New Calf Disease - Sporadic Bovine Encephalitis (SBE)

Two years ago a new calf disease was reported in NZ. This was first seen on several farms in the Canterbury area and then more latterly in the Manawatu. To date there have been around 15 properties that have had a confirmed diagnosis in NZ.

The disease is caused by the bacterium Chlamydia pecorum (which was first found in NZ in the goat population about 30 years ago).

Affected calves develop neurological symptoms which include seizures and hind limb ataxia (wobbly in back legs), depression and an inability to stand. The progression of the disease is quite rapid - within 24-48 hours healthy calves may no longer be able to stand or want to suckle. The spread of infection through a mob of calves seems to be quite rapid - a high percentage of calves in the mob may have high temperatures without displaying significant illness.

The brain, heart and abdominal organs can all be affected. The pathology to the heart when viewed at post-mortem can be very dramatic (see below). The pericardium (sack around the heart) is thickened and full of fibrin (see arrow).

In September we diagnosed the first case in our practice. The affected farm has lost around 20 calves out of 350 reared, but it is probable that many more would have died had treatment not been provided. Early treatment is required to be successful. The rearer’s commented that they had not realised how sick the whole mob was until they started playing again a few days post-treatment.

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CIDR Program 2018

Many herd owners have already booked in dates for treatment of anoestrus/non-cycling cows. There has been a huge rush on programmes starting before P.S.M., due to last years disappointing reproductive outcomes on many farms. Please ensure you plan/notify your AI technician immediately to avoid clashes.

This year’s CIDR program does not differ from last year’s programme. Please note the following:

  • A CIDR program takes 10 days to complete from CIDR insertion to insemination - i.e. a cow CIDRed on the 12th of October will be inseminated on the 22nd of October (up to 50% of cows may cycle on day -1 i.e. one day earlier).

  • Expect an average of 17% of cows to be on heat on the morning of day -1 (range 5-32%). Mate these cows immediately.

  • A further 20-30% may come on heat between morning and afternoon on day -1. It is an option to get the technician in again that evening if desired.

  • The rest of the cows should be blanket inseminated 8-20 hours after the final GnRH injection.

  • We recommend giving eCG (Pregnecol) at the time of CIDR removal/PG injection. This will increase pregnancy rates by a further 5-7%.

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The First Month of Lactation - Minimising Ketosis

A good start to a cow's season requires careful management through the springer and colostrum period to ensure that she maintains a high dry matter intake.  Initial focus should be placed on prevention of metabolic disease, optimising immune function, adequate feed allocation and manipulating cow behaviour.

However, the first month of lactation beyond the colostrum mob is still very critical.  Most cows will spend this period in negative energy balance i.e. more energy is leaving their system than coming in and therefore will lose body condition.  This is why providing consistently high feed quality is imperative.  We are already seeing many farms that are struggling to manage very high pre-graze covers due to good growth rates through the winter. These are impacting on voluntary intakes and may have lower ME.

Cows in significant negative energy balance may develop clinical or sub-clinical ketosis.  Ketones are a by-product of inefficient fat break down and have a side effect of further appetite suppression. 

Cows which are well fed/have a good appetite in the first month of lactation, will lose less weight and have better mating performance.  Try some of the following:

  • Optimal pre-graze covers of 3,000 to 3,400 kgDM/ha in the first round will ensure good quality and easy harvest for the cow.
  • Aim to get your milking cows eating 4% of body weight in DM ASAP.
  • Use monensin (Rumenox/Rumensin Max), to increase feed conversion efficiency, by driving proprionate production.  Clinical trials show boost in milk protein production and far less BCS loss.  Use strategically from calving up until mating.
  • Internal parasites - the biggest impact these have is on appetite suppression.  Almost all farms will have high levels of over wintered larvae this year.  We have seen cases of clinical disease from worms in R1 and R2's in the last month.  Drench your herd by early September.
  • Vitamin B12 - is a requirement for energy extraction.  Deficient cows will lose appetite.  We see serum B12 levels drop at the same time as spring grass goes lush.  This is partly due to rapid transit times through the gut impeding B12 absorption.  A good rule of thumb is when faeces starts becoming liquid look to give Vitamin B12.

Feeding Acidified Milk to Calves

There has been a lot of discussion in the farming community in the last month about the use of pasteurisation and acidification of milk to reduce the risk of Mycoplasma bovis (M. bovis) in your herd.  Please be aware that these techniques will not stop M. bovis getting into your calves if it already exists in your herd (i.e. if they have already drunk from their dam).  Pasteurisation or acidification may slow the spread within a group of calves that are fed pooled colostrum, but the status of the group would largely remain unchanged - i.e. positive.

Pasteurisation of milk does kill M. bovis, but a big benefit is a reduction in the load of any Johnes bacteria it may contain.  Pasteurisation is a very good practice for Johnes prevention/control in a problematic herd.

Acidification of calf milk will provide some other health benefits to calves.  Dropping the pH of milk to between 4 and 5, will prevent the overgrowth of E.coli in stored colostrum thus reducing scour risk and increasing the feed conversion ratio (M. bovis will not survive a pH environment of 4 for more than an hour and pH5 for more than 8 hours).

There are two recommended methods for acidification of milk.  The most tried and tested by using yoghurt cultures.  If you use a live Lactobacillus yoghurt culture this will bring down the pH to 4.5.  Start with 2-3L of fresh clean milk and add a live Acidophilus culture and allow to ferment overnight.  The next day mix them into 2 x 20L containers of fresh warm milk and allow to ferment again in a warm environment.  This then acts as a base culture for milk added daily.

The other option is the addition of citric acid - refer to DairyNZ website for instruction on doing this.  The aim is to achieve a milk pH of 4.5.  Calculation and mixing has to be quite precise to avoid milk from clotting or causing calf refusal. 

Potassium sorbate as a preservative, remains as excellent short-term preservative for colostrum.

Lifting Downer Cows

Calving is just around the corner so inevitably there will be down cows.  When you have decided to lift a down cow it has to be effective.  Hip clamps are meant to assist cows to their feet, they aren't for suspending cows in the air.

  • Firstly make sure that there is a reasonable chance the cow will stand.  Is she bright and has a bit of go about her?
  • Have some padding around the hip clamps, plastic rubber etc.  This is really important when managing a long term downer.  Ensure her skin isn't getting damaged.
  • If she is weak/struggling in the front end use a strop under the brisket.  It is good practice to use this anyway.  See diagram:
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  • If she refuses to stand, stop straight away.  Check your diagnosis, or get help:  Waimate 0800 VET 999, Oamaru 0800 VET 111.
  • Keep hip clamps on for a maximum of 10 minutes.  If she has her feet on the ground but not fully weight bearing keep going for a maximum of 5 minutes then stop.
  • Whenever cows are in hip clamps they must be supervised.
  • Correct placement of hip lifters and brisket strap.