Improved health has been the biggest gain from housing cows.
Aad van Leeuwen said there had been a massive decrease in cow lameness, which was now virtually non-existent, and mastitis, with just one case in the previous three weeks.
"It's 90%-95% down on what we experienced outdoors."
A key to that was maintaining a high level of hygiene.
As each cow is milked, the computer collects information such as milk volume, fat and protein levels, somatic cell count, mastitis, time taken to milk out and other health indicators. The somatic cell count in milk was about 65,000, compared to 250,000-300,000 in a conventional farm.
The collar each cow wears includes a pedometer which, with information collected by the computer such as milk temperature, can alert when it is coming into season. It also records how many times the cow chews its cud, an indication of how well its body is operating.
His animal health bill was $2000, and that of a a comparable sized conventional farm was $10,000, he said.
Should a major fault occur at night, the manager was alerted by telephone. Typically he would be called out if the cups were tangled or a hose coupling faulty.
Mr van Leeuwen has opened his farm to groups, including traditional critics of the system such as animal welfare activists and the Green Party, in a move to educate the public.