No Vermont farm would be complete without dairy cows, and in the early 20th century dairy quickly became Rokeby's most important agricultural product and eventually its only one. The Robinsons' dairy barn stood on this site for over 100 years, and though only its foundation remains today, it was once one of the farm's most impressive structures, with a middle section two-and-a-half stories tall and two smaller, older buildings on either side. Built with mortise and tenon construction and partly from recycled and random boards, perhaps to save on lumber costs, the barn was at one point painted red. Still visible are the outline of its stone foundation, the concrete pad of the milking parlor, and the cistern where water was stored outside the barn. After falling into disuse, it slowly deteriorated before being demolished in 1995. In the 1840s, Vermont's wool industry nearly collapsed after protective wool tariffs were repealed and the Erie Canal enabled competition from other states such as Michigan and Ohio. After 1870, the Robinsons shifted from sheep to dairy, and receipts from 1892 to 1894 show that they sold milk and butterfat locally to Allen Creamery and Ferrisburgh Creamery Co. in North Ferrisburgh, while butter made on the farm became well known and was sold as far away as Boston. Milk provided important but volatile income because prices fluctuated heavily and were lower in summer, perhaps because of high refrigeration costs and lower demand. Dairy production at Rokeby depended on most of the farm's buildings, with the dairy barn at the center as a three-part structure containing a milking parlor, two hay chutes from the hayloft, its own well and cistern, and a manger and holding pen, while hay and corn grown on Rokeby's acreage were stored in the Granary and hayloft and milk was cooled, separated, skimmed, churned, and stored in the Creamery.