Influence of dietary conjugated linoleic acid on growth, meat quality, lipogenesis, plasma leptin and physiological variables of lipid metabolism in rabbits.

We investigated the effects of conjugated linoleic acid (CLA) supplementation on growth, feed efficiency, carcass characteristics, meat quality, lipogenesis, and lipid metabolism in rabbits. One hundred forty-four New Zealand White rabbits, half males, half females, age 55 d, mean 1.8 kg BW, were randomly assigned to three weight- and sex-balanced feeding groups in which conventional pelleted diets were supplemented with 0, 0.25, or 0.5% of a CLA preparation. The CLA preparation contained 65% CLA isomers. Twelve rabbits (six males and six females from each group) were slaughtered at each of three slaughtering trials (2.5, 2.8, and 3.1 kg BW, or 76, 90, and 104 d of age). Conjugated linoleic acid supplementation did not influence growth performance (P > or = 0.05) or carcass characteristics but reduced perirenal fat at heavier slaughtering weights (P = 0.09 at 2.8 kg BW; P < 0.01 at 3.1 kg BW). Conjugated linoleic acid reduced acetyl-CoA-carboxylase (CBX) activity in liver (P < 0.05) and adipose tissues (P < 0.01) but did not influence malic enzyme (ME) or glucose-6-phosphate dehydrogenase activity. Significant differences were found between sex in interscapular fat (P < 0.05) for CBX, in perirenal (P < 0.01) and interscapular (P < 0.05) fat for ME, and a tendency (P = 0.070) in liver for glucose-6-phosphate dehydrogenase. The oxidative stability of longissimus lumborum muscle was increased at the higher level of supplementation (P < 0.05). Conjugated linoleic acid reduced (P < 0.05) triglycerides and total cholesterol in plasma with a trend to increased serum leptin (P = 0.06). Plasma triglycerides were higher in males than females (P < 0.01) and plasma leptin tended to be higher in females (2.57 vs. 2.13 ng/ml, P = 0.06). It is concluded that dietary CLA reduced carcass fat in rabbits slaughtered at 2.8 kg or above and altered lipid metabolism to produce lower concentrations of serum triglycerides and total cholesterol and higher concentrations of leptin.