• Oakville
  • Oakville Dairy
• Oil Springs
  • Oil Springs Dairy
• Orangeville
  • Credit Valley Dairy
  • Gillespies Dairy
  • Kingshott Creamery Co.
  • Orangeville Dairy
• Orillia
  • Beers' Dairy
  • Model Dairy
  • Orillia Dairy Co.
  • Ringmore Farm Dairy
  • Silverbrook Ayrshire Dairy
• Orono
  • Cedar Dale Dairy
• Oshawa
  • Beaton's Dairy Products Ltd.
  • W.A. Gifford
  • Gimblett's Dairy
  • Ideal Dairy Ltd.
  • Lander's Dairy
  • Maple Leaf Dairy
  • Oshawa Dairy Ltd.
  • Riordan's Dairy
  • Staples Dairy
• Ottawa
  • Borden Co. Ltd.
  • Central Dairies Ltd.
  • City Dairy of Ottawa Ltd.
  • Clark Dairy Ltd.
  • Crescent Dairy
  • Dodd's Dairy
  • Echo Farm Dairy
  • W.J. Fenton
  • J.T. Frith
  • Highclere Dairy
  • R. Hopkins
  • Kemp's Dairy
  • Laiterie Leduc & Frere Dairy
  • Ottawa Dairy
  • H. Philion
  • Producers Dairy Ltd.
  • Pure Milk Dairy
  • B. Rothwell
  • Springwell Farms Dairy
  • Stinson's Dairy
  • Valley Co-operative Creameries Ltd.
• Otterville
  • Otter Dairy
• Owen Sound
  • Crystal Dairy Co.
  • Georgian Bay Dairy
  • Graham's Dairy
  • Maple Crest Dairy
  • Scenic City Dairy
  • P.D. Spencer's Dairy