19 October 2001

Pneumonia vaccine proves worth

Calf vaccination against

pneumonia has reduced

mortality, labour and vet

costs on one Surrey dairy

and beef unit.

Hannah Velten reports

CALF pneumonia had never been a problem at Bregsells Farm, Dorking, until the calf rearing enterprise expanded and the coughing began.

Daniel Laker was rearing 20-40 replacement dairy heifers, but in 1998 he decided to rear up to 200 calves, including dairy bulls for intensive finishing. During that November and December, when calves were weaned off milk, they became ill and went off their feed.

All calves were quickly treated with antibiotics and although 95% appeared to shrug off illness, the rest did not perform well and 29 died later.

"It was depressing to see animals fit and healthy one day then coughing and losing condition rapidly the next. The costs and labour involved in treating animals did not cure the problem, as some had chronic lung damage which they never recovered from," he says.

Independent vet consultant Tony Andrews says an outbreak of calf pneumonia costs £43 a diseased dairy calf and £82 a diseased suckler calf. About 40% of costs are for vets and medicine, while the rest includes mortality and invisible costs, such as weight loss and labour.

Reduced weight gain was a particular concern in intensively reared bull calves at Bregsells Farm, as they had to finish within 14 months. Other calves destined for the two-year extensive beef system could still reach finishing weights, despite growth checks, adds Mr Laker.

After another outbreak of pneumonia the next winter, in which dairy heifer calves went down within seven days of birth, vet Rob Drysdale intervened and took blood samples. These showed respiratory syncytial virus (RSV) and infectious bovine rhinotracheitis (IBR) to be the cause.

Georgia Owen, Pfizer Animal Healths vet, says RSV is the most common virus causing pneumonia. "About 75% of 900 problem herds we surveyed showed exposure to RSV. When it gets on-farm, the virus causes high mortality. The source of calf infection is usually adult cattle which show no signs of disease but are virus carriers.

"IBR also remains latent in carrier animals, even in a closed herd, until cattle are stressed and start to shed virus, which can infect calves," she adds.

Mr Laker has a suspicion that both viruses could have entered the herd via bought-in animals and struck calves when calf stocking densities in housing increased.

After discussions with Mr Drysdale, Mr Laker decided to vaccinate calves in time for last winter. Because IBR had hit dairy heifers so early, all calves received an IBR intra-nasal vaccine at seven days old and a further two doses. A two-dose RSV vaccine was also used.

The vaccination programme proved timely, as the winter was extremely wet and damp. There was an outbreak of coughing, but they responded quickly to treatment with no obvious ill effects, says Mr Drysdale. "We did panic that vaccination had not worked, even though it had."

Coughing was caused by Mycoplasma bovis, a bug which suppresses calf immunity and makes them more vulnerable to viruses.

"Cattle of mixed ages were in sheds, sharing the same air space, and buildings were overcrowded. Vaccination does not prevent cattle from getting disease, it is only part of disease control, so producers must also take account of housing, ventilation and separating age groups," warns Mr Drysdale.

To solve this problem, Mr Laker is demolishing old calf housing and erecting new buildings for this winter. This will improve calf management and their environment, reducing the risk of disease spread.

Vaccination will be used again this winter. But replacement dairy heifer calves will receive a new vaccine, which covers RSV, IBR, PI3 and bovine viral diarrhoea (BVD) (Rispoval 4), plus the early IBR vaccine dose.

Only one calf died last winter and that was because she was infected by BVD, says Mr Drysdale. Adult cattle are vaccinated against BVD, so Mr Laker knew calves were at risk from the virus. "The new vaccine seems the sensible option to protect calves against all problem viruses on Bregsells Farm and it will reduce labour involved in vaccinating."

Ms Owen says BVD infection suppresses calves immunity, reducing their ability to fight off other viruses. "Our survey shows about 80% of 770 problem herds had antibodies to BVD and nearly 20% were exposed to all four viruses covered by the vaccine."

Calves will receive the four-in-one vaccine at three, six and 12 weeks. "Although data sheets recommend another dose at 15 weeks, we are experimenting and expect sufficient protection from three doses," says Mr Drysdale.

Mr Laker is unsure of the exact savings made by vaccinating calves. "Apart from reduced vet and med costs, vaccination costs were also covered by improved growth rates, no poor doers and a reduction in calf mortality." &#42

Vaccination against calf pneumonia has proved its worth at Bregsells Farm, say (l-r) Daniel Laker, Rob Drysdale and Georgia Owen.

PNEUMONIAVACCINATION

&#8226 Involve the vet.

&#8226 Can be cost-effective.

&#8226 Part of disease control.