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HFV News SEPTEMBER 2023

In this issue…

Held cleansings - a review

Weaning - a seamless transition for your calves?

Johne's disease - don't forget your priority culls

A warm welcome to Katie!

Held cleansings - a review.

Held cleansings or "Retained Fetal Membranes" (RFM) happen on all farms to some degree.

What should happen to the placenta after calving? What causes a placenta to become retained? What treatment should we give? Does it affect her future fertility? How many is too many?

Most cows will "cleanse" and pass the placenta within a couple of hours after calving, but if she hasn't passed them after 12 hours it's then termed "retained fetal membranes" or RFM.

What should happen to the placenta after calving?

The placenta is a complicated organ that grows throughout pregnancy - it is the attachment between the cow and the calf in the uterus and supplies the calf with the nutrients and oxygen to grow as well as removing the waste products from the calf. There are two parts; the caruncle of the uterus on the cows side and the cotyledon of the placenta on the calf side - together these two things form the placentome. At every placentome there are little finger like projections connecting the two sides and allowing oxygen and nutrients to pass through to the calf from the dam.

Although oxygen and nutrients can pass between the calf and mum, their blood does not mix and so the calf has no maternal immunity in it's blood when it is born - this is why colostrum is SO important in that first few hours of life.

During the normal calving process there is a loosening of the connections in the placenta due to hormone changes both from the calf and the cow, and once the calf is born the blood supply from the calf side stops which causes the blood vessels in the connections to collapse and detach. The contractions of the uterus then help to pass out the detached placenta.

This prolapsed uterus shows the placenta attached to the purple caruncles underneath

What causes RFM?

  • Induction with steroid
  • Calving early
  • Abortion
  • Twins
  • Milk fever
  • Assisted calvings
  • Caesarean
  • Vit E / selenium deficiency
  • BVD
  • Immunosuppression

What treatment should we give?

Unfortunately there are very few effective treatment options for a RFM - choices tend to be based on tradition rather than evidence! Once the placenta has failed to detach it then needs to rot away and this takes time.

Studies show pulling the cleansing out has no beneficial effect at all, in fact it increases the risk of metritis, adds 5 days to her restarting bulling activity, 20 days to her conceiving again and decreases conception rates by up to 12%! The cow only has a finite number of carnucles on her side; if we pull at a cleansing that is still firmly attached the caruncle can become damaged and she needs a minimum number to be able to hold in calf in the future.

There is no evidence that putting antibiotics directly into the uterus as a wash out or a pessary helps a cow with a held cleansing either - to release the placenta or to prevent them going dirty - it only helps if she already has a temperature and metritis.

Cows that hold their cleansing are at a much higher risk of becoming dirty and sick with metritis and if she's sick this does need treating with injectable antibiotics, anti-inflammatories and possibly fluids. We would recommend "watchful waiting" and a daily temperature check is your best bet so you can time treatment to when it is needed.

Injectable oxytocin is often used to help the uterus contract after a difficult calving, caesarean or in a milk fever case - but only a tiny proportion of RFM are due to the uterus not contracting enough - it is much more likely that it is a detachment problem.

Don't forget, oxytocin receptors only last a few hours in the uterus so oxytocin only has an effect at the point of calving.

Does RFM affect her future fertility?

Yes!

  • 5 days longer to start cycling
  • 20 days longer until first serve
  • 4-10% reduction in conception rate

These are definitely cows to add to your "exclusion" list for not being served to sexed semen - the priority for these cows is a pregnancy, not to produce a replacement heifer - so use either a bull or a beef straw.

How many RFM is too many?

We should be aiming for less than 5% of calvings resulting in a held cleansing - any more than that, or if you are having a spate of them - we need to look at the underlying cause as a priority.

WEANING: A seamless transition for your calves?

Weaning can be a risky time for calves as they transition over from a liquid milk diet to solid feed. Weaning should not be an event, but a process that takes weeks to prepare for.

The only thing that should change at weaning is the final reduction in milk volume over that last week; no vaccinations, no disbudding, no mixing groups, no moving sheds, no change to the concentrate, fibre or protein source. Just a gradual decline in milk and a gradual increase in concentrate feeding.

Feed Conversion Efficiency (FCE) in heifers:

The feed conversion rate of newborn calves is the best of their whole life; for every 100g of feed you put in, they can convert it to 50-60g of growth. This drops off after weaning and by the time she is 8 months old 100g of feed only creates 9g of growth.

This window of maximum FCE can make all the difference to heifers - restricting milk replacer to 2 litres twice a day just doesn't give them enough nutrients to grow to their potential. When you push growth rates and feed higher volumes of milk (3+ litres, twice a day at 125g powder per litre) you may have to work a bit harder to get them eating enough concentrate ready for weaning and this tends to mean weaning is delayed and staged.

Whole milk performs differently to milk replacer so you can hit the same maximum growth rates using lower volumes of whole milk, especially with high milk solids. It goes without saying; pasteurised whole milk is best practice, or you will need strict in-parlour protocols for any "ever a positive" Johne's cows to reduce the risk of spreading Johne's disease.

Even though it might seem baby calves aren't taking much concentrate, or straw, or water in the first few days and weeks - all 3 of these are critical for starting the development of the rumen - a process that takes 6 weeks and is key to a successful weaning.

The Rumen:

The rumen in an adult cow is a massive 150 litre vat of bacterial soup that breaks down the food they eat into energy and protein that the cow can absorb. The rumen bacteria and the rumen surface take weeks to respond to a diet change in an adult and if something suddenly changes with her diet then her performance nose dives - and this is no different for a calf.

When a calf is born the rumen is tiny, it's muscles are weak, it has very little blood supply and no capacity to absorb nutrients - milk bypasses it and goes straight into the abomasum - the stomach that digests milk. It is the gradual trickle of nibbled concentrate and straw as well as water in those first few weeks that feeds the right bacteria into the rumen and kick starts the surface changes that mean the rumen can start to absorb food ready for weaning.

The following photos show what the inside of a rumen looks like in calves at 6 weeks old depending on different feeding regimes:

MILK ONLY:

The surface is pale, smooth and weak - this rumen has no capacity to absorb nutrients.

MILK + HAY:

You can see some development of the muscles and surface so this calf would be able to absorb some nutrients from the rumen.

MILK + STRAW + CONCENTRATES:

This rumen has developed strong muscles, the surface is highly developed to absorb the nutrients and the darker colour shows how much blood is at the surface ready to take the nutrients to the liver for processing. This calf would sail through weaning.

If you wean a calf before her rumen is ready to feed her then her growth will stall, her immunity will take a hit and the risk of weaning diseases spiral (cocci, pneumonia, ringworm).

Weaning:

The only thing that should change at weaning is the final reduction in milk volume over that last week; no vaccinations, no disbudding, no mixing groups, no moving sheds, no change to the concentrate or protein source. If the rumen has been well prepared, it just continues to process and digest the increasing amount of solid feed so there is no dip in available nutrients to the calf.

Weaning should only ever take place when the SMALLEST in the group is eating 2kg concentrate a day for 3 days in a row.

Targets:

Monitoring growth rates in young calves doesn't need to be complicated - a weigh band works fine and you don't need to weigh every calf - just follow a few heifers from each batch if you calve all year round, or a few heifers from each week of the block whilst your heifers are being born. The same calves should be followed over time - at a minimum you will need a birth weight, a 4 week weight and a before and after weaning weight to cover the early life growth rates.

Target growth rate: 0.8kg/day

Weaning weight: At least double birth weight

Johne's disease - don't forget your priority culls!

"Priority cull" cows are the most urgent cows to cull out of those infected with Johne’s disease.

Previously we have classified infected cows with repeated test results above 30 as ‘red’ or high risk cows. But there can be a huge difference in infection risk between a cow with a result just over 30 for the first time, compared with a cow with consecutive results over 100 - these repeated, very high result cows are a lot further on in the disease and can be shedding enormous amounts of bacteria into the environment.

The priority cull report will list cows with two consecutive results above 60 and/or one result above 100.
Some real life priority culls - you can see that over time they are repeatedly high in antibodies and likely to be shedding MAP in huge numbers.

These priority cull cows present more of a risk to calves and this late stage Johne's disease will cause a drop in her condition, a drop in yield and make her more susceptible to other diseases.

These cows are ‘losing control’ of the disease and are likely to be shedding large amounts of the Johne's bacteria. They are the highest risk animals in the herd and the ones that should be prioritised for culling.

JOHNE'S TESTING:

A quick reminder!

  1. Don't Johne's test within a couple of months after a TB test
  2. The more we test the more likely we are to pick up the early infections - this means we can serve them to beef and/or plan for a valuable cull
  3. Testing is vital - but identifying positive animals is even more so. A red tag in her ear, a colour code on Uniform, a list of high risk cows by your AI flask will all help to stop infected cows being served to sexed semen
  4. For the summer blocks heading towards serving, make sure you get your Johne's test done so we can get your pre-service risk list together and any new positives can be served to beef

A reminder of the Johne's rules for TSDG herds:

Tesco "red cows" are 2 consecutive high results >30%
You need to make sure you have no more than 2% TESCO red cows in the herd
if you go over 2% "tesco red cows" you will need to either cull before the next recording window, or "retain and test" the positives with a MUCK PCR test - all results NEED TO BE uploaded onto the Authenticate site.
If the PCR result is negative she can stay, if the PCR test is positive she must be culled.

A reminder of the Johne's rules for ARLA 360 / C.A.R.E herds:

from Jan 2023 less than 5% of the herd can be "red cows" - the red cows here are defined as having results over 30% in the last 2 in 4 recordings
from Jan 2023 no PRIORITY CULL COWS can contribute to the saleable milk. This means any cow that's ever been >100% positivity must not contribute to the bulk tank.

A warm welcome to Katie!

Some of you may have met Katie over the past few weeks - we are delighted to welcome her to our HFV team. Katie is originally from Yorkshire but graduated from Liverpool University and is keen to get to know you all!

Katie's mobile is 07507 656747 and her email is katie@haywoodfarmvets.com

GET IN TOUCH:

Paula: 07764 747855 paula@haywoodfarmvets.com

Tom: 07837 291097 tom@haywoodfarmvets.com

Katie: 07507 656747 katie@haywoodfarmvets.com

Enquiries: mail@haywoodfarmvets.com

Website: haywoodfarmvets.com

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