But there is a competition of a different type for humans, as the town’s Apple Pie bakery hosts a pie-eating contest.
“It is 10 years since they started, and they wanted to do something to celebrate being in business for so long,” said show secretary Anne Robertson.
Tickets for that will be available from the Biggar Road bakery, priced at £10, and the winner will receive £50, with all proceeds being donated to the Royal Hospital for Sick Children in Edinburgh.
The show again features sheep, cattle, poultry, rabbits, and horses, both Clydesdale and light horses, and entries are coming in steadily, but many farmers wait until the day itself.
Judging in the showfield, at Heads Inn Farm, begins at 9am, with the horse and pony classes, and the champion of champions should be picked at 1.30pm, ready for the parade of winners to take place at 2pm.
“There are also trade stands, and the craft tent is looking quite busy with different exhibitors,” said Anne.
There is also a pet and dog show, with entries taken on the field, and that starts at 11am.
The show also hosts the Carnwath Red Hose Race, the oldest foot race in the world.
It dates back to 1508, when James IV granted the lands of Carnwath to John Somerville on condition that he should pay “one pair of hose containing half an all of English cloth” at midsummer each year to the man “running most quickly from the east end of Carnwath to the cross”.
That has been extended to include women now, and one has already carried off the historic red hose.
There are cash prizes for winners, but the main prize of a pair of red socks can be awarded only to a local runner from the parishes of Auchengray, Braehead, Carnwath, Carstairs, Covington, Dunsyre, Dolphinton, Elsrickle, Forth, Libberton, Quothquan, Thankerton or Walston.
Entries for the 4.5km race are taken on the field from 11am, with the runners setting out at noon.
The race nearly ended in 2011 because of a lack of interest, but the announcement that it was being cancelled led to protests and that was when Carnwath Agricultural Society, the organiser of the show, took it on in association with Lee and Carnwath Estate.
Now runners head for Greenaton Farm and back, and there is a shorter route for children.
Numbers have been growing. Last year, there were 27 from all over Scotland, but the show organisers would like to see more taking part.
“We are trying to push it a lot more this year,” said Anne.
“Runners don’t have to live in the parishes to take part.”
Those attending the show are encouraged to cheer the runners back in and enjoy the spectacle.
Other attractions include dog agility and a sheaf-tossing competition.
“It is a good day out, and a good family day, with lots to see and do,” said Anne.
The fun continues in the evening with a speed-shear competition at 8pm, although organisers warn that that might not be suitable for younger children, and the show dance at 9pm rounds off the night.
Admission is £6 for adults, and £4 for pensioners and children.