A Suffolk Punch foal is the first in the UK to have been born using technology to determine its sex.
The filly, born in Whitchurch in Shropshire, was conceived using sex-sorted sperm.
There are fewer than 72 female Suffolk Punches remaining in the UK and fewer than 300 in the world.
The new method could be used to save the breed, which has been described as “rarer than the panda”, from extinction.
The technology makes it possible to select female foals to increase the breeding population more quickly.
Tullis Matson, owner and managing director of Stallion AI Services where the foal was born. said it was “fantastic news” for all rare breeds.
“Last year, I think there were about 35 born, 19 were male and 14 female, so it always tends to be more gender male heavy and we need more females on the ground so they can breed more,” he said.
“These are the horses that ploughed our fields during the war, they are the ones that put food on the table.
“For me we have got to keep our heritage going and so we’ve got to find a way of getting more females on the ground. There is a glimmer of hope at the end for them, there really is.”
Christopher Price, chief executive of the Rare Breed Survival Trust, said: “This is tremendous news for anyone concerned with the conservation of our native equines.”
Dr Gareth Starbuck, head of animal and equine sciences at Nottingham Trent University, which owns the mare that gave birth to the foal, added: “The birth of this foal marks a major step towards securing the future of the Suffolk horse and all other rare animal breeds.”