"It's good for people to see what these dogs are capable of under situations like that, they're not savages or anything like that, they can be firm without being rough."
Eight-year-old Chief "is a real firm dog" so he began training at six months old before he could be taken to work with Peacock.
"He was really early, normally you wouldn't have a dog in a pressure situation 'til they're well over 12 months old, he was just really early maturing."
Chief is a former New Zealand short head champion, winning in 2018 and coming second in 2019 in sheep trials and represented New Zealand twice.
This year Peacock is captain of the 2021 New Zealand Sheep Dog Trial Trans-Tasman Test Team with his other dog Slim.
Training each dog is different, some can start at 3 months old and others 12 months old, and the trainer needs to work out when the dog is ready to progress and how much pressure it can take, Peacock said.
He starts the dogs out training with 10 to a dozen sheep in a flat paddock when they are young so he can work out what the dog is like and how he will go about training them.
"The crucial thing is to have the training sheep that are not challenging your dog all the time initially, so that's why I had to take that sheep [in the video] out because it wasn't going to be good for training a young dog."