South Australian apprentice jockey Dylan Caboche has been suspended for two weeks after punching his mount She's Reneldasgirl before a race at Port Lincoln.

Footage of the incident shared on social media shows barrier attendants trying to get the fractious filly into the gates, with 22-year-old Caboche aboard, before he dismounts and punches her rib cage.

The three-year-old ($101), trained by Allan Jarvis, finished eighth in the 10-horse maiden over 1390 metres.

Thoroughbred Racing SA stewards announced the rider's suspension in a tweet on Wednesday afternoon.

"Dylan Caboche was suspended under rule AR175(q) (misconduct) for striking his mount prior to loading. Suspended from midnight 17/11/17 to 1/12/17," it reads.

She's Reneldasgirl was the first of Caboche's seven rides at Port Lincoln on Wednesday, with the apprentice winning the final race on Slide Of Hand.