Metabolic Consequences of Increasing Milk Yield – Revisiting Lorna

Abstract

Nearly 50 years ago, a cow named Lorna achieved notoriety by producing nearly 50 kg of milk daily during measurements of her energy metabolism in a calorimeter at the United States Department of Agriculture (USDA) Energy Metabolism Laboratory at Beltsville, Maryland (Flatt, Moore, Hooven and Plowman, 1965; Flatt, Moe, Munson and Cooper, 1969). In the intervening period genetic selection in dairy cattle has produced huge increases in average milk yield, as well as changes in overall conformation, udder characteristics, and body size and structure (Hansen, 2000).