“Why do I get so many sick calves in the second half of calving? I do exactly the same things as at the start but suddenly get outbreaks of diarrhoea.”
If you are rearing calves, it is likely you have already had a considerable amount of calves through your sheds. The more calves that have been through your pens, the more bugs are likely to be present and the greater chance of infection.
You are also not as fresh as you were at the start of the season and circumstances may cause you to make unplanned changes. All of these things can affect your calves health –
NOW is the time to check that your calf rearing plan is still working for you. Use our list below as a checklist and catch up with your vet for a hand if you need help.
Calf scour checklist
1. Are calves getting adequate immunity?
- If not, they will have failure of passive transfer (FPT) leaving them vulnerable to disease. FPT can be diagnosed by blood sample.
- Is the colostrum good enough? Check the antibody level in colostrum using a Brix meter. Gold colostrum should have a Brix reading of 22% or more. You may be surprised to know that heifer colostrum can often have higher brix levels than high producing, older cows.
- Are newborns getting first milking “gold” colostrum? Antibody levels in the cow drop dramatically after the first milking so the second, third and subsequent milkings will have fewer and fewer antibodies. Mixing first milking colostrum with second, third and fourth etc. will dilute the antibody level in the milk and reduce the amount newborn calves get.
- Are they getting colostrum soon enough? The gut closes and can’t absorb antibodies within 16 hours of birth. Calves need two feeds before the gut closes.
- Are they getting enough colostrum? Calves need to be fed 4-6L of colostrum within 12 hours of birth, split across 2 feeds (their stomach can only hold ~2L in a single feed).
- Have you checked your pooled colostrum is good quality? You can test the E. coli levels with a milk sample from your pooled colostrum. If E. coli levels are high if will affect the quality of the colostrum and you may be better off starting a new batch of milk.
2. Has there been a change in feed?
Have you changed from colostrum to whole milk or pooled colostrum to milk powder? The calf’s gut is very sensitive to changes in feed. Keep the feeding routine as consistent as possible including the same time of day and same temperature.
When changing feed try to make it gradual, particularly when changing from whole milk to milk powder feeding. Try to only change the diet by 30% each week. Changing feed too quickly or chopping and changing feeds can upset the balance of gut bacteria.
3. Are you optimising calf health?
- Calves need access to ad lib clean fresh water in addition to the milk they drink. Scouring calves also need electrolytes as they can rapidly deteriorate from dehydration as they lose so much water through diarrhoea.
- Are you promoting a healthy rumen by offering high quality meal and hay from day one.
- Are you practicing good hygiene? You need a dedicated sick calf area. Disinfect pens regularly as well as boots and equipment used in calf areas. Make sure calf milk feeders are cleaned out thoroughly and ensure teats are replaced regularly.
- Are you topping up the bedding regularly, particularly after 4-6 weeks when the infection pressure builds up in the shed?
- Ensure calves get their vaccinations as soon as they are due.
4. Have you tested to see what you are dealing with?
There are many different bugs that cause scours including E. coli, rotavirus, cryptococcus, coccidia. Most of these won’t respond to antibiotics because they are not bacteria. Different bugs are more likely to cause problems at different ages.
Taking some faecal samples will let you know what bug you are dealing with and therefore figure a treatment and prevention plan. For example, with salmonella outbreaks vaccination may be worthwhile.
Calf scours can be heart wrenching and time consuming to deal with. Reach out if you need any help with your calf rearing systems.