A couple who sold "shares" in their cows to supply unpasteurised milk are on trial in Adelaide for breaching food standards.

Prosecutor David White said Mark and Helen Tyler from Willunga Hill, south of Adelaide, operate what is known as a "house cow share scheme" for about 30 milking cows, ABC News reports

They offer shares to the public for about $30 each, which allows people to take home bottles of unpasteurised milk, also known as raw milk, after paying an additional "boarding fee".

White said the Government did not allow the sale of unpasteurised milk under the Food Act because of public health concerns.

It is, however, legal to drink unpasteurised milk from your own cow.

Mr Tyler brought a cow to the Christies Beach Magistrates Court to show people what they were buying when they bought shares.

He argued they were buying into a cow rather than purchasing milk.

The trial heard evidence from Lance Holberton, who helped carry out an investigation for Primary Industries and Resources South Australia (PIRSA).

He purchased a share in a cow and collected some milk after paying his boarding fee.

His interaction is the subject of the first charge against the Tylers – selling milk that did not comply with the Australia and New Zealand Food Standards Code (ANZFSC).

Another PIRSA official is due to give evidence during the trial that he took samples of the milk from the dairy in August 2013.

The samples were tested and showed microbiological contents well in excess of allowable levels under food standards.

That evidence is the subject of a second charge: failing to comply with a requirement of the ANZFSC.

The trial is listed to run for three days.