The relationship of circulating glucose, ketones, and F.F.A. to milk production in Awassi ewes

Abstract

The relationship between milk production, blood glucose, blood ketones and free fatty acids (F.F.A.) were studied in lactating Awassi ewes. Increased milk production in ewes was associated with diminished blood glucose and increased serum F.F.A. Clinical cases of ketosis were not observed.The ewes studied here could be divided into two metabolic populations depending on their blood ketone levels. Those with blood ketone levels of 11 mg % or more, did not show a significant increase in serum F.F.A. or a decrease in blood glucose values with increased milk production. The group of ewes with less than 11 mg % blood ketones showed a significant decrease in blood glucose and a significant increase in serum F.F.A. as milk production increased. Ketonemia of the high ketone group of ewes, was associated with relatively low serum F.F.A. levels. It is suggested that these ketones not originate from depot fat via serum F.F.A. These ketones and/or their precursors, acetic and butyric acids probably participate in caloric homeostasis and are associated with a glucose sparing serum F.F.A. suppressing mechanism.The suggestion that ketones derived from rumen (R.D.K.) should be distinguished from those derived from adipose tissue (A.D.K.) is discussed.