In 1969 he moved to Cornell University, Ithaca, New York, where he studied Quantitative Genetics under Henderson and Van Vleck.
Since the mid-1970s, Schaeffer had aided livestock breeders in understanding new mathematical methods and solutions to apply within breeding evaluations.
By 1994 the ability to compare international breeding values was ensured through the Multiple Across Country Evaluation (MACE) Model.
Schaeffer's most recent work involved monitoring genetic evaluation systems for dairy and meat sheep.
He also worked on an Atlantic Salmon project with Dr. Elizabeth Boulding (University of Guelph) that used genomics to evaluate Canadian fish for disease resistance.