DIET-INDUCED VARIATION IN ACETATE METABOLISM OF OVINE PERIRENAL ADIPOSE-TISSUE IN-VITRO

Sixteen Blackface wether lambs (25-27 kg) were fed for 9 weeks on diet s based on either barley (B) or sugarbeet pulp (S), with either a low or high protein content. A constant amount of metabolizable energy (ME ) was given at twice maintenance level. At one stage the animals were fed frequently and blood was sampled over a 24 h period. Plasma was as sayed for acetate, glucose and insulin. After slaughter, the metabolis m of acetate to CO2 and lipid was investigated in perirenal adipocytes in vitro. Frequent feeding helped to achieve near-steady-state condit ions. Carbohydrate source influenced plasma acetate (P < 0.08) but not glucose or insulin. Level of protein in the diet influenced plasma ac etate, higher concentrations of acetate were associated with lower lev els of protein (P < 0.01). Acetate oxidation and incorporation into li pid was influenced by the concentrations of acetate, glucose and insul in in the incubation media (P < 0.001). Acetate oxidation was influenc ed by carbohydrate source (P < 0.05), whereas level of protein in the diet affected acetate incorporation into lipid (P < 0.05). These resul ts show how the balance of nutrients provided to a ruminant for metabo lism may influence selected plasma parameters and the metabolism of ac etate by adipose tissue, which may help to explain the reduced efficie ncy of ME utilization from more fibrous diets.