3 Day Sickness ( BEF)
Introduction
Bovine ephemeral fever (BEF) is an important disease in dairy cattle because it is most severe in the more valuable classes of cattle such as bulls, pregnant and lactating cows, and fat, well-conditioned cattle. Additionally, the disease spreads readily to infect many animals in the herd.
A vaccination program can produce long-term immunity and is integral in minimising the effects of disease caused by BEF in a dairy herd.
Cause
A virus, which is spread by insects. (BEF is not transmissible to humans).
Symptoms
- fever, stiffness, lameness, loss of appetite, excessive thirst, and recumbency;
- may cause heavily pregnant cows to abort;
- prolonged recumbency may result in animals requiring euthanasia; and
- death can occur in severe cases of BEF infection.
Animal welfare
Animal welfare is a major concern and more recently, a consumers' demand. One of the main measures of welfare is freedom from disease. A vaccination program can significantly reduce the incidence of disease.
Potential risks
BEF presents a significant risk to dairy herds due to the following factors:
- The disease spreads rapidly through herd.
- Animals lose immunity during low rainfall periods and become susceptible.
- Often a sporadic disease with outbreaks occurring every couple of years especially after drought-breaking rain.
- Usually more severe in bulls, fat, well-conditioned cows and pregnant and lactating cows.
- Outbreaks depend on rainfall and warm temperatures, which increase insect populations.
- Waves of disease occur with increases in insect populations, from north Queensland towards the south in January and February.
Incidence
- ARI reported 40 dairy herds infected in Queensland from 1996 to 2001
- DPI reported extensive numbers of cases in cattle in south-east Queensland from October 1999 to June 2002
Potential economic losses
Significant economic losses can occur because the disease is most severe in the more valuable classes of cattle: bulls, pregnant and lactating cows; and fat, well-conditioned cattle.
Signs usually last only a few days but the disease can significantly affect the herd's production in the following ways:
- a dramatic drop in milk production - over 70 per cent is not uncommon
- milk yield after recovery is often reduced by 15 per cent or more;
- lactating cows can dry up completely;
- abortion can occur in heavily pregnant cows;
- occasional deaths (three per cent) or prolonged recumbency leading to 'downer syndrome' can occur;
- most of the herd can be affected ; and
- bulls may be temporarily infertile.
An example of the potential cost of an outbreak:
- with 15 per cent milk loss and with milk being worth $0.29 per litre; and
- three per cent death rate and cattle being worth $1 000/head;
- the loss over one month in a 100-cow herd would be $5 700.
The cost of treatment for affected animals can also be considerable.
Prevention and control
Vaccination program:
- give the first dose at six months of age (preferably in September or October);
- a second dose of vaccine is required two.four weeks later; and then
- give an annual booster eight - ten weeks before the BEF season.
Vaccination costs
It is important to compare prices of the various retailers to ensure implementing the most economic vaccination program.
Vaccine costs for BEF:
Vaccine costs in this article indicate the cost of the dose only and do not include labour, materials or facility costs.
- $1.70 per dose approx.;
- if the herd includes 100 cows, 3 bulls, 25 heifers, 40 heifer calves (calves require two doses) ® 208 doses/year @ $1.70/dose= $355.00/year.
Therefore, if an average cow were valued at $1 000, the program would break even if the equivalent value of only one animal were saved every three years by vaccination.
Important considerations when vaccinating cattle:
- The manufacturer's instructions should be followed closely.
- It is important to store and handle vaccines correctly to ensure their effectiveness is not reduced.
- Safety precautions for workers handling vaccines and associated equipment should be adhered to carefully.
- Ensure safe disposal of used equipment, avoiding environmental contamination.
- Animals should be in good health to optimise the immunity gained - the immune response may be poor in severely undernourished animals or cattle that are stressed by other diseases.
- Vaccination does not provide instant protection - generally full protection doesn't occur until up to four weeks after the initial doses.
A vaccination program can be a very cost-effective management tool in avoiding the potentially high production losses due to BEF in a dairy herd.
For more information on this project, please contact:
Lex Turner
Agency for Food and Fibre Sciences
Department of Primary Industries
MS 825
MUTDAPILLY Q 4306
Tel. 07 5467 2100
Fax. 07 5467 2124
email lex.turner@dpi.qld.gov.au
Visit www.dpi.qld.gov.au/dairy
© The State of Queensland, Department of Primary Industries, 2003