Prevention of common infectious & parasitic diseases affecting dairy beef calves

Dairy beef calves can be susceptible to a number of infectious & parasitic diseases. Niamh Field has advice and information on the prevention and management of coccidiosis, gutworm, lungworm and viral pneumonia.

Parasitic infections

Coccidiosis

Coccidiosis is a disease of the intestine and is often seen in calves ranging in age from 3 weeks to six months of age. The disease is caused by a tiny parasitic organism that disrupts the function of the gut. Coccidial infection depends on the level of challenge to the calf and the state of their immunity. Clinical cases of the disease present with watery diarrhoea containing blood and mucous; often the calf may be seen straining to pass faeces and in severe cases, scour may contain strips of the intestinal lining. Subclinical coccidiosis is also very common, and may occur when the challenge with coccidia is lower, or if the calf has some level of immune protection again it. Sub-clinical signs usually are decreased appetite and reduced growth performance.

Consult with your herd veterinarian who will guide on appropriate sampling and treatment of the disease on your farm. Further information is available at Animal health Ireland who have published very good guidelines on the management of coccidiosis in calves.

Gutworm

To minimise exposure to gutworm when calves are first turned out, they should be turned out onto low risk pasture if available, i.e. no cattle on it in the previous year or adult cattle only. If calves are turned out onto high risk pasture, such as fields used as permanent calf paddocks, strategic dosing with anthelmintics may be required within the first 8 weeks of grazing to reduce worm burdens.   

In order to maximise growth rates while reducing anthelmintic usage, regular weighing of calves combined with monitoring of faecal worm egg counts is recommended.  In order to get a picture of the worm burden in a group of calves, faecal samples should be taken from 10-15 calves. These samples can be pooled with up to 5 calves per pool.

Daily liveweight gain of less than 0.6-0.7kg per day, together with more than 200 worm eggs per gram of faeces is an indication of poor growth performance and treatment with a worm dose is required.

Lungworm

Lungworm can cause severe respiratory problems in first grazing season calves as they have no immunity when first turned out. The period of risk for lungworm is late summer, but it can cause disease as early as May under certain conditions. The key element in managing lungworm in calves is careful monitoring for clinical signs, particularly in the second half of the grazing season. Calves should be moved onto silage aftergrass where available to reduce the risk. The main clinical sign is coughing, initially seen only when calves are moved, but progressing to a persistent cough. The entire group of calves should be dosed for lungworm when clinical signs appear.

Viral pneumonia

When calves are housed in the autumn, a combination of stress, close proximity to other animals and inadequate shed ventilation may lead to outbreaks of viral pneumonia. Viruses affecting calves include BoHV-1 (IBR), BRS-V, and PI-3V. A case of pneumonia can have a significant impact on the future performance of the affected animal, so preventative strategies are much preferred to treating cases as they arise.

Monitoring

Clinical signs of viral pneumonia include dullness, increased breathing rate, nasal and eye discharge, fever and coughing. Temperatures over 39.5°C indicate a fever in calves. Where any of these clinical signs are observed, advice from the veterinary practitioner for the herd should be sought.

Prevention

1. Reducing stress on calves around the time of housing is very important in preventing pneumonia; where possible husbandry management tasks such as castration and dosing should be spread out and not done at the same time as housing calves for the first time.
2. Avoid mixing of animals from different groups at housing, as this can increase stress and also lead to transmission of viruses between groups.
3. Vaccination is a useful tool to reduce the risk of outbreaks of viral pneumonia. To maximise the effectiveness of a vaccination programme, it is recommended to identify the viruses that are causing the outbreaks in a particular herd. Your veterinary practitioner should be consulted to advise on this. The primary course of the vaccine should be completed in the calves at least two weeks before they are housed.
4. Review the ventilation of cattle sheds with your veterinary practitioner or another qualified adviser, and identify options for improving ventilation where required. Making changes to air inlets and outlets does not always require expensive investment, and simple changes can make a significant impact on the air quality in sheds.

Further information is available here