Smith's counsel James Rapley said his client accepted that the offending was serious and he was ashamed of his actions.
"He hadn't realised it had been that bad," Mr Rapley said.
A veterinary inspection of the herd was arranged in late April and found that 154 cows had a total of 172 fractures in their tails that were clearly deliberate.
Mr Rapley said it was not a case of extreme violence, as it had been in some recent, similar cases. He said the tails were broken when the cows were being moved. He said it was common for farmers to try and move cows by grabbing their tails and pushing them. But breaking the tails required a force equivalent to lifting a two litre bottle of milk on the end of a metre-long broom stick. The pain inflicted was comparable to a person breaking a finger.
Prosecutor Grant Fletcher said a lengthy ban would have sent a strong message to those in the agricultural industry. He said it would act as a massive deterrent.
Judge McMeeken said the purpose of the Animal Welfare Act was to set standards in relation to the care of animals. In relation to cows, the Act said minimal force could be used when moving cows. But in Smith's case the force was not minimal.
"I accept that you are genuinely remorseful and in fact you are horrified by what you have done," Judge McMeeken said.
"Mr Smith you are a family man. I accept that you have learned from this and that you accept that your behaviour was totally unacceptable."
From a starting point of two and a half years in prison, she sentenced him to eight months' home detention and disqualified him from owning animals, with no minimum time frame. If he wants to own animals in the future - other than companion animals - he will have to apply.
He was also ordered to pay vets' costs of $428.
She said had home detention not been available, Smith would have gone to prison.
Smith has since moved away from Ashburton and had started a new job, not in the dairy industry.
