The stud was started in 1957 and began using artificial insemination in the 1970s to advance its genetics faster.
The business has 250 registered Hereford cows and sells 75 bulls and more than 50 registered females each year.
"That was an awesome experience. One of their bulls was named supreme champion Hereford at a national stock show," she said.
"I've made a number of connections in Montana and I'd like to return to the state to work and grow my knowledge one day."
Calder plans to study a Diploma in Agriculture at Lincoln University.
The five other students on the exchange were Sarah Humphries from Southland, Olivia Mackenzie from Ashburton, Rhiannon Simpson from Timaru, Tyla Bishop from Oamaru and Mikayla McClennan from Te Awamutu.