Mammary ketogenesis in the cow

¹ School of Veterinary Medicine and College of Agriculture, University of California, Davis, California

Acetate-2-C¹⁴ was injected intracisternally into one quarter of the udder of a normal and of a mildly ketotic cow. The standardized specific activities of fat and ketone bodies in the milk sampled from the injected quarter were greater than those from the noninjected quarter. The percentage of direct udder transfer of C¹⁴ was calculated for the normal and ketotic cow, respectively, as 92% and 83% for milk fat, 72% and 94% for beta-hydroxy-butyrate and 80% and 98% for the acetone plus acetoacetate fraction. Total-C¹⁴ recovery was decreased in the milk fat, but increased in the milk ketone bodies during ketosis. The results indicated that mammary ketogenesis from acetate occurs in cows and suggested that it is increased during bovine ketosis, probably in association with impaired mammary lipogenesis from acetate. The possible role of coenzymes in bovine ketosis is discussed.