Ideal for lifestyle blocks and small farms, the bales were easy to handle and feed out, with no need for a tractor, they said.
The couple, who already operate a lucerne chaff business, were visiting Mrs Purvis's parents in West Sussex when they first got the idea, having seen mini-bales of haylage produced on the neighbouring property.
They did some research, visited feed stores and decided it was something they could do on their own 40ha property.
They had the contacts to sell it and saw it as complementary to their chaff business, and so they imported a wrapping machine and bale grabber from the United Kingdom.
The couple have heeded a comment made by the neighbour of Mrs Purvis' parents, who said it was imperative to make a top-quality product.
"You put quality feed in and you get quality feed out," Mr Purvis said.
They only cut about 1.2ha at a time as the bales need to be wrapped within two to four hours of baling.
High-density bales were produced - each weighing between 30kg and 40kg - and eight layers of highly tensioned wrap were used.
A lot of wrappers were stationary and required the bales to be carted before being wrapped, whereas the Purvises' wrapper was mobile, enabling bales to be wrapped in the paddock.
The couple said there was no waste, as the baylage was more palatable and had better feed value than meadow hay, and horses, cattle, sheep and alpacas "love it".
During the very dry period earlier this year, they fed their calves on the mini-bales and they did very well, they said.