Katie Milne said the stupidity of the shooting on her Rotomanu farm near Lake Brunner had left her speechless.
''Our calf was shot yesterday at 3.15am in a paddock with a prominent 'no shooting' sign in it. I presume a poacher mistook our calf for a deer, but who really knows?'' she said.
The calf was left with a gaping wound to its right shoulder and had to be put down.
Milne has been unable to identify the poachers, and the incident has left Federated Farmers concerned that someone will end up being killed.
She said poaching was illegal and dangerous.
''Our calf, which was on private property, was shot from a vehicle less than 60 metres from a public road.''
Milne is the federation's rural security spokeswoman and said she would never grant hunting permission to a stranger because of the potential for a deadly shooting incident.
A freight truck is understood to have disturbed the poachers before they could do more damage.
A neighbour saw hunters with spotlights between houses earlier that night.
Federated Farmers is working with police on rural crime and farmers are being told to record the licence plates of strangers.