Yersinia

Each summer we investigate several cases of calves scouring post weaning. While there are many causes of diarrhoea in weaned calves i.e. parasitic enteritis, Salmonella, and BVD, we regularly diagnose Yersinia, which is a bacteria that causes diarrhoea. We often see Yersinia ‘roll’ through a mob of calves - with a small number of calves being affected at any one time. Treatment is aimed at correcting dehydration and administration of antibiotics. Prognosis is usually good except in advanced cases.

There is circumstantial evidence that Yersinia is often associated with concurrent disease i.e. BVD, parasite burden, low trace element status - especially selenium and copper. Remember - that Yersina (both Y. pseudotuberculosis and Y. enterocolitica) are zoonotic - and hence are a common cause of food poisoning in people. Keep the hygiene standards high if you are dealing with scouring animals!

Please contact the clinic if you are concerned about ill thrift or scouring in your weaned calves.

When lame cows get out of control

We are visiting a few farms at the moment where lame cow numbers have got out of control. The smart money is on picking up a foot ASAP and correcting any lesions before they get too bad. If lame cows are left they’re likely to eat less, produce less milk, have lower repro rates, and ultimately have a greater risk of being culled.

On some farms, however, we are seeing lame cow mobs of 30-100+ cows. By this stage farmers are struggling with time, and the problem often seems insurmountable. Human nature takes over, and so these cows are often left in a close paddock under the “wait and see” treatment regime, rather than being picked up and treated. If you are in this boat, or want to avoid getting there then we have three options to help:

• Staff Training: we can come out and teach your staff members about how to treat lame cows. This can help spread the workload across more people on farm.

• Vets to Treat: we can send out a team of vets (if available) to treat enough cows to get the mob down to a manageable level. To enable multiple vets to work at a time these animals would need to be treated on the platform/herringbone (rather than a race). Budget on a treatment rate of around 4-6 cows per hour (per vet).

• Healthy-Hoof Lame Cow Prevention Training: Andrew, Luke and Ryan are all trained Healthy Hoof providers and can come out on farm to teach staff about how their actions (i.e. gate use, animal handling) can increase or decrease lameness. We have had some amazing results on farms following these courses, with dramatic reductions in lameness just from a change in staff attitude and knowledge around cow handling. A more in-depth package is also available looking at diagnosing track and shed issues that are having an influence.

The hidden costs of lameness can quickly mount up, and only get worse the longer they are left. Traditionally we’ve used an industry figure of around $200 per lame cow. However DairyNZ recently proposed a figure of $500 if you have to start taking cows out of the vat. If you think your lameness issues may be spiraling out of control then give one of our vets a call and we can work out how we can best help you get back on top of the situation.

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.

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%.

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.