'They want love and affection. They need meat, not bread and milk,' he told a sympathetic audience at the Game Fair in Tabley Park, Cheshire.
Mr Ludlow, who farms 300 acres (120 hectares) in the Chilterns, was helping out at the stand of the National Ferret Welfare Society, a body which claims 900 members, some from Sweden and America, where ferrets have been raised for their fur.
He grew agitated at the thought of the cruelties inflicted on ferrets in the past, when they were kept in small cages, or had their canine teeth broken off to prevent them from settling down to a snack in the rabbit warrens.
'There's an answer to that now]' he cried, and produced a ferret detector from a cardboard box. It is a sort of modified baby alarm. The ferret wears a collar round its neck which contains a small radio transmitter powered by a hearing-aid battery.
The owner has a radio receiver tuned to the ferret frequency: if the animal vanishes underground, he just walks to where the signal is strongest, and then digs straight down until he finds it.
Mr Ludlow has kept ferrets himself for more than 20 years. At the moment, he has three of his own, and several more which had been rescued by the RSPCA after their owners abandoned them.
Mr Ludlow's ferrets are used for rabbit control: the technique has not changed since the Romans brought ferrets to this country to help manage the rabbits they had themselves introduced. The rabbit is chased into a purse net, where it traps itself until killed.
'How long', Mr Ludlow asked, 'is the hair on the back of a wild rabbit?' Various people gave their best guesses. 'No]' he replied: 'about four seconds, until it realises its mistake and apologises - ha ha ha ha. I told you ferreters had more fun than people who practise the other country sports.'