CALF PNEUMONIA
- management of chronic disease

• Previous work has shown that financial losses are running at between £20 and £80 per calf exposed, due to reduced weight gain, increased labour, and vet costs. The definition of a calf 'exposed' is any animal that shares the same airspace as an animal with symptoms, or can reasonably be expected to have contact. Note that vet costs are approximately 40% of all costs and therefore hidden financial losses can be high. A quick calculation will give you an idea of the financial value of getting the pneumonia under control.
• There are at least 6 viruses and pathogens in the UK that are commonly associated with calf pneumonia. Previous work shows that ALL herds have at least one of the pathogens active within a herd, which implies that the presence of the pathogens is not necessarily the main factor that controls the presence or absence of symptoms in calves. Note that the presence of bovine viral diarrhea (BVD) in a herd can precipitate a pneumonia outbreak.
• The management of calf pneumonia is down to management of the various risk factors involved;

• immune status,
• exposure,
• building factors, and
• other environmental stressors.

It is unlikely that you will see a major improvement in performance by tackling only one area.

Immune status
• Immune status 1. Calf immunity starts with the dam. If the herd has a variety of health niggles it may be that mineral status is not balanced (not uncommon). Background serology is good practice for disease management under any system, and with organic stock will provide evidence to support any need for inputs. In the short term organic supplements can be given but note that most imbalances will originate from problems at soil level. Long-term solutions may require changes to soil management.	Calf immunity starts with the dam
• Immune status 2. Good colostrum management is essential; not usually a problem in suckler herds but should be checked in dairy herds. Thereafter in the face of the relevant pathogens circulating within the herd vaccination is probably required. Again serology is essential to ensure targeted treatment. Vaccination must be timely otherwise you will have spent money on getting eg. 95% of calves done correctly leaving a nice 5% to continue shedding active virus and bacteria around the herd.
Exposure
• Exposure is complex but there is a need to manage the dose of any viable bacteria or viruses that impact on any one animal. Thereafter there is a need to manage the timing of exposure so that an individual animal is not exposed at a time when it is under stress from other factors. The critical factors for managing dose are stocking density and ventilation. • Mixing of stock is critical for two reasons; the first is that mixing is a factor that increases stress on individual animals, if only for a short period. During that period the competence of the immune system is reduced, and if viruses and bacteria are circulating within the animal they have an opportunity to multiply within that animal. More bugs means a greater risk of the animal developing symptoms; the delicate balance between the immune system and the pathogens will turn in favour of the pathogens. Thus more disease. • Mixing different ages means that calves at different stages of the immunity/pathogen battle are required to share the same breathing space. Older calves may be coping but can still be shedding active virus that can be breathed in by younger animals. The ideal is all in/all out systems of housing, but there must be recognition that if stock are mixed there will be an increased risk of pneumonia symptoms.
Building factors
Stocking density: Smoke test of ventilation Doorways are not good inlets Outlets should be in the roof: a slotted roof	• Building factors 1. All buildings have a finite ventilation capacity, which means that overstocking of a building's ventilation will cause an increase in air moisture levels (and consequently an increase in the survival time of airborne bacteria and viruses) and a reduction in the movement of clean incoming air to remove airborne bacteria and ammonia (both of which have been shown to increase the prevalence of respiratory disease). Approximately 50% of all naturally ventilated buildings investigated in research projects do not supply adequate airflow for the weight of cattle housed. The main problems are a lack of suitable inlets and outlets. Inlet areas should be twice the outlet areas Outlets should be in the roof to allow the stack effect to work and to release the warm air + exhaled pathogens to exit the building Doors are not good inlets; they do not reduce wind speeds (ie create drafts), give fresh air in only one area, and are closed too easily. Adequate ventilation is a long term design solution. Seek professional advice
• Building factors 2. Moisture management: keep all drains clear, gutters cleaned, bedding dry, especially during the high risk periods of low external wind speed (mid-October and late December/early January. Use the best quality bedding straw during high risk periods as the fungal spores in mouldy straw represent another pressure on the respiratory sytem. • Sick pens. In calf pneumonia there is often a relationship between the environment and a case or cases of pneumonia. It is not entirely logical to treat a sick calf and leave it in the same pen because The environment of that pen may have contributed to that calf having reduced immune competence (damp/underventilated/overstocked etc) The effectiveness of any medication will be reduced if the environmental stressors are significant. A sick calf is often shedding high levels of active virus and bacteria and therefore increases the threat to penmates A sick calf is less able to maintain its status with penmates and is therefore least able to get the 'best' part of the pen. A sick calf will return to health quicker, and therefore lose less financial value, if it is kept in dry, clean conditions, possibly with added heat. This is rarely provided at group pen level.
Other environmental stressors.
It is valuable to try and manage the stress on all cattle because there is a high probability that they are exposed to circulating virsuses and bacteria at some time. The aim is to reduce the number of stressors at any one time, and especially during periods of high risk such as changing housing, treatment (including vaccination), and changes in weather. Items to consider are; • Change of diet • Dehorning • Drafts and damp bedding

Supported by the Kintail Land Research Foundation

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