Britain’s livestock producers have made remarkable progress in reducing their dependence on antimicrobials to control infectious disease – but are current practices sustainable and is there still scope for further improvement?
Speakers at the Responsible Use of Medicines in Agriculture (RUMA) conference in London on 29 October 2019 welcomed the latest figures on antimicrobial usage on farms but expressed concern that social and economic factors might threaten the progress made by the industry to limit the spread of resistant bacterial strains.
The meeting coincided with the release of the 2018 Veterinary Antimicrobial Resistance and Sales Survey data which showed a 53 percent reduction in total antibiotic sales last year compared with 2014 figures. There was also a two-thirds reduction in use of three classes of antibiotics considered critically important in human medicine, fluoroquinolones, third and fourth generation cephalosporins and colistin.
This meant that UK agriculture now has the fifth lowest level of antibiotic use in the EU and the lowest among those five countries with the biggest livestock industries. More importantly, the survey produced the first evidence of a reduction in isolations of multidrug resistance strains in animals, said Kitty Healey, head of antimicrobial resistance with the Veterinary Medicines Directorate.
This downward trajectory in the usage curve can continue but not at the same rapid rate. Catherine McLaughlin, vice-chair of the RUMA steering committee, believed that the initiative has harvested all the “low-hanging fruit” and any further gains are likely to be hard won. So far, the fastest reductions have been made in the intensive pig and poultry industries and the focus must now shift to the dairy, beef and lamb sectors where the production systems are more complex and less amenable to simple husbandry solutions.
Stuart Roberts, National Farmers Union vice-president, said that the strength of the RUMA initiative was its collaborative approach between farmers, vets, suppliers and food processors. He acknowledged that new legislation was an option to “sweep up” those remaining producers who were unwilling or unable to curtail their antibiotic usage. But he was sure that persuasion would offer more chance of success: “If you are doing something because someone tells you to, then you haven’t bought into the reasons why you should be doing it – you should realise that it is good for your business.”
However, developments in veterinary science that lead to new vaccine approaches to disease control can significantly reduce the need for traditional chemical treatments in controlling livestock diseases.
Julie Fitzpatrick, scientific director of the Moredun Research Institute, outlined developments by her colleagues that may reduce the risk of resistance arising against both antibiotic and anthelmintic drugs. A world-first vaccine against a nematode parasite has been developed by Scottish and Australian researchers for use against Haemonchus contortus in lambs. It is licensed for use in Australia and South Africa, countries where anthelmintic-resistant strains of the parasite had been endangering the future of the sheep industry.
The vaccine is produced by harvesting nematodes from the abomasa of lambs at slaughter and extracting a protein from the worm gut. When used to inoculate lambs, the vaccine significantly reduces egg output and with less pasture contamination the number of annual drench treatments can be cut from around eight to two – as regular treatment is still needed against other common gastrointestinal worms. However, the knowledge gained from this project is helping towards the development of further vaccines against parasites that are major problems in the northern hemisphere such as Teladorsagia (formerly Ostertagia) circumcincta, she said.
Perhaps the biggest barrier to reducing UK agriculture’s reliance on veterinary medicines is the threat of a no-deal Brexit, Mr Roberts warned. If reduced to working under World Trade Organization rules, the country’s farmers would be unable to compete against food imports from outside Europe produced using methods that would be illegal under British welfare and medicines legislation. He urged all stakeholders in the UK food industry to work together in persuading consumers of the need to buy produce reared in accordance with current welfare and environmental standards.
Several speakers stressed the importance of transparency in helping consumers to make appropriate choices. The notable success in containing antibiotic use on UK farms was a valuable tool to help retain the loyalty of UK consumers and develop new markets abroad. So, it was disappointing for the organisers that the meeting took place a few days after the news of an illegal consignment of amoxycillin being intercepted en route to a poultry unit in Northern Ireland. BVA senior vice president Simon Doherty felt the news undermined efforts to uphold the reputation of UK farming and was a “blow to the whole poultry sector”.
One audience member suggested that a way to ensure medicines are used responsibly would be to put all prescriptions under veterinary control. However, it was felt that this approach would be difficult under UK conditions and impossible in many countries abroad where there is a chronic shortage of veterinary manpower. A more realistic solution would be to provide training for non-veterinary support staff to give better guidance to producers in countries where there is massive overuse of antibiotics, suggested Shabbir Simjee of the RUMA independent scientific group.
