Scours in Calves

A scour outbreak in your replacement heifers can have a devastating effect, not only on the calves but also the farm team.  As always, prevention is better than cure.

1. Keep the environment as "clean as possible".  Don't overcrowd pens, allowing 1.5 sqm/calf and no more than 20 calves/pen.
2. Ensure all calves get a minimum of 2 litres of fresh, good quality first-milking colostrum within 12 hours of being born and another 2 litres in the next 12 hours.
3. Ensure good routine in the calf shed, with milk at a similar temperature and consistency at each feed.

If you start to see calves beginning to scour:

1. Spread calves out as much as possible, either across pens or out into clean paddocks, weather permitting.
2. Consider getting 10 blood samples taken from 2-8 day old calves to check if they are getting enough colostrum.
3. Increase disinfection on the calf pens, calf trailer and feeding equipment.  Don't forget your boots and clothing too!
4. Get professional advice!
5. Ensure all scouring calves are getting adequate fluids each day.  This is 6-8 litres of fluid/day.
6. Critically sick calves that can't get up may need IV fluids and/or bicarbonate to get them up again.  I recently treated a calf which was very close to death with bicarbonate into the vein and had it up and drinking within 3 hours.

Salmonella brandenburg - Abortions in Cattle

Salmonella brandenburg abortions were first seen in sheep in mid-Canterbury back in 1996.  Since then a cyclical pattern has been seen, with outbreaks mainly in Otago and Southland.  Cases in cattle have been sporadically seen, but recently we have seen a concerning trend of increasing numbers, culminating in around five of our farms this year having confirmed Brandenburg abortions in their cattle.  The aborting cows typically present as off-colour for 1-3 days before calving a rotten calf (often with assistance).  These have been up to 50 days early, and many of the cows aren't coming into milk .  Scouring and death can also occur, and scours can also occur in calves.  Salmonella is highly zoonotic (contagious to humans) so good hygiene should be maintained in any cases with suspicious signs.  Individually affected cows should be treated with oxytetracyclines, anti-inflammatories, and fluids.  Aborting animals will shed high numbers of bacteria, so are an important source of transfer and environmental contamination.

Transfer of Salmonella brandenburg onto new farms is likely to occur in one of three ways:

• Firstly infected cows can become non-clinical latent shedders.  Purchase of these latent shedders can bring the disease onto your farm.
• Secondly environmental contamination of pasture/yards/waterways/trucks can lead to transfer.  Salmonella is likely to last just 1 week in bright, exposed, sunny conditions, but can last between 4 months to 2 years in covered areas (including cattleyard dust).
• Finally it is thought that scavenger birds (such as seagulls) can transfer the bacteria between properties.

One of the main control measures currently being used is vaccination with Salvexin+B, along with picking up dead calves, reducing stress, and avoiding areas of high contamination (including cleaning trailers etc).  Because Brandenburg is an emerging disease there is no research into vaccination in the face of an outbreak, however anecdotally it has been reported to decrease the incidence of abortions and death.  The majority of interventions have had no ill effect on the cows, however there has been one incidence of downer cows post-vaccination so any decision to vaccinate should be discussed fully with your veterinarian to weigh up the pros and cons.  As with any disease, vaccination prior to exposure is better than in the face of an outbreak, so future vaccination programmes will need to be implemented on at-risk farms.

If you are seeing any similar cases contact your prime vet to make a plan for diagnosis and control.

Preventing Metabolic Problems

Getting magnesium supplementation right over spring is likely to have the greatest effect on reducing the incidence of metabolic problems.

The cow is totally dependent on what magnesium is supplied in their daily diet.  The magnesium  content of spring grass is relatively low and only a small percentage of this is absorbed by the cow.  One of the main factors affecting availability of magnesium is herbage potassium levels.  High pasture potassium level causes significant decline in absorbable magnesium, particularly in spring when herbage magnesium is at its lowest.

Start supplementing with magnesium daily for 3-4 weeks pre-calving.

The best way to achieve the required dietary magnesium concentration pre-calving is to add 60 grams Mag C or Mag S/cow/day into the water supply and dust pasture/silage with 50-70 grams Mag Oxide/cow/day as well.

If the herd is experiencing more than a 3% incidence of milk fever despite sufficient magnesium supplementation then colostrum cows can receive calcium supplementation via lime flour at 200g/cow/day dusted on the break.  Lime flour can continue to the milkers at 100g/cow/day for the first 6 weeks after calving if required.

To avoid metabolic problems:

1. Maintain adequate dry matter intakes over the spring period
2. Supplement with sufficient magnesium
3. Avoid grazing potassium rich effluent paddocks with springers and colostrum cows
4. Avoid excess applications of potassium rich fertiliser during the months of June - October.
5. Blood test mature cows on day 3-4 of the colostrum period for metabolic profile.

Dry Cow Therapy

There is only one outcome we are interested in when we consider dry cow therapy and that is to have as many cows as possible calving without an infection.  To achieve this, any cows that are infected at dry off need to have that infection cured and not acquire a new infection.  Cows that are not infected at dry off, need to be protected against new infection.  For the majority of cows dried off from now onwards, Cepravin will provide adequate protection against new infection for the duration of the dry period and obviously cure existing infection.  There is also the option for cows that are not infected to use Teatseal to protect against new infection for the entire dry period.  There are rules based on the history of the cow that allow us to be very confident that a cow is not infected at dry off.

A mixed age cow can be considered not infected at dry off if all four herd tests were less than 150,000 and there were no cases of mastitis.  A first lactation heifer can be considered not infected if all four herd tests were less than 120,000 and there were no cases of mastitis.  If the BMSCC is under control and not rising at the end of the season these rules allow a significant number of cows on many farms this year to be protected for the whole of the dry period with Teatseal.

Cow BCS and Preparing for Winter

The greater majority of herds which we see going off farm on a winter grazing contract are budgeted on cows being offered a standard 14kgDM/cow day.  Is this figure relevant to what your herd requires to meet target at calving?  If they will need more can your grazier accommodate the number of cows you plan to send?

• 1 BCS gain in a 480kg dry cow will require 2100MJME over and above maintenance and pregnancy requirements.
• Therefore the difference between what a BCS 4.0 cow and a BCS 5.0 cow are offered over a 60 day dry period is about 240kgDM (or 4kgDM/day).

Our practice operates a comprehensive BCSing service whereby individual animals can be scored and with due to calve dates factored in calculate daily energy requirements to reach targets over the winter.

If performed in April, light cows can be identified for preferential feeding, OAD milking or staggered dry off depending on your system before cows are dried off.  The big advantage of doing this is that cows can be wintered in mobs based on due to calve date and not BCS as the herd profile is fairly even before dry off.