Scours in calves - Nicola Neal BVSc

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 so here are a few simple ways to decrease the chance of getting scours.

1. Keep the environment as 'clean as possible'. Do not overcrowd pens, allowing 1.5sqm/calf and no more than 20 calves/pen. Try not to do any more than 2 batches of calves through each pen. Disinfect pens regularly with Virkon and top-up or change bedding if it starts ti get mucky.
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. This may require you to pick up calves more than once daily or tube calves in the paddock in the afternoon.
3. Ensure good routine in the calf shed, with milk at a similar temperature and consistency at each feed (i.e. not colostrum at one feed, then milk powder at the next), consistent knowledgeable staff and well maintained, hygienic feeding equipment.

If you start to see calves beginning to scour, here are some ideas to maximise recovery and reduce any further sick ones:

1. Spread calves out as much as possible, either across pens or out into clean paddocks, weather permitting. Ideally paddocks would have some shelter, as turning out calves can be stressful and make a scour problem worse.
2. Consider getting 10 blood samples taken from 2-8 day old calves to check if they are getting enough colostrum, early enough for it to be absorbed properly.
3. Increase disinfection of the calf pens, calf trailer and feeding equipment. Do not forget your boots and clothing too!
4. Get professional advice! There are many effective treatment and management techniques out there, depending on the specific cause of your outbreak.
5. Ensure all scouring calves are getting adequate fluids each day. This is 6-8 litres of fluid/day, with both good quality electrolytes and milk being fed at different times during the 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. Do not give up too easily as we can often get these valuable replacements right again!

Transition Management of Cows

For many farmers when we say 'cow transition' they immediately think about the dietary change from crop to grass when the cows come home. In fact transition is a whole lot bigger than this.

In a matter of days between the period before and after calving, a cow's:

• energy requirements almost double
• she starts making milk
• about 30-40 grams of calcium are lost through the milk daily
• she has a greater demand for blood glucose, which requires a change in metabolism

To accomodate these changes well, the cows must:

• eat more
• increase the size of the intestines (absorptive area)
• increase the size of the liver (to meet demands of increased metabolism and drive appetite)
• increase the amount of mammary tissue
• mobilise bone calcium (70% of calcium in the colostrum comes from the skeleton!)
• increase dietary absorption of calcium through the gut
• mobilise body tissues for extra energy (but not too much!)

When cows are transitioned poorly, they are :

• more prone to ketosis
• more prone to mastitis
• more prone to milk fever
• more prone to metritis
• will not peak as high or as early in milk production
• lose more weight post-calving
• have a poorer reproductive performance

So to get optimal results from a cow this season, she needs to reach a BCS of 5.0-5.5 by 3-4 weeks before she calves, ideally be on a slight negative energy balance during the last 3-4 weeks of gestation (this will pre-condition the liver to the post calving demands), have increased feed quality over the last few days before she calves (as voluntary dry matter intakes tend to drop), be supplemented with magnesium for at least 3-4 weeks before she calves, be on at least 70% of the post-calving diet for 7-10 days before she calves and finally be offered high quality and ab-lib feeding immediately after calving.

By definition, the transition period in a cow is the period between 3 weeks pre-calve and 3 weeks post-calve. Look after them well over this time - it will make the difference between an okay season and a great one.

Calf Health and Management

We are more and more aware of the impact our heifers will have on the future success of our herd. Getting valuable replacement heifers off on the right foot in the pre-weaning period is a crucial step in bringing in top quality,  well grown heifers as two year olds.

The Veterinary Centre can offer a full range of calf health and management advice.

Dairy veterinarian and veteran calf rearer Nicola Neal can assist with the set up and design pf your calf shed systems and management. Nicola completed a Masters paper in "Calf Health, Disease and Management" last year and is keen to apply some practical on farm knowledge, along with the latest scientific advice. This service is tailored to suit the individual farm and could include on farm training of calf rearers', developing quality assurance systems wen you can not be there to supervise, developing calf health plans and making the most of facilities.

Do not wait for a problem to develop in the third week of calving when you have not got the time to deal with it, call now to book a time to review you calf shed systems.

Setting Your Herd Up for Success

If significant BCS gain is required over the dry period be realistic about what you need to feed your cows. As little body condition can be gained in the last month of gestation, feed maximally in the month of June to try and maximise this gain.

A cow putting on 1 BCS in the month of June will require about 7kg DM/day above maintenance and pregnancy requirements compared to a cow already at target.

• For every BCS below a 5 at point of calving, cows will tend to produce 12-20kg of MS less for the season.
• For every BCS below a 5 at point of calving cows will tend to take an additional 10 days to resume cycling.
• Cows which do not have a pre-mate heat will have 10% lower conception rates when finally mated.
• The target BCS for an individual cow at point of calving is 5.0-5.5. This is an extremely good looking cow. Her pin bones are no longer visible (at all!), the rump is filled in, the hips are rounded, the spine is not visible (at all!), the short ribs are rounded and the long ribs are not visible (at all!).
• It is thought that a large proportion of cows in New Zealand calve below target BCS.

Nitrate Toxicity Alert

Brassicas (Kale, Chou, Rape, Turnips and Swedes), fodderbeet, Italian ryegrass and oats can all produce nitrate toxicity. Of this group, rape is the most notorious - winter rape crops continue to gain popularity in this area for heifer grazing.

Before introducing animals to crop this June, we urge that it be tested first.  Nitrate test kits can be purchased from any of our clinics, representing a cheap investment. Alternatively bring in samples to be tested by our staff.