24 November 1995

Unit breathes easier…

After a bout of pneumonia at ADASRosemaunds veal demonstration unit, preventative measures have been stepped up.

Jessica Buss reports

REDUCING the risk of pneumonia requires more than adequate space and ventilation.

Calves often succumb to infection in damp, still weather, such as this autumn, warns Mervyn Davies, livestock research team manager at ADAS Rosemaund, Hereford.

He advises careful management to avoid stress, adequate colostrum, and in some cases vaccinations to avoid risk of infection. This is greatest at the three- to six-month stage.

Usually, calves at Rosemaund are reared on a silage beef system. They arrive at the farm from contract rearers at three-months-old. However, this year a batch of 72 calves was kept on the unit from two weeks old in the veal demonstration unit, set up in autumn.

These calves suffered with respiratory problems and although 40 were treated, two died. Mr Davies estimates the cost of the outbreak at over £10 a calf treated, including vet bills, farm labour and lost animal performance.

He decided against vaccination because no single pneumonia organism was identified. But when one had been found in previous outbreaks, calves were vaccinated.

Vaccinations used

"Vaccination is seen as a second line of attack but is used if other measures prove inadequate. After vaccination there were still animals that needed individual treatment, but it helped reduce the pneumonia."

However, he considers routine vaccination for pneumonia too expensive to justify.

"A programme to safeguard calves against IBR, P13 and RSV costs £10-12 an animal," he says.

Mr Davies stresses that purchased calves are at increased risk of pneumonia because they are not reared on their farm of origin.

Reducing the risk of pneumonia starts when calves are bought at two weeks old. "Calves are checked to ensure they are healthy before they go to rearers, says Mr Davies.

"When we suspect they have had insufficient colostrum they are rejected to prevent infections in healthy calves."

The veal calves and those returning from contract rearers at three months old are housed in an open-fronted mono-pitch shed until six months of age.

"Ideally the shed would be sited at the top of the hill and the front would be further from other buildings," he says. "This would improve natural ventilation."

Mr Davies felt improving the ventilation in the building would help so a ventilation fan was installed this summer.

"A fan blows air up a polythene tube with holes. The gentle air-flow that keeps air moving in the building complements the natural ventilation without causing draught. This system cost about £500, but if we save two calves it will pay for it."

Calves are kept in groups of 10, so they have adequate air space. Furthermore, their pens have full height divisions so airspace is not shared between groups of animals .

Calfs area

"Each calf has 3.2sq m of floor area and 15cu m of air space in the pen," he says. "The back of the pens has double Yorkshire boarding that slides to allow ventilation to be adjusted.

"These are normally fully open except when wind is causing a draught on small calves.

"Bedding can also help to reduce draughts and keeps the calves dry.

Dry bedding is important to reduce the humidity and ammonia vapour which makes the air stale."

Another factor that causes stress is a sudden change in feeding.

"Beef calves are weaned by the contract rearers at five to six weeks old and then fed a coarse calf ration, hay and straw. When they arrive at Rosemaund we offer the same ration.

"This is replaced gradually with a home mix of barley and protein, plus grass silage over six weeks. Concentrates are fed twice a day, so the stockman sees the calves frequently and can spot signs of ill-health early on."


Floor/air space needed for growing cattle

WeightAppx ageFloor areaAir space

(kg)(months)(sq m)(cu m)

10031.510.0

15053.012.5

22073.515.0

Source: ADAS.


Cattle most

at risk

&#8226 Dairy-bred animals – young bulls, steers and replacement heifers.

Pneumonia normally occurs in these animals in two seasonal peaks:

Early winter: Most cases occur at this time. Autumn-born calves 3-4 months of age are most susceptible because adverse weather coincides with when the animals colostral immunity has declined and its own immunity is not fully developed.

Early spring: Spring-born calves at an early age (often below three months of age) are often affected in February and March. These animals can have low colostral immunity, which, when combined with bad weather, can cause problems.

&#8226 Suckler calves

In common with dairy cattle there are two main risk periods in suckler calves:

Autumn/early winter: The autumn peak in pneumonia cases occur in 6-8-month-old spring-born and summer-born calves and is associated with weaning and housing. There will also be the extra stress of marketing. Early-autumn-born calves of 3-4 months of age that are suckling their dams may also be affected because of bad weather.

Mid-winter: Fewer cases occur in mid-winter but late-autumn-born calves of about three months of age can be affected even though they are not weaned.


Viruses

&#8226 IBR (infectious bovine rhinotracheitis).

&#8226 P13 (parainfluenza).

&#8226 RSV (respiratory syncytial virus).

&#8226 BVD (bovine viral diarrhoea).

Bacteria

&#8226 Pasteurella.

&#8226 Haemophilus.


&#8226 Ensure calves have adequate colostrum.

&#8226 Castrate and dehorn as soon as possible.

&#8226 Avoid stress, such as changes in feeds.

&#8226 Ensure adequate ventilation and airspace, without draughts.

&#8226 Provide plenty of bedding.

&#8226 Ensure animals of different ages have separate airspace.

&#8226 Isolate sick animals.

&#8226 Keep stocking density low.

&#8226 Vaccinate when the pneumonia bug can be identified.

Mervyn Davies, ADAS stock research team manager (right), with ADASconsultant, Harry Grundy, at Rosemaunds veal demonstration unit.