The 17-year-old from Katamatite was named Champion Young Parader at the Royal Adelaide Show this month.
Sienna is a first-generation dairy farmer growing up milking cows, rearing calves and driving tractors.
She was runner-up in the paraders’ competition last year and hopes to one day become a qualified embryo technician.
“I’m pretty stoked; not many words I can say, to be honest,” Sienna said.
“My family definitely are the main reason I have such a love for showing dairy.
“I have Dad’s love of cows, Mum’s support and her determination for me to succeed, my brother’s skills building all my new gear, and my sister by my side at all the shows to learn new things.
“I grew up on a dairy farm and started with American cattle with my family, which we run together.”
The championships are held in a different part of Australia each year.
Agricultural Shows Australia chair Jacqueline Wilson-Smith said the event showcased agricultural excellence, boosted the industry and shone a light on outstanding achievements.
“These young competitors are the future of agricultural show competitions, which are so important to the growth of Australia’s food and fibre industries,” Ms Wilson-Smith said.
“The nationals are a fantastic opportunity for them to develop their skills, gain valuable experience and go head-to-head with the best in the country.”