Volume 88, Issue 6, December (2002), pp. 625-634 © The Author 2002
doi:10.1079/BJN2002726

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Effects of dietary fat and conjugated linoleic acid on plasma metabolite concentrations and metabolic responses to homeostatic signals in pigs

E. Ostrowska¹, R. F. Cross², M. Muralitharan³, D. E. Bauman⁴, F. R. Dunshea^1
1Agriculture Victoria, Victorian Institute of Animal Science, Werribee, Victoria 3030, Australia
²Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
³Deakin University, Geelong, Victoria, Australia
⁴Cornell University, Ithaca, NY 14853, USA

 (Received 19 November 2001–Revised 10 June 2002–Accepted 11 August 2002)

Sixteen female cross-bred (Large White × Landrace) pigs (initial weight 65 kg) with venous catheters were randomly allocated to four treatment groups in a 2×2 factorial design. The respective factors were dietary fat (25 or 100 g/kg) and dietary conjugated linoleic acid (CLA; 0 or 10 g CLA-55/kg). Pigs were fed every 3 h (close to ad libitum digestible energy intake) for 8 d and were bled frequently. Plasma glucose and non-esterified fatty acid (NEFA) responses to insulin and adrenaline challenges were determined on day 8. Plasma concentrations of NEFA were significantly increased (10·5 and 5·4 % for low- and high-fat diets respectively, P=0·015) throughout the experiment, suggesting that there was a possible increase in fat mobilisation. The increase in lipolysis, an indicator of ß-adrenergic stimulated lipolysis, was also evident in the NEFA response to adrenaline. However, the increase in plasma triacylglycerol (11·0 and 7·1 % for low- and high-fat diets respectively, P=0·008) indicated that CLA could have reduced fat accretion via decreased adipose tissue triacylglycerol synthesis from preformed fatty acids, possibly through reduced lipoprotein lipase activity. Plasma glucose, the primary substrate for de novo lipid synthesis, and plasma insulin levels were unaffected by dietary CLA suggesting that de novo lipid synthesis was largely unaffected (P=0·24 and P=0·30 respectively). In addition, the dietary CLA had no effect upon the ability of insulin to stimulate glucose removal.

Keywords:
Conjugated linoleic acids: Lipid metabolism: Pigs