A foal whose birth was watched by hundreds of people on a webcam died minutes later.
The birth was filmed as part of a community farming initiative, MyFarm, run at the National Trust's Wimpole Home Farm in Cambridgeshire.
A trust spokesman said: "The foal had a perceptible heartbeat when born but was not breathing.
"None of our efforts could save her and she peacefully slipped away a few minutes after her birth."
The farm's only shire horse mare, Queenie, was the first large animal to give birth since the National Trust started the MyFarm initiative in May.
The project aims to reconnect people with farming methods, where their food comes from and how it is produced.
For a small subscription, "virtual farmers" are able to help make decisions about how the farm is run and which crops are sown.
The National Trust said the decision to show the shire horse birth on a webcam was "a huge one" as Queenie had previously miscarried, and another of her foals had to be put down after it was born with a deformity.
Farm manager Richard Morris and horse manager Emma Warner were both present throughout the labour and a veterinary surgeon advised the team by telephone.
Mr Morris said: "As you can imagine, we are all devastated by this awful and unexpected outcome.
"Although watchers of the foaling on the webcam saw the true, grim realities of animal husbandry, this in no way belittles the personal sense of tragedy and loss we are all feeling.
"This bitter disappointment is tempered only with the fact that the filly foal did not suffer at all."
"Farmers" who watched the birth on the webcam have posted condolence messages on the website's discussion pages praising the efforts made by staff to try to revive the foal.