Wallawong, its clients Heath Birchall and Groveleigh Partnership, and St Mary's gained the three highest-scoring carcases out of 437 entries.

Between them, they exhibited 11 animals and took home the titles of Champion Heavyweight Led Steer, Champion Unled Steer, Supreme Champion Carcase (94.48pts), Champion Unled Carcase (94.48pts), Reserve Champion Unled Carcase (93.41pts), Champion Purebred Carcase (94.48pts), Heavyweight Jackpot Winner (94.48pts) and Overall Jackpot Winner.

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The 556kg Murray Grey steer that won both champion unled steer and champion purebred unled steer on the hoof was by Wallawong Yearbook who also sired the 2018 Upper Hunter Beef Bonanza supreme exhibit winning steer.

Another year book son weighing 558kg allowed Wallawong Premium Beef and Mr Birchall to also win the same title of heavyweight champion in the led section with their Murray Grey steer.

Wallawong co-owner and St Mary's agriculture teacher Lachlan James said the result was "impressive".

"The results are probably nearly unprecedented with such highly consistent carcases from one group of exhibitors and all in one competition," he said.

Mr James attended the beef bonanza with four students, Brad Miller, Saige Mitchell, Holly Miller and Charlotte Foody.

Year 10 student Saige came second in the 16 years junior judging out of more than 200 students.

"She's probably been competing and doing it for about two years but this would be by far her biggest achievement in that field," Mr James said.

Officiated by prime cattle judge Jake Phillips from Teys Australia, SA, the junior judging competition had participants look over and make judgements on a purebred heifer class, yearling Shorthorn bulls, and a class of steers.