Picnickers using Berkshire's countryside and commons are being urged not to feed grazing animals that can become ill and reliant on human food.
Exmoor ponies are among the animals at risk
West Berkshire's countryside and trading standards officers have united to urge people having picnics to act responsibly and take their food home.
Among the concerns are fears that meat scraps will cause disease among grazing cattle or Exmoor ponies.
Processed foods for human consumption can also make the animals very ill.
Sarah Langley, lead officer for animal health and welfare said: "Any leftovers containing meat or meat products left on the commons could be eaten by the cattle or other farm animals who graze on them.
"These can cause disease and could ultimately lead to the loss of the animals.
"It is for this reason that it is illegal.
"We have put signs up around the commons to remind the public to take their food waste home with them and we would be grateful for their support."
Paul Hendry, countryside manager, said the risk of disease was not the only problem.
He said: "The public should not feed any titbits to the animals as it encourages them to approach people, which not everyone wants, and the animals can become a nuisance and too reliant on humans for food.
"Also, some of the animals have newborns at the moment and they can become distressed if approached by the public, especially if people are walking their dogs."