Cryptosporidium provides a real challenge for many calf-rearers. Animals infected with the parasite can shed millions of oocysts into the environment, resulting in a high potential of infecting other animals and farm staff.
Dealing with animals infected with Cryptosporidium is not only a time consuming job, but also has been associated with reduced weight gain over the first 6 months of life (1). This has been shown previously to delay time in reaching mating weights and therefore AFC (2).
Calves which have not received sufficient colostrum have been shown to be at increased risk of disease and mortality. Calves are thought to become infected very quickly after birth and so will not have time to mount their own immune response - they rely on antibodies from colostrum at this stage.
Vaccination of dams to boost Cryptosporidium antibody levels has been looked at in experimental settings, however no product is currently commercially available.
Identify infection source
Identifying the main source of infection in calves on your farm can help to assess where best to target your efforts, and prevent a lot of head scratching! Not all Cryptosporidium are the same and it can be useful to genotype the cryptosporidium cows are shedding, vs those the calves are shedding.
If they do not match, then adult cattle are unlikely to be the main source of infection in calves, and more efforts should be made to look at calf husbandry and hygiene.
Once infection is established in calves, transmission is rapid. Disinfecting the environment is paramount to reduce infection rates and levels in calves. Many disinfectants are ineffective at killing Cryptosporidium.
Hydrogen peroxide based disinfectants are the most effective. KENO-COX has been shown to have 7 days efficacy post application. Another alternative is 3% Hydrogen Peroxide.
Top tips for disinfecting:
Use a hydrogen peroxide based disinfectant
Thoroughly clean surfaces before applying disinfectant, to remove all faecal material
Make up disinfectant as fresh as possible before applying to surfaces
Some products are available to reduce shedding of Cryptosporidium. These can be antibiotic products (these are not recommended by the author) or halofuginone. This should be given daily for the first 7 days of life to reduce shedding. This, combined with meticulous disinfection may allow farms to achieve complete erradication of Cryptosporidium in their calves.
It is also recommended for calves to not mix in age groups >2 weeks apart, as older calves are a high risk infection source for neonatal calves.
Shaw HJ. Cryptosporidium in Calves. University of Edinburgh 2018
Bazeley KJ, Barrett DC, Williams PD, Reyher KK. Measuring the growth rate of UK dairy heifers to improve future productivity. Vet J. 2016 Jun;212:9-14. doi: 10.1016/j.tvjl.2015.10.043. Epub 2015 Oct 27. PMID: 27256019.