While the serious competition starts on Monday, hundreds of cows were moved into Tatura Park last week, and the entertainment started with a food truck day on Saturday and youth events on Sunday and Monday.
Tatura Park is hosting 736 head of cattle, entered in 928 sections, on Tuesday, Wednesday and Thursday.
The temperature reached just over 30ºC on Sunday, but the cattle were kept cool with water and fans.
The event is a major fundraiser for several service clubs and sporting groups that provide volunteers to deliver food and other services.
On Sunday, dozens of young people participated in a cow fitting challenge, the VASA state junior judging and parading competition and the Sherri Martin youth showmanship classes.
Monday will see the national youth show and the National Illawarra Show, while Tuesday, will see the Ayrshire, Guernsey and Brown Swiss shows.
On Wednesday, Jersey entrants will take centre stage, and on Thursday, Holsteins will compete in the ring of the Blackmore_Leslie complex.