Arnie grew up in Voluntown, Connecticut, where he was involved in 4-H, showing dairy cattle. He attended and graduated from Griswold High School and later the University of Connecticut. Arnie later became the manager of the university dairy herd in 1989. During his time at UConn, the first clones were born from the mature cell of a dairy cow. He was also one of the three recipients of the 1994 University Leadership and Achievement Award. At the University level, only three of these achievement awards are given each year. Additionally, while working at UConn, Arnie was the co-chair for the New England Holstein Convention, held at UConn in 1998. This was the ninth largest sale in the country that year.At the time of his retirement from UConn, the dairy herd was ranked top 5 university herds in the country.

Arnie has been a longtime supporter of 4-H, running his own club, Lebanon 4-H Beef & Dairy, for the last 50 plus years. His club is responsible for running the beef and dairy show, being gate publicity and running the horse and oxen pulls at the local 4-H fair, with the help from parents. Additionally, he has been the chair for the annual 4-H Plant Auction for over 30 years. Arnie ran the New London County 4-H Fair Association from 1983 through 1985. In 1984, during his time running the county 4-H Fair Association, he became part of the CT State 4-H Dairy Committee. Through his involvement on the 4-H Dairy Committee, he went to the Big E as a chaperone for over 22 years, later becoming the Superintendent of the New England 4-H Dairy program at Eastern States in 1991. Arnie was in charge of arranging the 4-H Dairy show from start to finish, during his time as 4-H Dairy Superintendent, through 1998.In 1991, he started a sponsorship program for the New England 4-H Dairy Program, to supplement the number of awards offered each year. Prior to becoming 4-H Dairy Superintendent, Arnie was chairman for the committee for three years. Arnie, has received not one but two citations from the state legislature for his 4-H work in the state, one in 1988 and the other in 2019. He also received the 4-H Leadership Award for CT in 1988. Most recently, Arnie was nominated for the 2021 National 4-H Hall of Fame from Connecticut.

Arnie has also been a staple breeder, exhibitor and supporter of the New England Dairy Industry for many years. He served as a director for the New England Holstein Association, as President for the CT Holstein Association and was on the planning committee for the 2005 National Holstein Convention Committee. The convention was held in Portland Maine that year, and was the second largest Holstein Convention ever held. In 1985, Arnie was the Chair of the New England Junior Holstein Tour in Connecticut. In 2003, he became the Dairy Superintendent at The Big E, along with co-superintendent Bonnie Burr. In addition to being Dairy Superintendent, Arnie helps secure award donations for the Junior and Open Holstein shows at Eastern States each fall. Additionally, Arnie served as Dairy and Beef Superintendent at Brooklyn Fair for 18 years and at Lebanon Fair for over 32 years. Arnie is currently still the beef and dairy superintendent at Lebanon Fair today.

Over the years, Arnie has been a longtime exhibitor at Eastern States. His children, Kristen Nieminen Tarryk and Kurt Neiminen, as well as grandchildren Donald Jr, Zach and Jacob Tarryk, have continued exhibit at The Big E for many years.