'Chick sexers' are paid £40,000 a year to spend their days with tens of thousands of fluffy chicks.

But despite the seemingly attractive offer, Britain's poultry industry is struggling to recruit and is now facing a staff shortage that is threatening exports.

The problem, according to one industry chief, lies in the nature of the job: sexers spend 12 hours a day 'staring at the backside of a chick'.

And each new recruit must spend three years learning how to do it.

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Chicken sexers: Workers spot the 'minuscule differences' in the size and shape of each one-day-old chick's genitalia - known as its 'vent' - to determine whether it will be a rooster, or will one day lay eggs

Andrew Large, chief executive of the British Poultry Council, added that another part of the problem is that the awareness of the role is not as high as it could be.

Each future 'chick sexer' receives years in training in how to spot 'minuscule differences' in the size and shape of a newly-hatched chick's genitalia to determine whether it will be a rooster or a hen.

They are expected to be able to sort between 800 and 1,200 day-old old chicks an hour - between three and five seconds a chick - with an accuracy of 97 or 98 per cent.

This must be done for as long as it takes to fill an order, which can be up to 13 hours.

And each chick must have its genitalia - known as its 'vent' - checked without being harmed, Mr Large told The Times.

Delicate: Each chick must be handled with care

Although the checking technique can be taught relatively quickly, the ability to maintain standards for such long periods at such level of intensity has to be developed over a longer time.

In 2013 the industry failed to recruit a single 'vent chick sexer' and asked for the job to be added to an official government list of occupations with staff shortages.

Mr Large told The Times: 'It takes three years to train someone so they develop the sensitivity and dexterity to reliably sex the bird and a lot of people don't want to spend that amount of time training.

'I think the problem is the job itself. You are spending hours every day staring at the backside of a chick. That is not seen as being attractive.

'In southeast Asia a chick sexer is a high status job. In the UK it is more likely to be the butt of humour.'

There are an estimated 100 to 150 chick sexers in the country but a shortage of 15 workers means the industry risks losing overseas clients.

But the Migration Management Committee, who advises the government on whether a job should be added to the shortage list, ruled that chick sexing should not be included.

Chick sexing has previously made headlines as a number of the birds - mainly male - are discarded and killed if they are surplus to the requirement of the order.

When asked by MailOnline whether this could affect the number of jobseekers applying for jobs as chick sexers, Mr Large said it was not an issue that had been raised with them.

He added that it was only if the birds did not fit the order, and could not be redirected to meat production, that they were 'humanely culled'.