The dairy industry in Iowa is undergoing a dramatic transformation, with many producers remodeling or building new facilities in order to expand their herd size. And during the past five years, many large herds—in excess of 1,000 cows—have been established in Iowa. Many of these operations focus on the milking cows and rely on others to provide replacement of heifers. Southern Iowa has an abundance of grass pastures that could provide an economical feed source for growing replacement dairy heifers. Objectives of this project were to measure performance and determine the economics of gain of pregnant dairy heifers when grass pasture in southern Iowa was the primary feed source.