Why more efficient egg production requires vaccination rethink

Hitting the current 72-week average laying cycle in free-range egg production was once considered exceptional, but it is not uncommon now to see white bird flocks in-lay for 110 weeks.

This is good news for producers on many levels, more so now in a period when pullet supply is challenged.

For those pullets, vaccination is an important component of the in-rear phase, including live vaccines for salmonella.

See also: What to consider before extending layer life beyond 72 weeks

Since they were rolled out in the 1990s these vaccines, in combination with the UK national control programme, have been effective at controlling the bacteria in layers.

Pullets get three doses in-rear, a requirement of the Lion Code of Practice which is managed by the British Egg Industry Council (BEIC).

Those three doses provide immunity from Salmonella enterica for 68 weeks and Salmonella typhimurium for 62 weeks – two strains relevant to the national control programme.

As a consequence of that programme, the UK egg industry has an “enviable and exceptional” international reputation for its salmonella control, according to Gary Ford, head of strategy and producer engagement at the British Free Range Egg Producers Association (Bfrepa).

“Salmonella is a very low risk in this industry, but in the unfortunate circumstances that there is a positive, it is devastating for those involved,” he said during a recent Bfrepa webinar.

© Tim Scrivener

Changing industry

As the industry has made big advances in extending production cycles, it raises the question of what that means for salmonella controls, and should birds get a fourth dose in-lay.

The BEIC has been working with vaccine manufacturer Elanco and its in-house vet Josh Davison on developing best practice and guidance for using a new vaccine which can be given to birds at 50 weeks of age.

This protects them for another 50 weeks from Salmonella enterica, extending lifetime cover to 100 weeks. It also adds a further 44 weeks’ defence against Salmonella typhimurium, increasing protection to 94 weeks.

Vaccine conditions

The BEIC is not making it a mandatory requirement to use this vaccine in-lay.

Mike Tyers, the body’s technical adviser, said: “Salmonella control is the bedrock of the Lion code of practice, so we welcome this opportunity to have this extra vaccine, but it is not mandated – we are allowing it.”

As it is a prescription-only medicine, Mike is advising egg producers to work closely with their vet on best-practice requirements, but added: “It is not a free-for-all either. There are some conditions attached to it.”

What are those conditions, and how will the process work?

Age of birds 

The vaccine is regulated to administer to birds at 50 weeks of age. Josh said there was very little flexibility on that age requirement, although 49.5 weeks or 50.5 weeks would be acceptable.

Producers with an older flock who are considering using the vaccine would need to wait for their next flock cycle to use it in-lay, even if the birds are just 51 weeks old.

Withdrawal period and performance

If birds have had three doses in-rear and a fourth dose in-lay, there is a zero-day egg withdrawal period and so no loss of sales.

“As far as we are aware, the vaccine has minimal effect on the bird post-vaccination so it shouldn’t affect production,” said Josh.

Impact on routine swab testing 

Salmonella testing is part of a normal on-farm control programme and a key element of the Lion Code of Practice.

Josh advises against testing within a week of giving the vaccine. Instead he recommends either swabbing before vaccination or seven days after.

“For that zero-day egg withdrawal process, the vaccine has minimal shedding so it shouldn’t be a problem, but I think both recommendations would help with that,” he said.

“The product has minimal growth on an MSRV, the common agar plate used for detecting field versus vaccine strains, so that also should help provide a bit of confidence to users.”

Administering the vaccine 

As with salmonella vaccines given to pullets in-rear, the in-lay vaccine is administered through drinking water.

Producers need to be mindful that it is a live bacterial vaccine and therefore should follow all the correct procedures for handling and administering.

“It has to be treated carefully. Be aware of anything that can harm the bacteria,” said Josh. “It also has positive effects in how it confers immunity to the birds.”

A training programme on vaccine administration provided by Elanco includes a website guide and a field support team. The company is running “train the trainer” events too.

Josh suggested that producers who were interested in using the vaccine should start the process by having a conversation with their vet.

“We can help support with training, but it is really important that each producer is in concert with their vet – and whoever else they have those conversations with – as part of that discussion for individual farm use.”

If the dose is not correctly administered or received by the bird, the bird won’t get that fourth-dose effect.

However, Josh said the ambition was to get to a point where producers had the resources and confidence to administer the vaccine correctly. 

“In theory it is a simple process, but there are some key steps to getting right. In the worst-case scenario if they get it wrong, it is a waste of money and a waste of resource.

“With the support and training given, that situation should be avoided.”

Cost of vaccine 

One dose a bird is equivalent to a “lot less than the cost of an egg at the farmgate”, said Josh.

While vaccine cost was a factor, he cautioned that it was important for the industry to understand why it had been developed.

“If we take a step back from that investment, it is part of maximising human health, and for that wider industry reputation of which salmonella control is so important,” he explained.

“Salmonella control is a big topic; vaccination is a component of it, but we have to look at this [holistically] as part of all the other things being done on-farm to really manage that salmonella aspect.”

© Tim Scrivener

Producer viewpoint

Dave Hodson of Rosehill Poultry sees the in-lay vaccine as a “very positive move” for the egg industry.

“It keeps pace with the fact that when I came into the industry, flocks depleted at 72 weeks. Now we see white bird flocks going to 110,” he said.

Strong egg sales had been achieved through the “hard work” of everyone in the industry and that reputation needed to be safeguarded, Dave added.

“I think it [a fourth vaccine] keeps in line with the ethos of the British egg industry, the Lion Code, that we are doing everything we can – and more,” he said.

“There are certain situations that it really suits, and over the next few years I would imagine a large proportion of the industry will be doing it.”