Group One-winning jockey Rachel King has undergone surgery on her collarbone after being injured in a fall at Tamworth.

King was one of three of the five riders involved in Sunday's incident to need an operation.

Her boyfriend, fellow jockey Blake Spriggs, said on Twitter on Monday evening the surgery had gone well.

"I just spoke with @RachelK11 's surgeon and he is very happy with how the operation went. Rachel is now in recovery and I expect to speak with her soon. I want to thank everyone for their messages of support." Spriggs said.

Greg Ryan's mount Son Of A Dun appeared to go amiss midway through Sunday's 1400m-race with four horses then suffering interference.

Ryan suffered a mild concussion in the incident was discharged from Tamworth Hospital on Sunday night.

The Australian Jockeys' Association said Josh Adams had lower lumber spine fractures that appeared stable but he may need to be transferred to Newcastle.

Adams also has a fractured femur which will require surgery.

Apprentice Wendy Peel will go to Sydney for surgery on a broken shoulder while Kath Bell-Pitomac has concussion and suspected broken ribs and will remain in hospital for a couple of days.

King, who rides comfortably at 51kg, won the Spring Champion Stakes on the Mark Newnham-trained Maid Of Heaven and rode Godolphin horse Encryption to seventh in Saturday's Newmarket Handicap at Flemington.