Complex sentence: At the time, the farm had over and 1,000 purebred Aberdeen Angus cattle (the largest Aberdeen Angus herd in the U.S.) Pew began eighteen Angus herds in Dutchess County, and was a director of the American Angus Association.
Split into simpler sentences: At the time, the farm had over and 1,000 purebred Aberdeen Angus cattle, which was the largest Aberdeen Angus herd in the US. Pew went on to start eighteen Angus herds in Dutchess County and serve as a director of the American Angus Association.