The ISU McNay research herd consists of approximately 400 head of registered purebred Angus cows and is located at the ISU McNay Farm, Lucas County, Chariton, Iowa. The herd has been selected since 1996 for increased marbling and has been a valuable data resource for use in both short- and long-term research. Previous research with the herd has involved ultrasound technology to select for marbling, the inheritance of pinkeye resistance, genetic variation in response to vaccination, as well as the genetic basis of mineral and fatty acid concentrations in beef.