Regulation of fat mobilization in adipose tissue of dairy cows in the period around parturition.

Abstract

Samples of subcutaneous adipose tissue were taken from Dutch Black Pied and Meuse-Rhine-Yssel cows at regular intervals from about a month before until a month after parturition. Tissue was incubated in Krebs-Ringer bicarbonate buffer with 5% bovine serum albumin for 15 min and then for experimental incubations with fresh buffer without or with bovine insulin, glucose or norepinephrine. Rates of release of free fatty acids (FFA) and glycerol from tissue of cows in early lactation were greater than those from tissue of the same cows before parturition. The increase in fat mobilization after parturition was caused by an increase in rate of lipolysis and by an almost complete disappearance of the reesterification of fatty acids in the adipose tissue. FFA in blood also increased after parturition. During the period before and after parturition norepinephrine stimulated the release of FFA and glycerol from adipose tissue. Although glucose normally inhibits fat mobilization by stimulation of the reesterification of fatty acids, this effect was not seen during the first weeks after parturition. Insulin did not influence the effects of glucose on fat mobilization. (Abstract retrieved from CAB Abstracts by CABI’s permission)