Screening sperm for dairy herds is a billion-dollar industry, but a New Zealand company has shed light on a new way to choose a bull or a cow.
Kiwi start-up Engender has just won a Silicon Valley hi-tech award for a process that uses lasers for sex selection.
Lasers can do amazing things, like write a word on a single strand of hair.
But at Auckland University's Photon Lab, they're being used to screen bull sperm.
"Right now the current technology damages the sperm so there is a lot of reduction in viability and it's quite expensive," says Dr Cather Simpson from Engender Technologies.
Engender's technology allows bull sperm to travel unbruised in tiny tubes, where the force from a laser light gently pushes the cells into swimming the same way so they can be tagged.
"So we stain the cells and the X-chromosome is a bit bigger than the Y, so the females are a bit brighter than the males," Dr Simpson says.
Another laser then sorts the males and females by nudging the bigger females away into a tube.
The process scored a Silicon Valley World Cup Tech Challenge award and possible investors.
"When I came off the stage after giving my pitch there was someone from an Asian company standing there with his card," Dr Simpson says.
"Before I could turn in my microphone [he said], 'We want to talk to about investing'."
The dairy industry uses 175 million straws of semen a year, at about $30 to $40 each.
Engender says it could produce a semen straw for $10.
"If you think about that at $10 a pop that's a lot of money," Dr Simpson says.
"[It's] about $1.5 billion just for dairy."
It's less cost and less wastage, not only of bull sperm, but also potentially bobby calves.
If each dairy herd was fertilised with high-quality sperm then the calves could be worth feeding, not killing.
Once they have sorted out bull sperm the Engender team is eyeing up Asia to sort out pig sperm, because female pigs pack on more weight and are tastier.
The technology can be applied throughout the animal kingdom, but there are currently no plans to apply their lasers to humans.