorous - these cows don't recover from the usual IV calcium treatment and seem weak on their back legs and they often can't quite get up.
The injectable form of phosphorous Foston is now off the market; Vigophos is an alternative which goes IV or we have BoviPhos in stock which is an oral phosphorous drench. BoviPhos provides 45g of phosphorous which is absorbed quickly and can be used in milk fever cases that aren't responding like you would expect.
Hypophysin
Hypophysin is a longer acting version of natural oxytocin which increases muscle contractions in the uterus after calving. The uterus needs to contract back down quickly after calving to get rid of any contamination as well as helping to expel the placenta, and these contractions can be weaker if you've had to assist at calving, if she had a large calf or twins, or if there are any ongoing milk fever issues.
The receptors Hypophysin attach to in the uterus are short lived so 3-5ml should be injected ASAP after calving for full effect.
HFV Team
Building a team who share the ethos, commitment and vision of what we do at HFV has been a top priority for me over the past few months and I am delighted to officially welcome Tom Jackson to Haywood Farm Vets this month. Tom will be a familiar face to many of you; he brings a wealth of experience, a really keen eye for detail and a few Spaniel passengers!
Tom Jackson
BVSc MRCVS
"Hello, I'm Tom - many of you will remember me from previous years, having worked with Paula between 2014-2017.
Over the past few years I have been working with a wide variety of production systems, from block-calving grazing herds to high-yielding intensive units and everything in between. One of my key interests is dairy cow fertility and I will be studying towards the Diploma in Bovine Reproduction over the next two years.
I'm excited to be teaming up with Paula again as part of HFV, and look forward to working alongside you all in the future. Coffee, milk, no sugar thanks! See you all soon, Tom."
INFO
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