In vivo measurement of lipogenesis in ruminants using [1- 14 C]acetate

Abstract

A method for the measurement of the rate of lipogenesis in ruminants using a continuous intravenous infusion of [1- 14 C]acetate and measuring the rate of [1- 14 C]acetate incorporation into adipose tissue lipid was evaluated. Subcutaneous adipose tissue samples obtained by biopsy over the course of a 6 h continuous intravenous infusion of [1- 14 C]acetate into a wether and a steer maintained in a ‘metabolic steady state’ demonstrated that the incorporation of [1- 14 C]acetate into subcutaneous adipose tissue lipid was linear for the duration of the infusion period. Subsequent measures of rates of [1- 14 C]acetate incorporation into adipose tissue lipid were made on adipose tissue samples taken at a single time point during the infusion period. The technique was used to measure rates of lipogenesis in the subcutaneous adipose tissue of fourteen Hereford × Friesian steers that had been fed a pelleted diet of dried grass at a range of metabolizable energy (ME) intakes from 1·1 × ME requirement for maintenance to ad libitum for 11 weeks. Rates of lipogenesis increased linearly (P<0·001) with increasing ME intake. It was concluded that the method is an effective technique for measuring rates of lipogenesis in specific adipose tissue depots in vivo in ruminants.