31 July 1998 Million dollar savings possible with commercially viable foot rot testing

A $20 million annual saving to the sheep industry could be delivered by Lincoln University's genetic marker approach to the age-old problem of foot rot.

Biochemist Dr Jon Hickford's grant in the latest round of Public Good Science Fund allocations ($100,000 per year for two years) means he will be able to continue working towards a commercially viable testing procedure which will allow breeders to select sheep that have an effective immune response to foot rot.

Currently foot rot is estimated to cost farmers $80 million a year in lost production. That's $4 a lamb on problem farms.

"If we can alleviate the problem, even by 25 percent, that's a saving of $20 million a year," says Dr Hickford, of Lincoln University's Animal and Food Sciences Division.

Dr Hickford is confident that within the next few years farmers will be able to assess natural resistance to foot rot by a simple blood test.

The gene has been identified and the challenge now is to improve the technology and lessen the cost.

"It is costing around $200 a head at present to 'type' animals," he says, "but our aim is to commercialise the test at around $20 a head by the year 2000."

At $20 a head Dr Hickford hopes the test will appeal to stud sheep breeders who can pass on the benefits of improved natural resistance to commercial sheep farmers through ram sales.

Foot rot is one of the most economically damaging diseases affecting the sheep and goat industries in temperate climates that enjoy good rainfall. The disease is caused by a highly contagious bacterium Dichelobacter nodosus. The bacterium invades the area where hoof and tissue join and degrades proteins thus causing lesions or ‘rot’.

At Lincoln University Dr Hickford and his team have been investigating sustainable ways of controlling foot rot which will lessen farmers' dependence on chemical treatment alone. Identifying a gene responsible for natural resistance has been the approach. Many of the traditional chemical/antibiotic approaches are disfavoured either because unacceptable substances have been found to be passed on residually to food products derived from the treated animals, or they involve the use of hazardous chemicals or they are expensive.

Making use of the long-known fact that many sheep display a ‘natural resistance’ to foot rot, Dr Hickford and his team set about identifying the gene responsible for this.

Selection for resistance to foot rot has a 0.3-0.4 heritability factor, says Dr Hickford. It is possible to see a difference in one year of selection and it is equal to factors like wool weight or growth heritability, he says.

Dr Hickford is working closely with four farmers who have been deliberately selecting for foot rot resistance for many years.

The research is very ‘on farm’, he says and he praises the work and cooperation of Edward Orr, Rodney Patterson, Angela and Jamie Molloy, Brian Dickson, also the Corriedale Breed Society and Mohair New Zealand Inc.

Edward Orr, a Senior Vice-President of the Meat and Wool Section of Federated Farmers, is a key person in the work, says Dr Hickford. He has a foot rot resistant flock of Corriedales and is a great ally in the research. Rodney Patterson is a key person too, in the Merino area.

Dr Hickford stresses that his work is not aimed at finding a ‘cure’ for foot rot, but says that by improving an animal's natural resistance to the problem it should be possible to reduce the severity of the disease, its economic impact and allow better management of serious or recurring problems.

Ian Collins, Journalist, Lincoln University, Canterbury, New Zealand