''That's where you feed all your supplements on the concrete and then catch the nutrients.''
He said one of the main advantages was not having to run as many replacement young stock if cows were not in calf.
Over winter Mr Cotter's herd produces 1800 litres of milk each day, which is collected every second day.
Winter milking was something he hoped more farmers would consider doing in the future to boost supply to Fonterra's new mozzarella plant.
The new $240 million plant being developed at the Clandeboye site will cover about 9000sq m, making the factory 30% larger.
That growth will allow Clandeboye to double its mozzarella production.
Mr Cotter said more winter milkers would also mean an increase in fresh milk production.
''It's more cost-effective than bringing it down from Taranaki, which is where some of it came from last winter.''
Lyndsay and Alison Trounce, of Seadown, milk about 400 cows over winter.
Their son Andrew, who is also a farm consultant for Milkmap Consulting, said there were a range of benefits to winter milking, including cash flow.
At a time when some farmers were forking out for grazing costs, winter milkers continued to reap the rewards for the milk solids they produced.
For the Trounces, that was about 650kg per day over winter.
Like Mr Cotter, the Trounces have a stand-off pad so they can control effluent. Their herd also spends winter inside a barn.
Through his role as a farm consultant, Andrew was aware of about nine farms across Canterbury that milked over winter.
Fonterra was contacted for comment, but could not respond before Central Rural Life went to print.
