Dairy farmers wanting to choose the sex of calves will have unrestricted access to the means of doing that for the first time this breeding season.
New reproductive technology that allows livestock semen to be sexed with a 90% success rate before it is distributed for artifical insemination has been available in the United States for some time.
New Zealand's use of it, however, has been limited because it required semen or breeding bulls to be sent to the US.
That changed last year, when the American company that owns the process set up a laboratory at the Waikato Innovation Park to supply sexed semen from New Zealand cattle.
The genetics manager of one of the livestock breeding companies using the service, Peter Gatley of LIC, says that happened well into the mating season, which meant that the supply was limited.
But he says there's no shortage now and trials and the use of sexed semen so far show that it does work.
Mr Gatley says dairy farmers may want to get more female calves in particular if they are expanding their herd, or if they want to get heifers calves from their best cows.