There will be a gap in the supply of an enzootic abortion of ewes (EAE) vaccine during June to August due to a batch failure in the manufacturing process.
Ceva Animal Health, manufacturer of the vaccine Cevac Chlamydia, said the anticipated batch had "failed to meet the quality expected to be suitable for release".
This had "temporarily affected the ability to meet the demands of the UK sheep market within the main seasonal vaccination period for EAE".
The firm added that it 'deeply regrets' any inconvenience caused to sheep farmers during this period.
Roy Geary, regional director at Ceva Animal Health, said: "As a responsible provider, we are actively addressing these issues to minimise the impact on customers.
“The manufacturing of vaccines is a complex process that involves stringent quality control measures and adherence to regulatory guidelines.
“In collaboration with relevant stakeholders, we have implemented comprehensive contingency plans to optimise the manufacturing and distribution process.
"Our dedicated team is working closely with our partners to resolve the challenges and restore normal supply levels as soon as possible."
Ceva Animal Health said the vaccine challenge was being treated with the 'utmost urgency', with alternative options being explored to speed up the supply chain for future batches of the vaccine.
The company said it anticipated that the issue in supply would be resolved, with some stock potentially available later in the season.
However, for some farmers, the supply would "arrive too late for them to use".
"We encourage all farmers to consult their vet and explore alternative means of safeguarding the health of their flocks during this period," Mr Geary said.
"We recommend implementing robust biosecurity measures and adhering to existing vaccination protocols for other preventable diseases to ensure the overall wellbeing of livestock.
“We will provide vet practices and the wider industry with regular updates as we progress toward a resolution and return to normal supply levels.”
