Concern groups are enlisting the help of hikers to find and report on cattle moved from their traditional roaming grounds by the government.
The groups claim some of the cattle are struggling to adapt to their new environments after being moved in a bid to reduce nuisance to local residents.
The Friends of Mui Wo Cattle and the Association for Tai O Environment and Development say the animals' health has worsened and want hikers to report to them if they see cattle wandering the countryside.
At the centre of the controversy was the Agriculture, Fisheries and Conservation Department's move in November to relocate 29 of the wandering cows and bulls in Sai Kung to Shek Pik, southern Lantau, and 21 of those wandering around on Lantau to High Island, Sai Kung.
Seeman Ho, chairwoman of the Friends of Mui Wo Cattle, criticised the department for failing to consult the group in advance.
"We have been kept in the dark until recently when some of our members learned from friends that some oxen originally on Lantau were seen in Sai Kung," she said.
Ho Pui-han, of the Association for Tai O Environment and Development, said the department was, in effect, torturing the animals.
"Those sent to High Island do not have enough grass to eat. And there are no trees for the cows to shelter under during bright, hot days," she said.
The groups urged the department to move the cows back to their original homes.
A department spokesman said yesterday that the exercise aimed to prevent disruption to traffic and nuisance to local residents from the presence of so many roaming cattle.
The department numbered each of the animals so it could trace where they went and check their health.
Feral cattle have been a point of contention among residents for years. They are regarded by some as a nuisance and by others as a part of the community.
There are thought to be about 1,200 feral cattle on Lantau and in the New Territories.
Last June, eight were killed in a hit-and-run on Lantau.