Born in Verner, Northern Ontario, Demers was the third of a family of fifteen. His parents owned and operated a mixed farm, with milk production as a primary income source. After high school, he took the senior agriculture course at the Institut agricole d’Oka (Quebec), as no agricultural colleges in Ontario offered French courses at that time. He returned to Verner after his farm technology studies then raised poultry for a while. He further developed his agricultural knowledge and enrolled in the agricultural science degree program at Oka. He became an agronomist in 1962. The Ontario Ministry of Agriculture hired him as an assistant agronomist in the Prescott and Russell counties. Under the leadership of agronomists Laurent Farmer and Maurice Tessier, he took care of the 4-H movements and young farmers. His professional career reached a new level when he became a designated agronomist in Cochrane, in 1964. From 1966 to 1971, he served in the Kapuskasing area, and from 1971 to 1981, he was appointed to Timiskaming. Farmers appreciated the professionalism, the leadership and the talent of this great, passionate popularizer.
When the Alfred College opened in 1981, he was named assistant director and section head of the Department of Agriculture Management. He also taught the new farm management courses which required the professor to know everything about agriculture and animal feeding. As such, he taught accounting, agricultural mathematics, rural economy, farm business management, animal feeding, sales engineering and corporate tax to the students enrolled in the Food supervision program.
Demers also co-authored a socio-economic report about the financial management of Eastern Ontario farmers for the Ontario Ministry of Agriculture. A dedicated man who was caring of his students, many of whom were far away from home, he would always take the time to listen, encourage and help solve problems. A game changer, Demers established the Groupements de gestion agricole (farm management groups) and participated in the continuing education courses. He taught students and producers the importance of a sound financial, family and especially personnel management.
Actively involved in the community with many associations, including the UCFO, the Groupements de gestion agricole and the Alfred College, he also participated in social events like the Richelieu Clubs, the Couple and family movement and chorales.
He died prematurely at 48, at the peak of his career, but he passed on to the Franco-Ontarian community his sense of duty and his love for farming, an occupation that was more of a calling to him. A meeting room was named in his honour at Alfred College.